Determining Gear Efficiency

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SITE SAFETY

TOOTH TIPS

COMPANY PROFILE:Butler Gear

Q&A: Bill Moore, SKF USA

MARCH 20

Determining Gear Efficiency

A New Tool forPrototype andProduction

The Art and Scienceof Broaching

ExxonMobil MaximizesGearbox Performance


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2 GEAR SOLUTIONS MARCH 2007 gearsolutionsonline.com


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Broaching is an extremely accurate and efficient process as

demonstrated with high volume production applications and is

unmatched by any other process. Nachi provides a wide

range of both machines and tools. Broach Tools are offered in

Conventional Gullet, Spiralglide, Spline, Blind Spline,

Full Form, Tension Draw Bar, Surface, Pot and Fir Tree styles.

We'll meet all your broaching needs!

Nachi represents the best in broach machine and tool technology.

Continued engineering design and developments showcase our

ability to meet industry needs. Think Nachi for broaching expertise,

reliable products and as your complete single source.


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gearsolutionsonline.com MARCH 2007 GEAR SOLUTIONS

MARCH 200

DEPARTMENTS

INDUSTRY RESOURCES

8

16

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52

industryNEWSNew products, trends and developments in the gear-manufacturing industry.

siteSAFETY TERRY MCDONALDSometimes its even more important to put safety rules in place regarding process

that you dont often per form than it is to address more familiar activities.

toothTIPSWILLIAM CROSHERThis installment addresses worm gear tooth forms, including descriptions of th

five standardized forms produced by milling or grinding operations.

Q&Awith BILL MOORE, Senior Vice President of Sales Development anChannel Management, SKF USA

companyPROFILEBUTLER GEARBY RUSS WILLCUTT

Everyone encounters obstacles, but the real challenge is in whether you cave in o

carry on. Read the story of a man who chose the lattertime and again.

DETERMINING GEAR EFFICIENCYBY RELLY VICTORIA PETRESCU, FLORIAN ION PETRESCU, AND NARCISA POPES

By analyzing certain parameters, the authors present an original method for deter-

mining the efficiency of gears.

THE ART AND SCIENCE OF BROACHINGBY CHRIS VAN DE MOTTERTo truly understand the benefits of broaching its important to take many things int

consideration, including the various methods, materials, and machines involved.

MAXIMIZING GEARBOX PERFORMANCEBY JEFF BIAMONTE AND TIM NADASDI, PH.D.

By choosing the proper lubricant, gearbox performance is improved. This article

describes ExxonMobils special formulation for gearbox applications.

CASE STUDY: A NEW TOOL FOR PROTOTYPE AND PRODUCTIOBY ROSS WEGRYN-JONES

This case study describes the development of an involute spline form milling tool f

prototype and production applications in standard CNC milling machines.

FEATURES

45 MACHINES 48 MARKETPLACE 51 ADVERTISER IN

p. 30

p. 36

18

20

30

36

40

VOLUME 5 NO.

p. 20

p. 40Cover Photography: Provided by ExxonMobil


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One of our editorial contributors sent us an e-mail the other day asking about

the best way to direct his customers to where his article is archived on our

Web site. We explained that he could go to the home page, click on current

issue, then archived articles or download past issues, and then scroll

to the year and issue in which the article hed written appeared. We also told

him that, rather than making his customer do the work, he could download

entire issues in PDF format going back to the first one we produced in 2003,

or individual articles since the June 2005 issue. That way he could send the PDF as

an e-mail attachment with a nice message to give it the personal touch. He was also

pleased to learn that he can utilize the search function included on our site to track

down articles for his own reading. Since this wasnt the first time weve had such a

request, it got me to thinking about what a wonderful resource you have in our online

archives. As Ive mentioned, every issue weve ever produced is found on our Web site,

and whats really great is that its accessible to anyone who visits, with no member-

ship form to fill out. Youll also find a great deal of additional information, including

press releases, our media kit, and categorized links to OEMs and other suppliers ofthe products and services you need. Again, theres a lot of great information there,

and we hope youll join the thousands of people who visit us each week by going to

[www.gearsolutionsonline.com].

In this issue of the magazine were pleased to present you with a fascinating mix

of articles, starting with one by Jeff Biamonte, global lubricants marketing advi-

sor, and Tim Nadasdi, Ph.D., product technical advisor for ExxonMobil Lubricants &

Specialties. They describe the development of the Mobilgear 600 XP Series of gear

oils, which was specially formulated for industrial gearboxes. Ross Wegryn-Jones, who

is national sales manager for Advent Tool and Manufacturing, Inc., has written a case

study on his companys development of an involute spline form milling tool for proto-

type and production applications in standard CNC milling machines. Three members

of the University Politehnica of Bucharests facultyRelly Victoria Petrescu, Narcisa

Popescu, and Florian Ion Petrescuhave joined forces to describe an original methodfor determining the efficiency of gears, and Chris Van De Motter, president of The

Ohio Broach & Machine Company, has penned a very informative article covering all

aspects of the broaching process.

Our columnists this month are Terry McDonald, who discusses the importance of

lubricating machines properlyamong other thingsin Site Safety, and Bill Crosher

considers the development of standards for worm gear tooth forms in Tooth Tips.

Butler Gear is this months company profile, and we think youll find the story of Hilton

Treudenas well as his sons, Tom and Leeto be both interesting and inspirational.

Bill Moore, who is senior vice president of sales development and channel manage-

ment for SKF USA, discusses the many benefits of developing a good relationship with

your local distributor in our Q&A department.

Id like to thank everyone whos submitted articles for consideration recently. We

do everything we can to publish those we feel will be of benefit to our readers, andwere always excited to welcome new writers and companies into our pages. If you

havent already, please send any article ideas you may have to the e-mail address

found below. All best:

Russ WillcuttManaging Editor

Gear [email protected]

(800) 366-2185


PUBLISHED BYMEDIA SOLUTIONS, INC

P. O. BOX 1210 PELHAM, AL 351241-800-366-2185

205-380-1580 FAX

P U B L I S H EDAVID C. COOPE

V I C E P R ES I D ENCHAD MORRISO

NAT I ONAL S A L ES M ANAGEBRAD WHISENAN

OP ER AT I ONS / C I R C ULAT I OTERESA HAL

AD M I N I S T R AT I V E AS S I S T ANMICHELE HAL

AR T D I R EC T OJEREMY ALLE

M A N A G I N G E D I T ORUSS WILLCUT

C ONT R I B UT I NG W R I T ERJEFF BIAMONTWILLIAM P. CROSHE

TERRY MCDONALTIM NADASDI, PH.D

FLORIAN ION PETRESCRELLY VICTORIA PETRESC

NARCISA POPESCCHRIS VAN DE MOTTEROSS WEGRYN-JONE

from themanagingEDITOR

PRODUCTION

EDITORIA

Gear Solutions (ISSN 1933 - 7493) is published monthly Media Solutions, Inc., 266D Yeager Parkway Pelham, AL. 3512Phone (205) 380-1573 Fax (205) 380-1580 International subscrtion rates: $72.00 per year. Periodicals postage pending at PelhaAL. Printed in the USA. POSTMASTER: Send address changto Gear Solutions magazine, P.O. Box 1210 Pelham AL. 3512Publications mail agreement No. 41395015 return undeliveracanadian addresses to P.O. Box 503 RPO West Beaver CreRichmond Hill, ON L4B4R6. Copyright 2006 by Media SolutioInc. All rights reserved. No part of this publication may be repduced or transmitted in any form or by any means, electronor mechanical, including photocopy, recording, or any informatistorage-and-retrieval system without permission in writing from tpublisher. The views expressed by those not on the staff on GeSolutions magazine, or who are not specifically employed by MedSolutions, Inc., are purely their own. All "Industry News" material heither been submitted by the subject company or pulled directly frotheir corporate web site, which is assumed to be cleared for relea

Comments and submissions are welcome, and can be submitted [email protected]

VOLUME 5 NO. 48


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Gleason Corporation NewsGleasons latest addition to its line of advanced, highly produc-

tive grinding machines is the 300TWG Threaded Wheel Grinding

Machine, designed to deliver the industrys fastest floor-to-

floor times for grinding of cylindrical gears up with a diameter

up to 300mm. The new 300TWG uses high-speed direct-drive

spindles and advanced Siemens CNC controls with Gleason

software to take full advantage of the latest multi-star t grinding

wheels. Multi-start grinding wheels are capable of improving

production rates up to five or 10 times that of conventional

single-start wheels. In addition, the 300TWG can be equipped

with a patented Gleason diamond-plated master dressing gear

system that can dress a multi-start grinding wheel in a very

short time, regardless of the number of starts, making it ideal

for higher volume production environments.

