Gear TiconaGearDesignPPT AM 1211 Gear-007R1

8/9/2019 Gear TiconaGearDesignPPT AM 1211 Gear-007R1

1/48

1 2011 Ticona Gears Webinar Gears-007r1 EN 12/11

Design andDevelopment of

Precision Plastic Gear

Transmissions

David Sheridan

Sr. Design Engineer

December 2011

2011 Ticona Gears Webinar Gears-007r1 EN 12/11


2/48


Section Outline

1. Why Ticona for plastic gears

2. Why plastic for gears

3. Design and engineering

4. Specifications

5. Prototypes and inspection

6. Testing and validation

7. Production


3/48


We Offer You a Broad Product Portfolio

Backed up by

A responsive service network

Skilled application

development and technicalsupport

Across the US, Europe andthe Asia-Pacific region

ImpetThermoplasticPolyester (PET)

VandarThermoplasticPolyester Alloy (PBT)

CelstranLong FiberReinforced

Thermoplastics (LFRT)

FortronPolyphenylene Sulfide(PPS)

VectraLiquid Crystal Polymer

(LCP)

Celcon /Hostaform

Acetal Copolymers(POM)

Global Service And Support

RiteflexThermoplastic PolyesterElastomer (TPC-ET)

CelanexThermoplasticPolyester (PBT)


4/48


Ticona and the Gear Industry

Ticonas been a leader in plastic gear

technology for over 40 years 1961: Celcon POM commercialized

Gears were among early applications

1969: First Plastic Gear Design manual

Among founding members of AGMAPlastic Gearing Committee

With UTS (TK Solver) co-developedPlastic Gear Design software basedon Ticona gear design manual

Developed PGEAR test machine

First plastic material supplier toexhibit at AGMA Gear Expo


5/48


Ticonas Gear Development Support

Our global technical centers supportcustomers through all stages ofapplication development

Gear analysis

Material selection

Gear material testing

Prototype tool design

Injection molding trials

Failure analysis Staff training from gear experts

Comprehensive gear material anddesign information


6/48


Section Outline




4. Specifications



7. Production


7/487 2011 Ticona Gears Webinar Gears-007r1 EN 12/11

Plastic vs. Metal Gears

Lower cost Injection molding vs. machining

Especially for large quantities

As-molded, no finishing

Greater design flexibility

Parts consolidation Molded-in features

Allow other gear geometries

Easy to mold, difficult tomachine, e.g., internal and

cluster gears

Less noiseLower modulus

Do not transmit sound

Greater tooth deflectionincreases load sharing andreduces transmission erroreffects

Light weight, low inertia

Reduce dynamic loadingand noise

Plastic Advantages



Plastic vs. Metal Gears

Inherent lubricity Do not need lubrication in

many low-load applications

Internal lubricants

For applications that

cannot use externallubricants

Computer printers

Motorized toys

Chemical and corrosionresistance External lubricants

Grease

Oil

Water Lawn sprinklers

Water meters

Shower heads

Plastic Advantages



Section Outline




4. Specifications



7. Production



The Plastic Gear Development Team

Molder

MaterialSupplier

Plastics Engineer

Quality ControlEngineer

ManufacturingEngineer

Gear Engineer

Project Engineer

Purchasing

ToolBuilder



Plastic Gear Development

Prime mover

Torque and speed

Inertia, natural freq.

Load(s)

Torque and speed

Special conditions

Inertia, natural freq.

Duty cycle

Life

Physical limits

Ratio

Precision

Efficiency

Lubrication

Environment

Temperature

Chemical exposure

Moisture exposure

Test requirements

Other

Identify ApplicationVoice of the Customer (VOC)

Define Operating Requirements

Anticipate Future Applications




Select Overall Transmission Geometry

From requirements

Minimum weight? Minimum size?