Users also have the option of applying a compact, fully auto-

matic CNC dressing unit located just above the grinding head

for conventional dressing with diamond plated dressing discs.

This is the optimal for the smaller batch requirements of job

shop or prototype production. The 300TWG is also offered with

an optional high-speed, fully automated two-station ring loader,

with easy integration of a spin-dry station if needed.

The 300TWG provides exceptional rigidity for a grindingmachine, derived from the use of the standard Gleason hob-

bing machine basea proven design that provides significantly

enhanced stiffness and stability as compared to other conven-

tional grinding platforms.

Gleason has also announced

that Gary J. Kimmet, vice

president worldwide sales

and marketing, has been

appointed president of the

Gear Research Institute (GRI).

The institute, affiliated with

the ASME and the AGMA, pro-

vides gear and related techno-

logical information and sup-

port by conducting research

and development, consult-

ing, analysis, and testing.

Since its inception in 1982, the GRI has conducted program

in important technology areas, including gear materials, he

treat, noise characteristics, durability, and many others. D

Suren Rao, managing director of the GRI and senior scient

of the Drivetrain Technology Centerboth located at Pe

State Universitysays, The Board of Trustees was pleas

to appoint Mr. Kimmet to this prestigious position, and to cotinue our relationship with a world leader in gear technology li

Gleason.

Kimmet joined Gleason Corporation in 1968 and has he

a number of positions with the company, including that

vice president of engineering. In his current position he

responsible for the marketing of Gleason Corporation produc

worldwide. He holds patents related to gear manufacturing a

processes and has published and presented technical pape

on gear technology. He received both his bachelors and ma

ters degrees in mechanical engineering from The Ohio Sta

University. He received the Lamme Award from Ohio State f

outstanding alumni contributions to the field of engineering

He is a past member of the Board of Directors of the AGM

and has been a member of the Board of Trustees of the Ge

Research Institute for nearly 10 years. Kimmet is also a memb

of the Board of Directors of the Gleason Foundation.

For more information go online to [www.gleason.com].

New Products, Trends and Developmen

in the Gear-Manufacturing Indust

TO SUBMIT:Companies wishing to submit materials for inclusion in Industry News should contact Managing Editor Russ Willcutt at [email protected]

Releases accompanied by color images will be given first consideration.


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Bison Gear AppointsNew PresidentBison Gear & Engineering Corp., a le

ing manufacturer of fractional horsepo

er gearmotors and electric motors, h

announced the appointment of Mar

Swarbrick as president and chief oper

ing officer. Most recently Swarbrick w

vice president and director of busine

excellence for Motorola. He led tpath to national recognition for perf

mance excellence when Motorola w

awarded the Malcolm Baldrige Natio

Quality Award in 2002 and the Balanc

Scorecard Hall of Fame award in 200

Martins track record as a leader

the disciplines of performance exc

lence, quality, customer advocacy, a

Six Sigma will drive Bison Gears contued growth by offering the best over

value package to customers, says R

Bullock, Bisons chairman and CEO.

Swarbricks 27 years as a busine

leader began in Ireland as a manufact

ing engineer for General Electric, whe

over a seven-year period he progress

to manufacturing manager. He spe

the next seven years with Verbat

(Kodak) as operations manager.

1991 he became operations director

Motorolas Land Mobile Products Sect

and shortly after became vice preside

and general manager with responsibi

for manufacturing operations and dis

bution for Europe, the Middle East, a

Africa.

Born in Cork, Ireland, Swarbrick w

educated at Trinity College, Dubl

and holds degrees in engineering a

mathematics. He studied manufact

ing and operations at IMD in Lausann


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Switzerland, and completed the Leadership Institute at

Northwestern Universitys Kellogg School of Management

in 2001.

With robust fractional horsepower gearmotor designs

offering up to twice as much torque in the same package

size as competitors, Bison Gear & Engineering Corp. con-

tinues to build upon a strong engineering tradition begun in

1960. Bison designs and produces gearmotors in parallel

shaft and right angle configurations, as well as AC and DC

motors only, for OEMs worldwide who demand the best long-lifetime value.

For more information contact Brenda Clemetson at (630)

443-5797 or [email protected]. Go online to

[www.bisongear.com].

New Tool PresettingSystems from BIG KaiserBIG Kaiser Precision Tooling, Inc., introduces the new STP-

35 Basic and STP-35 EzVision System. The system matches

the superior accuracy and T.I.R. of the STP-34, and has an

extended z-axis height to accommodate tools up to 20 inch-

es in length. The system has display resolution of .001mm

(.00004) for added precision.

The EzVision systems quick gage capability will measure

any tool. It manages and displays tooling and cutting edges

on the same monitor as the Speroni PC-based EzVision

control. The system features one-micron Heidenhein glass

scales. Its thermo-balanced and artificially aged pearlitic

cast iron structure ensures that the equipment is fully iso-

static and will not deform or distort over time or temperature

changea fundamental requirement in providing long-term

linear accuracy and repeatability.

Digital tool sensing removes the potential for error inher-

ent in manual measurement systems. They system does not

rely on the operators sight and judgment to focus and align

tools within its optics. It assures reproducibility of precision

settings, no matter which operator uses the instrument.

After inserting the tooling in the STP-35 EzVisions spindle,

the operator sets maximum diameter by reading simple digi-

tal values and following color codes on a personal comput-

er monitor. Obtaining

measurement values

is as easy as aligning

the tool within the field

of view or using oneof the custom mea-

surement macros. The

computer replaces the

digital readout used

on many other types

of presetters, so the

operator does not have

to learn to operate two sets of controlsboth digital readout

and computer monitor.

The EzVision control features a centering indicator box


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that is ideal for presetting angular cuts,

as in chamfering. It may also be used to

calculate nose radii and angles. Episcopy,

one of the STP -35s most popular options,

provides an easy way to detect defects or

deformities by illuminating and magnifying

the cutting edge.

As with all offline tool presetters, the

new STP-35 optimizes tool resources by

reducing tool set-up time and improving

machining production time, while also

enhancing the production of quality com-

ponents.

To learn more call (888) TOOL-PRO/866-

5776, send e -mail to bigkaiser@bigkaiser.

com, or go to [www.bigkaiser.com].

Paulo Adds SurfaceTreatment CapabilitiesPaulo Products Company announces t

addition of two surface treatments

its St. Louis, Missouri, facility. Paulo-

Louis now has the capability to perfo

gas nitriding. Gas nitriding is carried o

in a sealed retort with an ammonia atm

sphere at temperatures at or near 1,0

degrees Fahrenheit. Typical cycle tim

range from 24 hours to 72 hours. Pau

St. Louis can accommodate parts up

48 inches in length. In addition, Paulo-S

Louis has added the capability to perfo

a corrosion resistant ferritic nitrocarbu

ing process on carbon and alloy stee

This new process incorporates an oxid

ing stage that enhances corrosion res

tance as well as improving appearan

and overall performance. Paulo-St. Lou

continues to offer Nitro-Wear, a patent

ferritic nitrocarburizing process perform

in a fluid bed.

Paulo has operated a commercial he

treating facility in St. Louis since 194

Paulo-St. Louis is one of the largest a

most complete heat treating facilities

the region, offering continuous belt, batc

vacuum, induction heat treating, furna

brazing, cryogenics, and black oxidin

Paulo provides a wide variety of inno

tive engineered solutions in heat treatin

brazing, and metal finishing. Paulo aloffers its customers a broad range of m

allurgical services and extensive engine

ing resources.

For more information about Paulo co

tact Jim Heman, vice president of sal

and marketing, at (314) 450-4366.

online to [www.paulo.com].

Bodine AnnouncesImportant InternalPromotionsBodine Electric Company has announc

important changes to its leadership tea

The company has promoted Micha

Gschwind to vice president of sales a

marketing. Additionally, Edmund Glue

has been promoted to marketing a

product development manager, and Te

Auchstetter has been promoted to bu

ness development manager for custo

products.


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Gschwind, who has been with the company for nearly

30 years, has been instrumental in all aspects of product

research, development, and sales. He began his career at

Bodine as a sales engineer, directly serving accounts in

the Midwest and Western United States. In the mid-1980s

Gschwind transferred to Bodines Research and Development

group, where he developed electronic products for stepper

and brushless DC motors. In 1999 he became engineering

manager for Bodines AC, brushless DC, and e-TORQ product

lines. In 2002 he was named director of sales, where hemanaged the companys corporate sales force. Gschwind

holds multiple degrees, including a bachelors in electri-

cal engineering and a master of engineering management

degree from Northwestern University.

Mikes experience in produc t design, his extensive knowl-

edge of motor system applications, and strong understand-

ing of sales make him a welcome addition to our executive

team, says John Bodine, president and CEO.

Both Glueck and Auchstetter have extensive experience in

marketing and applications for the Bodine p roduct line. Since

joining the company in 1993, Glueck has been responsible

for market development and sales of all of Bodines AC and

Brushless DC products. In his new role he will oversee all

Bodine marketing activities. Auchstetter, who has been with

Bodine for 21 years and most recently has supervised all DC

and control products, will assume responsibility for manag-

ing opportunities for custom (built-to-order) products.

Im confident these changes will allow us to focus our

efforts in a consistent, customer-driven manner, Gschwind

says. The end result will be enhanced growth in markets

that demand the highly reliable, value-added products and

services offered by Bodine.

To learn more call (773) 478-3515, (800) 7-BODINE, orsend e-mail to info@bodine- electric.com. Go online to [www.

bodine-electric.com].

INDEX Offers Single-Spindle CNC BarMachineWith the new C65 CNC Single Spindle Bar Machine, INDEX

continues a 90-year tradition of successful single-spindle

bar automatics. The C65 can include a heavy-duty counter-

spindle and Y-axis for extended machining flexibility and

increased speed. According to Index, the new model offers

new levels of both productivity and flexibility for work done

from bar stock.

With optional 42mm (1 5/8inch), or 65mm (2 inch) bar

capacity, a maximum spindle speed of 6300, respectively

5000 RPM at 20KW or 26Hp at 100-percent (60min) duty rat-

ing and 105Nm (77ftlbs) torque, the C65 has enough power

to do a lot of work in a short time. Despite its large working

range, the machine exhibits a compact screw machine size

design, requiring little floor space so it fits into every shop

that runs screw machines.

Both turret slides and the counter-spindle slide offer a www.techinduction.com


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1g acceleration rate, and rapid traverse

rates of 25 and 50m/min (75 and 150 ft/

min), adding to the productivity because

of its faster motions. These production

advantages can often become essential

for the survival of a business, particu-

larly for job shops.

Speed: Three tools are in cut simul-

taneously almost all the time. And a

counter-spindle equipped with the usualZ-axis and X-axis allows the

user to complete parts very

quickly. Both axes are elec-

tronically coupled with the

second turret (slave- axes).

As a result, the third turret

can be working on the part

in the counter spindle while

the other two turrets work

on the main spindle, so that

three tools may be in cut

simultaneously.

Flexibility: Two Y-axes

for the turrets and a very

powerful counter spindle

provide flexibility unmatched by other

automatics for machining even complex

parts without compromising speed or

productivity.

An additional innovation is the polygon

generating capability, which results from

the counter-spindle operating as a poly-

gon generating attachment. The actual

polygon generating head is mounted

directly on the face of the chuck. No

additional equipment is required. T

very high rotational inertia and stiffne

of the counter spindle assures vibratio

free cuts, as well as long tool life, ev

on alloy steel.

An innovative highlight of the mach

is in the design of the guide-ways for t

turrets. The slides are not based on t

traditional linear system, but on a hig

innovative plate-type slide system. T


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slide surfaces are made of a match

between a cast iron plate, and steel

strips with ceramic-coated slides. This

slide system offers significant advantag-

es over the traditional slide ways: sev-

eral times greater stiffness, improved

dampening characteristics, and it is

more compact. The actual axis drive is

accomplished by rod-kinematic drive

linkages arranged on the rear of the castiron machine bed.

To learn more call (317) 770-6300,

send e-mail to [email protected], or

go to [www.index-usa.com].

Ball and Roller ScrewAssemblies from SKFSKF ball screws and roller screws are

available in a variety of cost-effective

types and designs to promote precise

positioning in linear-actuation applica-

tions for the automotive, aerospace,

injection molding, instrumentation, med-

ical, and machine tool industries, among

others. The extensive product line

includes rolled ball screw and ground

ball screw assemblies and planetary and

recirculating roller screws for especially

demanding applications.

Types of rolled ball screws include

miniature, universal and precision ver-

sions, and long lead ball screws. Ground

ball screws are offered both in preloaded

and non-preloaded designs. Uniquely

engineered TCM precision types fea-ture a robust and durable internal return

design. All assemblies can be equipped

with accessories for screw shafts and

nuts and can be supplied with the

necessary support-bearing package pre-

assembled and ready to go.

Planetary and recirculating roller

screws particularly suit applications

requiring accuracy, rapid acceleration,

fine leads, and high load capacities.

They can sustain static loads up to

1,000 tons and dynamic loads up to

200 tons. All roller screws are avail-

able in various styles and a full range

of diameters and leads to enable opti-

mum rotational speed and accelerati

capabilities. SKF ball screws and rol

screws can further be customized to s

isfy customer specifications.

For more information call Kyle

Fedorcha at (800) 541-3624 or 610-86

3709. Visit online at [www.linearmotio

skf.com].


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Ihope that you all had a very happy

Valentines Day and are looking for-

wardas I amto warmer weather.

Remember to ask your employees to

drive carefully this time of year. One of the

spotlights in this issue of Gear Solutionsis

lubrication. We have previously discussed

the importance of proper lubrication on

machines from a safety standpoint, but it

definitely bears repeating. The lack of prop-

er lubrication on a gear hobbing machine

can cause mechanical problems to the

machine, of course, but it can also create

a very hazardous situation for the operator

as well as other employees in the area. As

we all know, in the hobbing process both

the cutter and the hob are rotating as the

gear teeth are being cut. If, due to the

lack of proper lubrication, one or the other

spindles on the machine stop, not only

will the cutter and the part be damaged,but there is a very real chance for the cut-

ter, the part, or both to come flying out of

the machine, possibly creating a serious

injuryor even worse.

There are many other problems created

by improper lubrication, not the least of

which is the loss of production when the

machine must be put out of service for

repairs. We must maintain our machines,

which at the very least involves a program

of maintaining the proper lubrication in the

machine. Most machine manufacturers are

happy to provide a lubrication schedule,

and if the manufacturer is no longer in busi-

ness we are very fortunate in this country

to have a large network of used machinery

dealers and rebuilders that can furnish the

necessary information. I highly recommend

that you check your records to assure that

this information is readily available to your

employees. If you are having any problemsacquiring the correct information for your

equipment, please contact me and I will be

happy to try to assist you.

Another subject in the magazine this

month is broaching. For many of us in

the gear industry this is a process that is

only occasionally used in our facility, and

it is therefore a process that we are not

as familiar with as we should be. This is

a safety concern in itself. How many of

us address these processes that we only

occasionally use in our safety manuals? I

would be willing to bet that many of these

processes are often ignored, from a safety

standpoint. Each of these processes ha

their own safety concerns, and they mu

be addressed. Are the employees assign

to these jobs suitably trained? Are th

given the proper safety instructions prior

operating this equipment? Have all of t

necessary safety factors been taken in

consideration? I see many shops oper

ing broaching equipment that has been

use for many years and is not equipp

with the proper guarding, or even operat

controls. This is a very real safety haza

that must be addressed, particularly

the case of the shops that only use t

equipment occasionally. I urge you to ta

a close look at this equipment and corre

any safety hazards that exist.

In my last column we discussed t

safety issues involved with the use

hand tools. While thinking about writ

this installment last evening, I caught episode of Home Makeover on the tub

During this particular show one of the sta

was very seriously injured while operat

a hand grinder. It just points out that a

of us, even a well-trained professional, c

be seriously injured or even killed wh

doing something we often take for grante

We all need to take a step back and look

what we are doing. We need to make su

that we are not the cause of an accide

Its definitely better to take a little ex

time to perform a task safely rather th

losing the ability to ever do that particu

type of project again.

siteSAFETY terryMcDONALMember of the ANSI Subcommittee on Gear Safe

ITS DEFINITELY BETTER TO TAKE A

LITTLE EXTRA TIMETO PERFORM A

TASK SAFELYRATHER THAN LOSING

THE ABILITY TO EVER DO THAT PAR-

TICULAR TYPE OF PROJECT AGAIN.

With more than 30 years of experience in the gear industry, Terr y McDonald is partner and manager of Repair Parts, Inc., and a current membe

and past-chairman of the American National Standards Institute B11.11 Subcommittee on Safety Requirements for Construction, Care, and Use o

Gear Cutting Equipment. McDonald writes this monthly column specifically for Gear Solutionsmagazine, and he can be reached at (815) 968-449

or [email protected]. The companys Web site is [www.repair-parts-inc.com ].

Sometimes its even more important to put safety rules in place regarding equipment and processes that you

dont often perform than it is to address more familiar activities and tasks.

ABOUT THE AUTHOR:


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There is a wide choice in tooth forms,

each form with its own share of merits

and demerits depending on the applica-

tion. Several forms are associated with a

trade name. Under the optimum conditions for

any worm gear tooth profile, only line contact

is present when two gears of finite diameter

mesh and are rotated. Depending on the flex-

ing that takes place a contact area is only

produced under load and by a corresponding

elastic deformation of the tooth surfaces. The

rotating worm develops a series of rack profiles

advanced along its axis. The center sectionhas identical pressure angles on both sides,

but off-center the sections lose their symmetry.

The hob has an identical series of rack sections

generating the worms teeth. The conjugate

action being the same as that between a rack

and a pinion. It is the worms geometry that

decides the type of tooth form that is required.

Early on worm gear design fell into one

of three groups: non-throated, single-throated

(cylindrical), and double-throated (globoidal).

Non-throated worm gears only have point con-

tact. The teeth are not curved and do not envel-

op the worm. Any load will produce rapid wear,

and to all intents and purposes this group canbe ignored. ISO made the first attempt at cylin-

drical worm standardization in 1968, resulting

in five forms being standardized in ISO and

AGMAs 6022-C93. These five are designated

ZA, ZN, ZK produced with a milling cutter, and

ZK and ZI with a grinding operation. The thread

forms are closely related to the manufacturing

process:

Type of machining; e.g. turning, milling, and/

or grinding

The shape of the edges or surfaces of the

cutting tool

Position of the tool relative to an axial plane

of the worm

Where relevant, the diameters of disc type

tools or grinding wheels

Flank Form A: straight sided axial type ZA

The angle of generation and straight shape

producing line lie in one axial section. The line

of the cutter and the tooth flank generator of

the worm coincide, cutting the worm axis. The

thread flank is always a straight line in the axial

plane. A trapezoidal cutter has its edge lying

in the axial section and can cut both flanks

simultaneously. The form can be produced with

a straight sided lathe tool, milled, skived, or

ground. Another method is the inversion of the

process of cutting a helical gear with a rack cut-

ter. A grinding wheel or rotary milling cutter witha convex profile. In the transverse section the

profile is part of an Archimedian spiral. A trade

name associated with this form is Durand.

Flank Form N: straight sided in normal plane

of thread space helix type ZNThe straight

producing line and the angle of generation lie in

a plane inclined to the worm axis by the refer-

ence lead angle. Although, as with a ZA form,

the cutter form and tooth line coincide, they do

not in this form cut the worm axis. The cutter

is set at the level of the axis so that the cut-

ting face lies in the inclined plane of the lead

angle. The form can be produced with a coni-

cal milling cutter/grinding wheel or skiving. A

suitably profiled cutter allows the cutting edge

to progress tangentially from one end of the

face to the other. The profiles are approximate

because of effect due to change of helix with

change in thread height. These are sometim

produced in a lathe with a trapezoidal form t

with edges in the cutting plane that match t

profile of the thread space in a plane norma

the reference helix of the thread space.

Flank Form I: involute helicoid worm ty

ZIThe tooth form are sections of an invol

helicoids surface, which is tangential to

plane slanted to the axial section by the le

angle, and inclined to the worm axis by t

generating angle. This tangential plane a

the worm tooth flank meet in a straight li

which is the flank generator. This line lies intangential plane to the base cylinder.

Flank Form K: milled helicoids generat

by biconical grinding wheel or milling cutt

convex profiles in axial planesUnlike for

A, I, and N this form does not have straight l

geneatrices. The worm tooth flanks are tang

tial to a double cone, whose axis intersects t

worm axis at the selected lead angle. The co

lines are straight shape producing lines whi

with the normal to the worm axis, form the g

eration angle. The angle is located in the pla

of intersection which also contains the co

axis. It is cut and/or ground with a bi-coni

straight sided milling cutter or grinding wheThe tool axis is tilted to the lead angle of

thread at its mean diameter. The center pla

of the cutter intersects the worm axis at t

centerline of the space between the threads

Form ZC: concave axial profile formed

machining with a convex circular profile d

type cutter or grinding wheelUnlike for

ZA, ZI, and ZN they do not have straight l

geneatrices. They are generated with a rot

bi-convex disc type milling cutter or grind

wheel, similar to generating the AK form. F

tool dimensionsprofile radius, mean diam

ter, pressure angle, and thicknessdeterm

the form. The advantage of the AK form is th

adjustments can be made to accommod

for changes in tool diameter by modificatio

to the tool radius and angle. The propriet

name is Cavex.

toothTIPS williamCROSHEAuthor, engineer, and former director of tNational Conference on Power TransmissiThis installment addresses worm gear tooth forms, including descriptions of the five standardized forms

produced by milling or grinding operations.

ISO MADE THE FIRST ATTEMPT

AT STANDARDIZATION IN 1968,

RESULTING IN FIVE FORMS

BEING STANDARDIZED IN ISO

AND AGMAS 6022-C93.

ABOUT THE AUTHOR:

William P. Crosher is former director of the National Conference on Power Transmission, as well as former chairman of the AGMAs

Marketing Council and Enclosed Drive Committee. He was resident engineer-North America for Thyssen Gear Works, and later at Flender

Graffenstaden. He is author of the book Design and Application of the Worm Gear.


20/56

companyPROFILE


Hilton Treuden was not a man whoallowed a setback to get him down

for long. When one road ended, he

simply forged a new course of his

own. Strangely enough, the first obsta-

cle he encountered actually involved a

road.

Hed started a greenhouse operation

in Milwaukee straight out of high school,

selling plants and flowers, and within a

year he was doing so well that he bought

the building that he was leasing, says

Tom Treuden, recalling his father. Butthen the city leveled the structure when

it decided to build a new road, so he

was back to square one.

Rather than starting over again in a

new location, he decided to enter the

police academy, but after 11 years on

the force he grew tired of his future

being in someone elses hands, so herealized that it was time to exit that

road and find a new direction. He had

a friend who worked in a local gear

shop, and they decided to go into busi-

ness for themselves. Thats when Hilton

Treuden mortgaged his house, bought

his first gear machine, leased a nearby

garage, and Butler Gearnamed for

the Wisconsin city in which it is still

foundwas born.

Growing up, Tom Treuden spent plenty

of time around the shop, washing win-dows, sweeping floors, and cutting the

grass for 50 cents an hour. He joined

the company on a full-time basis after

graduating from high school in 1974,

running a lathe for about three years

before moving up to a gear cutter and

eventually learning to operate all of the

companys machines. I spent about 20years on the shop floor before I moved

into management in the mid nineties,

he says, so theres nothing here that

havent doneand that includes driving

the truck and cleaning out the toilets

Ive always thought that, no matter wha

your actual position is, youve got to

be willing to do whatever needs to be

done.

That included stepping into the role

of company president the day after his

father passed away in 2002. His brother, Lee, who is vice president, grew up

working at the shop as well, and after a

stint of military service he came on ful

time to oversee the companys produc

tion and maintenance activities.

Since its beginnings in a tiny rented

garage in 1960, Butler Gear has moved


21/56

Call (262) 781-3270, send e-mail to [email protected], or visit online at [www.butlergear.com].


FOR MORE INFORMATION:

By Russ Willcutt

EVERYONE ENCOUNTERS OBSTACLES, BUT THE REAL CHALLENGE IS IN WHETHER YOU CAVE IN OR

CARRY ON. THIS PROFILE TELLS THE STORY OF A MAN WHO CHOSE THE LATTERTIME AND AGAIN.

numerous times, most recently into a46,000 square-foot facility manned by

some 50 experienced employees. It

was originally 38,000 square feet, but

we soon added another 8,000 to that

so we could meet the growing demand

for our products, Tom says. Our cus-

tomers have really been good to us, and

theyve supported us, which is a great

incentive to do the best work you pos-

sibly can.

Its also great advertising. Not a

week goes by when we dont get a callfrom a new customer who says Ive

got a friend who buys from you, and he

told me that I should, too, he says,

And this guy might be from New York,

down in the Carolinas, in Florida, Texas,

or out on the West Coast. So we really

dont need a sales department since

the reputation weve worked hard tobuild over the years is working so well in

terms of attracting new business. There

are a lot of people out there who know

about Butler Gear.

Part of the reason for this is the

Treudens decision to separate the com-

pany from its competitors by offering a

maximum range of capabilities. Some

of that has to do with the equipment

weve purchased, Tom says. Anybody

can cut a five-inch gear, but not every-

body can produce 65- and 70-inchgears, like we can. But weve also made

a point of excelling at the more complex

gearing that nobody else wants to take

on. So I think that people have come to

know that, if theyve got a complicated

job that they need done, were some-

body they can trust to handle thatand

to do it right the first time.Asked if he inherited his fathers

green thumb, Tom Treuden laughs and

admits that I cant even keep a house

plant alive, but there is something

more important that he and his brothe

have allowed to thrivetheir fathers

legacy. And it brings me great joy to

know that, he says. I know that he

struggled, but he always managed to

provide for his family, and Ive learned

from his lessons as well as his mis

takes.People still call us all the time and

ask to speak to Hilton, and theyre so

sorry when I tell them that hes no lon

ger around, Tom says. But thats jus

proof of the kind of man he washe

touched a lot of people, and he couldn

be held down.

UTLERBUTLERGE RGEAR


22/56

GearEfficiency


ByRellyVictoriaPetrescu,FlorianIonPetrescu,andNarcisaPopescu

e

t

e rm

i

n

i

n g

Determini

ngByanalyzing

certainparameters,theauthorspresentan

originalmethodfordeterminingtheefficiencyofgears.


23/56


Abstract: This paper presents an original method for determining the efficiency of the gear. The originality

of this method relies on the eliminated friction modulus. In the following pages we analyze the influence

of a few parameters concerning gear efficiency. These parameters are: z1the number of teeth for the

primary wheel of gear; z2the number of teeth of the secondary wheel of gear;

the normal pressure angle on the

divided circle; and the inclination angle. With the relations presented in this paper, one can synthesize the gears

mechanisms. Today, gears are present everywhere in the mechanical world, especially the automotive, electronics, and

energy industries, etc. By optimizing this mechanism, one can improve the functionality of transmission gears.


24/56


IntroductionIn presenting this original method for calculating the efficiency of the ge

the originality consists in the way of determining the gears efficien

because we havent used the friction forces involved in couplingthis n

way eliminates the classical method, in fact. The necessity of determin

the friction coefficients by different experimental methods is eliminated,

well. The efficiency determinates by the new method are the same as in

classical method; namely, the mechanical efficiency of the gear. Precisone determines the dynamics efficiency, but at the transmissions gea

the dynamics efficiency is the same as the mechanical efficiency.

Determining the Momentary Dynamic (MechanicalEfficiencyThe calculating relations [2, 3], are the next (1-21), (see fig. 1):

with: Fm - the motive force (the driving force);

F - the transmitted force (the useful force);

F - the slide force (the lost force);

v1- the velocity of element 1, or the speed of wheel 1 (the driving whe

v2- the velocity of element 2, or the speed of wheel 2 (the driven wheel

v12

- the relative speed of the wheel 1 in relation with the wheel 2 (this

a sliding speed).

The consumed power (in this case the driving power):

FIGURE 1: THE FORCES OF THE GEAR


25/56


The useful power (the transmitted power from the profile 1 to the

profile 2) will be written:

The lost power will be written:

The momentary efficiency of couple will be calculated directly with

the next relation:

The momentary losing coefficient [1], will be written:

One can easily see that the sum of the momentary efficiency and themomentary losing coefficient Now one can determine the geometrical

elements of the gear. These elements will be used in determining the

couple efficiency,.

The Geometrical Elements of the GearOne determines the next geometrical elements of the external ge

[2,3], (for the right teeth,=0):

The radius of the basic circle of wheel 1 (of the driving wheel), (7)

The radius of the outside circle of wheel 1 (8):

One determines now the maximum pressure angle of the gear (9)

And now one determines the same parameters for the wheel 2, t

radius of basic circle (10) and the radius of the outside circle (1

for the wheel 2:

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Now one can determine the minimum pressure angle of the external gear (12, 13):

Now one can determine, for the external gear, the minimum (13) and the maximum (9) pre

sure angle for the right teeth. For the external gear with bended teeth ( 0) one uses t

relations (14, 15 and 16):

For the internal gear with bended teeth (0) one uses the relations (14 with 17, 18-A

with 19, 20-B):

A. When the driving wheel 1 has external teeth:

B. When the driving wheel 1 has internal teeth:

2cos

cos

cos

cos1

1

1

=

z

z t

m

The

RIGHT CHOICEfor

Machines,Servicesand

Toolingfor the

Gear Industry

Print and OnlineServices Available

gearsolutionsonline.com1.800.366.2185

Published by Media Solutions, Inc.

P.O. Box 1210

Pelham, AL 35124


27/56


Determining the EfficiencyThe efficiency of the gear will be calculated through the integration of momentary efficiency on all sections of gearing movement, nam

from the minimum pressure angle to the maximum pressure angle, the relation (21), [2, 3]:

5.0)(4

)2sin()2sin(]

2

)2sin()2sin([

2

1

])2sin(2

1[

2

1cos

11 2

+

=+

=

=+

=

=

=

mM

mMmM

a

i

M

m

M

m

M

m

dd

(21)

More precise (5) for determining momentary efficiency is the relation (22):

+

+

=

=

)2

(cos1

1cos

cos

1

11

1

21

2

1

2

tgzz

i

i(5)

(22)

ConclusionThe input parameters are: z1= the number of teeth for the driving wheel 1;z

2= the number of teeth for the driven wheel 2, or the ratio of transmission, i (i

12=-z

2/z

1);

0= the pressure angle normal on the divided circle;

= the bend angle.


28/56


29/56


30/56


The efficiency of the gear increases when the number of tee

for the driving wheel 1, z1, increases too, and when the pressu

angle, 0, diminishes. In addition, z

2or i

12are not much influen

on the efficiency value.

One can easily see that for the value 0=20, the efficiency tak

roughly the value 0.89 for any values of the others paramete

(this justifies the choice of this value,0=20, for the standa

pressure angle of reference). The better efficiency may be obtain

only for a020, the efficiency takes roughly the value0.89

any values of the other parameters (this justifies the choice of th

value,0=20, for the standard pressure angle of reference). T

better efficiency may be obtained only for a 020. But the pr

sure angle of reference, 0, can be decreased at the same time t

number of teeth for the driving wheel 1, z1, increases, to increa

the gears efficiency.

The module of the gear, m, has no influence on the gears e

ciency value. When 0is diminished one can take a higher norm

module for increasing the addendum of teeth, but the increase

the m at the same time with the increase of the z1can lead to

greater gauge. The gears efficiency, , is really a function of

and z1: =f(

0,z

1);

mand

Mare just the intermediate paramete

For good projection of the gear its necessary to have a z1and

greater than 30-60, but this condition may increase the gaugemechanism.

In this paper we have discussed how one determines the dyna

ics efficiency, but at the transmissions gears the dynamics e

ciency is the same as the mechanical efficiency. This is a grea

advantage of the transmissions gears. This advantage of t

gears mechanisms may be found at the cams mechanisms w

plate followers, as well.

Relly Victoria Petrescu is a lecturer and Narcisa Popescu is an

associate professor in the Department of Descriptive Geometry

and Engineering Graphics at the University Politehnica of

Bucharest. Florian Ion Petrescu is an assistant professor in the

universitys in Department of Mechanisms and Robots.

ABOUT THE AUTHORS:

1. Pelecudi, Chr., .a., Mecanisme. E.D.P., Bucureti, 1985.

2. Petrescu, V., Petrescu, I., Randamentul cuplei superioare de la angre-

najele cu roi dinate cu axe fixe, In: The Proceedings of 7th National

Symposium PRASIC, Braov, Romania, vol. I, pp. 333-338, 2002.

3. Petrescu, R., Petrescu, F., The gear synthesis with the best efficiency,

In: The Proceedings of ESFA03, Bucharest, Romania, vol. 2, pp. 63-70,

2003.

4. Petrescu, R., Petrescu, F., Gears design for the mechanisms highest

efficiency. In: The Proceedings of ICEGD05, Bucharest, Romania, vol. I

pp. 257-260, 2005.

5. Petrescu, R.V., Petrescu, F.I., Determining the dynamic efficiency of

gears. In: The Proceedings of SYROM05, Bucharest, Romania, vol. II,

pp. 381-386, 2005.

REFERENCES:


31/56


32/56

By Chris Van De Motter

The Art andScienceof Broaching



33/56

To truly understand the benefits of

broaching its important to take many

things into consideration, including

the various methods, materials, and

machines involved.



34/56


Broaching is one of the most productive and precise metal-c

ting operations performed today. Its also one of the mo

misunderstood.

Broaching resembles planing or shaping, in that the broach t

presents a sharp cutting edge to the workpiece and moves acro

it, removing a predetermined amount of material. What primarily d

tinguishes broaching from other metal-cutting operations is the to

ing used. A broach combines roughing, semi-finishing, and finish

teeth in a single line. Although many variations exist, the basic t

is an axial, multi-toothed rod, bar, or plate.

Broachings strengths are that it produces parts at a high ra

removes heavy amounts of stock, roughs and finishes in one pa

and permits the machining of complex contours and simple shap

alike.

Economical operation is another advantage of broaching. Wh

initial tool costs generally are higher than for other metal-cutt

operations, the cost per finished par t is lower because of the h

production rates broaching permits. Coupled with automatic

semiautomatic par ts-handling equipment, unskilled or semiskil

operators can be employed, fur ther reducing operating costs.

Broaches also make shallow cuts and perform finish ope

tions, often yielding smoother surfaces than can be attained w

other metal-removal processes. Some broaches have burnishsections that impart almost any finish desired, thereby elimin

ing the need for grinding. In terms of productivity, repeatabil

accuracy, and surface finish, broaching surpasses milling in a

one plane of a workpiece.

There are two basic types of broaches: surface (external), a

internal. Surface broaches cut on the outside of the workpie

while internal broaches enlarge or change the shape of an exi

ing hole.

Surface BroachesThe simplest surface broach is the slab broach, used for cutting

surfaces. Considered a general-purpose tool, it squares the enof parts or provides a reference surface for additional broach

or machining.

In applications involving hard surfaces or heavy stock remov

free egress (or nibbling) broaches are employed. They have se

of narrow roughing teeth positioned at a specific angle to t

centerline and quickly remove material. Full-width teeth follow t

roughing section and make semi-finishing and finishing cuts.

Slot broaches cut slots of various depths and widths. In ope

tions requiring high production rates, slot broaching is faster a

more economical than milling. Two or more slots can be cut sim

taneously with the proper tooling and fixtures. Its easy for stand

slotting broaches to cut slots in the ends or sides of a workpie

But thats not the case when cutting a slot along the par ts leng

Often, heavier stock removal rates are involved that demand ap

cation of a longer broach.

Contour broaches cut concave, convex, cam-shaped, contour

and irregular surfaces to extremely close tolerances. Broach

these surfaces requires that they be parallel and not prese

obstructions in the broachs path.

Manufacturers of turbine engines often use dovetail (or p

tree) broaches to create special forms in the compressor whe

that hold blades in turbine discs. This sort of broaching u

ally involves multiple passes, due to the heavy amount of sto

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35/56


removed and the complex forms involved.

Pot broaches cut precision external forms

such as involute spur gears, splines, slots,

and special tooth forms. Pot broaching

allows the task to be performed in a single

pass, making it an economical, high-produc-

tion process. It has replaced hobbing and

shaping in the manufacture of many types of

external gears. During pot broaching, parts

are pushed or pulled through the bore of the

pot-broach holder.

Straddle broaches incorporate two sepa-

rate slab-broach inserts to cut similar (or

identical) parallel surfaces on opposite

sides of the workpiece in one pass. Straddle

broachings advantage is that it maintains

a more precise dimensional relationship

between the two sides than would be pos-

sible with separate passes.

Internal BroachesThe round-hole broach is the simplest of theinternal broaches. It produces close-toler-

ance parts and smooth surface finishes in

high-production applications. The round-hole

broach has a series of teeth that fully encir-

cle the tool. Each tooth cuts on its entire

outer edge. When broaching ductile materi-

als, round-hole broaches that incorporate

chipbreakers are required. They effectively

break the stringy chips that form so they fall

off the broach, itself.

A variety of hole shapes can be broached

besides round ones. Internal broaches cut

square, rectangular, octagonal, and hex-

agonal holes, as well as any other internal

shape. All thats required is the proper

starting hole for inserting the tool.

One of the most common internal broach-

es is the keyway broach, which resembles a

slot broach. A fixture called a horn usually

supports the broach, locating the part in the

hole where the keyway is to be cut.

To cut internal gear forms, an internal

gear broach is used. Its tooth pattern gradu-

ally nibbles away at the workpieces inter-

nal surface, generating the desired gear

profile. A full-form finishing broach may be

needed to ensure accuracy and provide the

optimum surface finish.Broaching gun barrel bores necessitates

a rifling broach. This special tool is very long

so it can traverse the barrels full length. It

has relatively few teeth, as barrel grooves

are only a few thousandths of an inch

deep. The broach machine pulls the broa

through the bore while simultaneously rot

ing it to produce the spiral rifling patte

In some spline broaching applicatio

the pitch diameter must be precisely c

centric with the parts minor diameter

concentricity broach ensures this becau

it has a full-form finishing section posse

ing alternating round and spline teeth th

shave the minor diameter and spline form

Cutting splines in thin-walled parts

always a problem. During the operation t

walls expand with the broachs passage

then spring back, leaving improperly

splines. A cut-and-recut broach solves t

problem. It has a breathing area beh

the front cutting section that prevents p

shrinkage. The front of the tool cuts t

spline, than another cutting section at t

broachs end recuts it to precise to

ances.

Horizontal vs. Vertical MachinesThe two most important factors to consid

when selecting a broaching machine are t

type of broach required for the applicat

and the number of parts to be produce


36/56


Machine size is determined by broach

length, how much force will be exerted on

the tool, whether its a push- or pull-broach-

ing operation, and available floor space.

Horizontal machines are utilized primarily

for pull-through applications. One-way (cut-

ting in one direction) and two-way (cutting in

both directions) models are available.

The automotive industry makes extensive

use of large horizontal surface-broaching

machines to remove heavy amounts of

stock. These machines cut surfaces on

large parts such as cast engine blocks, cylin-

der heads, manifolds, and bearing clusters.

With carbide inserts, stock-removal rates of

1/4 or more are possible.

In the past most broaching was done on

horizontal machines, but today they represent

just 10 percent of all the broaching machines

purchased. Vertical broaching machines have

become more popular because they take

less space. This is an important cons

eration in plants where floor space is at

premium.

A drawback to vertical machines, thou

is that they require a higher ceiling than h

zontal models. In plants with low ceilings h

izontal machines are still used, and they a

find use as special, low-profile equipment

transfer lines and short-run applications.

Vertical machines typically are used for s

face broaching. In operation either the broa

tool passes over the workpiece, or it rema

stationary while the part moves.

Workpiece MaterialsAlmost any metal alloy is broachable, incl

ing soft materials such as brass, bronze, a

copper. Nonmetallic materialsgraphite, h

rubber, wood, composites, and certain pl

ticscan also be successfully broached.

Free-machining materials are easier broach than tough, hard ones. In stee

machinability is closely related to hardne

Steels with hardness of Rc 10 to 30

excellent candidates for broaching, with tho

in the Rc 16 to 24 range having the ide

hardness. Usually, steels harder than Rc

dull broach teeth too quickly, forcing frequ

tool changes and regrinds. Cast and m

leable irons allow more stock to be remov

per tooth than steels, as do brass and bron

Caution should be exercised when determ

ing stock removal rates. Too heavy a cut

cause the broach to overload.Broach hook angles vary between 0-degre

and 20-degrees+, depending on workpie

ductility. Brittle materials such as cast i

require a smaller hook angle, usually f

degrees to 10 degrees. The softer alloys

aluminum and rolled steel pose special pr

lems because they may adhere to the broa

teeth during cutting. This can be contro

with proper sharpening, the right cutting flu

adjustment of the cutting speed, and alter

the step per tooth and tool geometry.

ApplicationsEach broaching operation is different,

there are five areas in which broaching exce

on parallel, multiple surfaces; when fast c

ting is needed; automated operations; la

production runs; and tough materials. T

examples of typical broaching applicatio

that follow illustrate broachings versatility.

Figure 1 shows an outer gear form t

was pot broached. There are 31 teeth on t

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diameter and the depth of cut of .156. The

part is used in a transmission for locating

clutch plates.

Figure 2 shows another example of pot

broaching on various transmission parts.

Each part has been broached using a push-

up type broaching machine that loads the

part under the pot broach tools and pushes it

up through the pot. All of the splines or gear

teeth are cut at the same time around the

periphery. The part is completed in one pass

on the outside diameter form. Typically, this

operation will produce from 120 to 240 partsper hour.

Figure 3 shows the cam form for a couple ofouter race parts in the transmission or drive

mechanisms for an automotive manufacturer.

Again, these parts were pot broached so that

all the cam forms are completed in one opera-

tion. The difficulty in broaching these types of

forms is the inherent cutting force that tends

to turn the part as it is being broached. With

the proper design of the tools, this situation

is controlled and the proper form is broached

equally spaced around the part.

Figure 4 shows parts that have been inter-

nally broached to various gear forms. Both are

transmission parts used by the automotive

CONTINUED ON PG. 50 >

FIGURE 1

FIGURE 2

FIGURE 3


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Gearboxes are one of the most widely used types of industrial equipment in the

world. They are used as vital power transmission sources for nearly every kind

of business operating in the broader industrial market sector. Today, as industria

gearbox applications continue to become more advanced, manufacturers are

responding by producing an increasingly wide range of gearbox designs to meet their

customers evolving needs. Advancements in gearbox technology, especially enclosed

gearboxes, have allowed designers to decrease the overall size of a gearbox while main

taining the same amount of power transmission capability. These types of improvements

result in systems that place much higher demands on lubricants.

So, how can customers ensure they are purchasing a lubricant that will help maxi

mize the life of critical gearbox equipment? This article will describe important trends in

gearbox design and offer insightful tips that can help any plant manager, maintenance

professional, or purchasing agent make an informed decision in selecting the best gea

oil for the needs of their business.

Gearbox Design Changes: The Past 10 YearsIn recent years, gearbox technology has become significantly more advanced

Specifically, manufacturers have focused on developing systems that are more compact

more efficient, and deliver higher load capacities. These newer units offer significant

advantages in terms of delivering better performance, and their reduced size

ensures they occupy less space in a plant.

That said, it is important to note that, compared to previous modelsthese newer, high performance units typically require lubricants that offe

more comprehensive protection. Therefore, it is critical that companies

select a gear lubricant that can supply long-lasting protection for all gear

box components. What are some of the best ways to maximize gearbox

performance? Regardless of whether one has an older or newer gearbox

system, there are some key maintenance fundamentals that should be

followed.

First, it is strongly recommended that plant managers use a premium

quality oil. Secondly, plant managers should work closely with their gear

box OEM and/or their lubricant supplier to proactively develop a preventive

maintenance schedule. Specifically, it is important to carry out at least annua

visual inspections, and also to conduct a thorough oil analysis on the oil each

quarter for the most critical gearboxes in their production systems.

Common Signs of Inadequate Gearbox LubricationWithout inspection and oil analysis, noise, vibration, and oil leakage are often the first

signs of troubled gearbox operation. A common sign of inadequate gear lubrication that

is often overlookedbut is critically importantis micropitting.

Micropitting is surface fatigue that is mainly

observed in gears, but can also occur in rolling

element bearings. Micropitting causes destructive

wear that can occur within the first few hours o

operation. If left uncontrolled, micropitting can lead

to a reduction in gear tooth accuracy, and even gea

breakage.

Micropitting is not a new phenomenon. However

it is much more prominent with the increase in the

power density of gearboxes, and the subsequen

increased use of case hardened gears (carburized

nitride, induction and flame hardened). Although

a number of factors can affect the developmen

of micropitting, it is directly related to the surface

roughness and hardness of gears and bearings.

The surface roughness is usually due to asperities left from the finishing process

The generally accepted theory for micropitting is that, as two asperities from oppo-

ByJeffBiamonteandTimNadasdi,Ph.D.


By choosing the proper lubricant,

gearbox performance is improved.

Read on to learn about ExxonMobils

special formulation for gearbox

applications.


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site surfaces collide, they each deform elasti-

cally and/or plastically, leading to metal fatigue

beneath the asperity. Micropitting on gears may

not only lead to problems with gears, but to

bearings and seals as well. The main concern

with micropitting is that this wear, which is often

overlooked, can cause the shape of the gear

teeth to change.

Preventing MicropittingThe selection of the appropriate viscosity grade

is the first and most important step in choosing

a lubricant for any application. To find the right

viscosity, it is good practice to consult the OEM

manual as a starting point. However, many

OEM-suggested guidelines do not necessarily

consider factors that come into play if the gear-

box is operating under extreme conditions, such

as heavy loads and high temperatures. Ev

under extreme conditions, simply increasing

ISO viscosity grade of the oil is not necessa

preferred. Instead, selecting a lubricant wit

higher viscosity index, lower traction coefficie

or both should be considered. A higher visco

index can provide a thicker lubricant film un

operating conditions. A lower traction coeffici

can help to reduce surface fatigue.

Due to the high viscosity index and low tr

tion coefficient, moving to a synthetic gear

can help control micropitting. In addition

viscosity and traction, the additive chemistry

finished lubricants can have a dramatic eff

on micropitting performance.

For instance, it has been shown that cert

additives, especially conventional extreme pr

sure additives, can have a negative effect

micropitting performance. Choosing an oil t

is specifically designed to give micropitt

protection will not only reduce the risk of mic

pitting, but it will often deliver other benefincluding enhancing the durability and per

mance of a gearbox system and its most crit

components.

Mobilgear 600 XPIn November of 2006, ExxonMobil announc

the worldwide introduction of its Mobilgear 6

XP Series; a family of premium gear oils t

are formulated to deliver exceptional, long-la

ing protection for industrial gearboxes. With

advanced and balanced formulation, Mobilg

600 XP delivers exceptional performance othe long haul, exceeding the industrys m

demanding specifications, such as Flender

Table 7300 A, DIN 51517 Part 3 and AG

9005 E02. It is formulated to reduce wear a

enhance the performance of all critical gear

componentsincluding gears, bearings, a

seals. (Please see micropitting test on the

lowing page.)

By providing exceptional wear protection, t

new series of gear oils help control micropitt

and other forms of gear wear. Its balanced

mulation improves bearing and corrosion prot

tion, while remaining compatible with commo

used gearbox seal materials. Furthermore, i

designed to significantly reduce the formation

lubricant degradation byproducts that often le

to frequent oil changes.

Jeff Biamonte is global lubricants marketing ad

sor and Tim Nadasdi, Ph.D., is product technic

advisor for ExxonMobil Lubricants & Specialtie

To learn more go to [www.exxonmobil.com].

ABOUT THE AUTHORS:


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Gear Teeth After Micropitting Test:The boxed areas show micropitting formation. Test results

in Fig. 1 show that Mobilgear 600 XP provides superior

micropitting protection over generic oils.

FIGURE 1: 12 PERCENT

AVERAGE MICROPITTING

COVERAGE ON TEETH

(ROOT ONLY)

FIGURE 2: 49 PERCENTAVERAGE MICROPITTINGCOVERAGE ON TEETH(ROOT AND ADDENDUM)

FIGURE 3: CHOOSING THE PROPER LUBRICANT HELPS GEAR

TEETH RETAIN THEIR INTEGRITY

Typical Industrial Gear Oil not designedto protect agains micropitting

MOBILGEAR 600 XP


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By Ross Wegryn-Jones

CASE

STUDYCOMPANY:Advent Tool & Manufacturing, Inc.

CUSTOMER:MESCO


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The following case study describes the development of a

involute spline form milling tool for prototype and productio

applications in standard CNC milling machines.

WELLknown for its spe-

cialization in index-

able and solid car-

bide thread and form

milling tools, Advent Tool and Manufacturing

has developed an involute spline form milling

tool for prototype and production applications

for use in standard CNC milling machines.

Utilizing our patented insert locking and locat-

ing system on a standard shell threadmill-

ing platform, James Hartfordvice president

and general managerground a three-tooth

form in standard Advent Tool threadmilling

insert blanks to accurately duplicate the form

required on an end users spline shaft form.

The hurdle on this particular application was

twofold, Hartford says, getting the tooth geom-

etry planned out per the given workpiece diameter

and finding the right application and consumer to

prove out our prototypes.

As it was, Advent Tool distributor Muenz/

Engineered Sales Company (MESCO) had the right

application. Paul Dunn of MESCO had an end user

with an ANSI B92.1-1970 1-1/4 pitch diameter,

30-tooth spline form at 24/48 pitch and 2-3/4

in length. This end user needed to generate an

extremely accurate spline form on their stainless

steel shaft with a very fine surface finish require-

A New Tool for Prototype and Production


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ment. With the workpiece requirement being of stainless steel, the

customers options to generate this form were limited, to say the least.

Finding the right manufacturer who could par tner with us and our cus-

tomer on this engineered application was the key, Dunn says. Advent

Tool was the right kind of company with the right kind of tool designs,

and they were willing to put their expertise to work.

Advent Tool has had

vast experience in thread

and form milling a vari-

ety of forms in stainless

steels. We knew that our

standard form milling

platform was more than

adequate for the proj-

ect at hand. With some

development time we

completed the inserts,

and success was achieved immediately with the end user in terms of

cycle time and tool life; not to mention a relatively minimal investment

in specialized spline hobbing equipment and tooling.

A typical theme of spline milling applications that we are seeing

lately is the need to reduce cycle time and complexity. An application

for spline milling was recently quoted and a tool build is in progressfor a Tier I automotive supplier that typically took the shaft offline to

be hobbed on traditional high speed steel spline hobbing equipment

and then brought back to the original CNC milling machine for the final

operation. Using the Advent indexable spline milling tool to generate

the spline form, and foregoing the offline process, the manufactu

was able to reduce cycle time significantly. Not measured, but certa

implied, were quality and time saving gains by not having to find

part again using the aforementioned offline process.

The Advent indexable tool design utilizes completely ground t

bodies and locating devices to hold carbide inserts in an exact po

tion axially and radially. This unique, patented t

design minimizes uneven chip loads amongst

inserts while cutting the workpiece. This precisi

in turn, leads to longer tool life, faster speeds a

feeds, and more accurate form generation in

workpiece. Coolant through is standard with Adv

Tools, with coolant directed between the flutes

right at the cutting tool interface. As you can im

ine in an aerospace part, the thread forms must

perfect. Advents tool design is known for accura

repeatable thread generation in the aerospa

commercial, and automotive industries. This spline form applicat

represents the cutting edge of Advents form milling pursuits to dat

The application listed here has utilized standard Advent threadm

ing bodies, with specialized inserts. Advent Tool has recently had ca

for some coarser pitches and larger pitch diameters with finer pitch

In these cases, standard milling bodies were not used, but the saconcepts with a special body applied. H13 tool steel was used, a

like their coarse pitch thread milling cousins, bodies were modified a

made to suit taller inser ts with greater minor/major diameters.

Initial internal tests conducted by Advent to provide proof-of-conc

Headquarters:Add: 10, Lixin Road, Dongli Economy Development Zone TIANJIN P.R. CHINATel: 0086-22-24981172 Fax: 0086-22-24981170Web: http://tj-jcmt.com Email: [email protected] code: 300300

Maximum module up to 30mm (D.P. 0.85) spiral bevel gear,

zero bevel gear and hypoid gear by generating method.

JINGCHENG suggests YH6012 NC spiral bevel gear generator series

n Products range:Spiral bevel gear generator series (D.P. 10-0.85, diameter:5-63)Gear pointing machine series (diameter:1.2-15.7)Spiral bevel gear lapping machine series (diameter:19.7)

Auxiliary machine seriesNC gear cutter sharpenerManual gear testerNC spiral bevel gear tester

All products have one year warranty. As part of our commitment to providingexcellent customer service, we guarantee to contact you within 24 hours after aproblem is brought to our attention. We welcome your business around the world.

TIANJIN JINGCHENG MACHINE TOOL MFG Co., Ltd.

USA Representative office:Tel: 001-714-972-8364 Cell: 001-714-244-8808Email: [email protected] or [email protected]: HAROLD LIU

Germany Agency:Contact Person: Lanny ChenAddress: TopBox C2207, No. 69 West Beichen RoadChaoyang District, Beijing 100029, ChinaTelephone: 0086-10-58772450Email: [email protected]: http://www.eisenbeiss.comFax: 0086-10-58772480

Brazil Agency:Contact Person: Fernando B. Gandara MendesWebsite: www.ghc-equipamentos.com.brTelephone/Fax: 55114702-4433Email: [email protected]: 55119938-6131

Finding the right manufacturer toFinding the right manufacturer to

partner with us and our customer waspartner with us and our customer wasthe key and Advent Tool was the rightthe key, and Advent Tool was the right

company with the right tool designs.company with the right tool designs.


45/56


ABOUT THE AUTHOR:

Ross Wegryn-Jones is national sales manager for Advent Tool and Manufacturing, Inc.

He can be reached at (800) 847-3234, (847) 549-9737, or [email protected]. Go online to [ www.advent-threadmill.com].

in house were performed on H13 tool steel, and the subsequent

results were impressive. In a standard CAT 40 class vertical machining

center with a fourth-axis rotary table, two passes were needed in each

three tooth cutting pass with this eight-flute shell mill tool. The process

took a total of 20 passes to complete the part, and 880 surface feet

per minute, 1600 rotations per minute, 40 inches per minute feed, and

.003 chipload per tooth were the parameters for the roughing pass.

1700SFPM, 3000RPM, 30IPM, and .0015 chipload per tooth were

achieved for the finishing pass.

Naturally, this is not going to be competitive with spline rolling in

terms of cycle time. However, as it is with most things in life, each

choice has its own limitations. Advent tools care not about spline

length. Likewise, the form and the surface finish can be more tightly

controlled using the Advent system. As long as there are no shoulder

interferences (there are options available if this is the case), the mill-

ing tools are made to mill workpieces, regardless of workpiece length.

Coarse or fine pitches do not matter as much with the Advent system;

the inserts are built to suit, and bodies can be made to suit if needed.

For that matter, assuming a standard tool body, lead times for new

spline milling tools are relatively shortabout four weeks from print

approval. While other processes have their ins and outs, the typical

Advent consumer already knows the parameters of milling.

Threads are just defined forms, as specified by ANSI and ISO, a

the appropriate tools are made and kept on the shelf, in stock,

Advents headquarters. Coatings are applied to suit the applicati

but are typically stocked in either uncoated, TiN, or TiAlN varieti

Serrations on (previously) broached parts, front and back chamfers

ring/snap ring grooves, and even inser ts to generate a defined sur fa

finish on mating pipe flange parts have been successful applicatio

Advent Tool has also successfully designed and built complete bl

print specials for other forms that customers need as well, suc

Determining Gear Efficiency

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Transcript of Determining Gear Efficiency