Good plastic designs may use moregears with split power path

Carefully consider added features Runout

Distortion

Shafting and bearings

Precision Efficiency

Housing considerations

Stiffness

Tolerances



Relative Gear Train Size

15:1 Reduction

Single Reduction100%

Double ReductionSingle Branch

40%

Double Reduction

Double Branch25%

2 Stage Planetary

9.5%



Preliminary Gear Sizing

Select materials

Select preliminary gear geometry

Number of teeth

Size (pitch or module)

Profile (tooth proportions) Nominal ambient conditions

Simple load analysis

K-factor

Unit load



Select Materials

Suit operating environment

Temperature range Dimensional behavior

Property behavior

Chemical environment

Dimensional behavior

Property behavior

Appropriate property mix Fatigue

Stiffness

Impact

Creep

Interaction with other components Friction

Wear


16/4816 2011 Ticona Gears Webinar Gears-007r1 EN 12/112011 Ticona Gears Webinar Gears-007r1 EN 12/11

Precision Engineering Components

Dimensional Requirements(i.e., Tolerances)

MUSTEqual Manufacturing

Capabilities



Concentricity Tolerances

for Unfilled Acetal

AGMA

12 DP

24 DP

12 DP24DP

Q7

Q10

1 2 3 4Gear Diameter (in.)

AGMA vs. SPI*

SPI Commercial Tolerances

SPI Fine Tolerances

12

10

8

6

4

2

0

Concentricity(10-3i

n.)

*The Society of the Plastics Industry


18/4818 2011 Ticona Gears Webinar Gears-007r1 EN 12/112011 Ticona Gears Webinar Gears-007r1 EN 12/11

Gear Engineers Job

To develop gear tooth geometry and assembly

specifications that will produce gears that functionsatisfactorily under all operating conditions andacross the entire range of manufacturing tolerancesand environmental influences on dimensions.




One Approach

Use analytical models for gear

tooth geometry and load analysis

Include all possible tolerances andenvironmental influences ondimensions in effective operating

center distance Design Perfect gear geometries

Develop gear geometry at tightmesh, maximum materialcondition

Re-analyze at open mesh,minimum material condition

Analyze worst load condition



Determine Production Tolerances

For All Components

Gears

Outer diameter and tolerance

Root diameter and tolerance

Tooth thickness and tolerance

Tooth tip radius and tolerance

Accuracy grade

Total compositetolerance (TCT)

Total Composite Error, TCE




Housing

Mounting center distance and tolerance




Shafts, bushings, bearings

Diameters and tolerance

Maximum and minimum radial play

Concentricity (TIR)

Maximum radial play Minimum radial play

Maximum bushing diameter Minimum shaft diameter

Minimum bushing diameter Maximum shaft diameter



Develop at Tight Mesh,

Maximum Material Condition

Maximum material condition Maximum tooth thickness Maximum outside diameter

Maximum root diameter

Minimum tooth tip radius

Select minimum effectiveoperating center distance

Optimize geometry Maximize contact ratio Minimize root clearance

Tip interference?

Minimize backlash

Minimize specific sliding

Load analysis at temperature Minimize or balance stresses

Excessive tooth deflection?

Tip relief?



Determine Effective Operating

Center Distance Range

Assembled center distance range Mounting center distance and

tolerance

Bushings, bearings, and shafts Maximum and minimum radial play

Runout (TIR) Gears

Total composite tolerances (Accuracygrades)

Environmental effects Environmental conditions

Temperature range

Humidity range

Chemical exposure?

Dimensional responsebetween housing and gears Thermal response (CLTE)

Moisture or chemical response

Examine when humid-hot

humid-cold

dry-hot

dry-cold

Determine extreme CD rangeand conditions



Analyze at Open Mesh,

Minimum Material Condition

Minimum material condition Minimum tooth thickness Minimum outside diameter

Minimum root diameter

Maximum tooth tip radius

Maximum effectiveoperating center distance

Check geometry Contact ratio > 1? If not, go back to beginning,

Select new diametral pitch ormodule

Change tooth proportions

Renegotiate tolerances

Load analysis attemperature Load capacity

Excessive tooth deflection?

Tip relief?


26/48


Analyze Other Load Conditions

Tight mesh condition is often

hot and humid Open mesh condition is often

cold and dry

But worst load condition

Open mesh - minimum loadsharing

Hot and humid - minimummaterial properties

Transient conditions

Cold housing and hot gears

Hot housing and cold gears


27/48


Finally

Iterate until all of the above works

Design time cheap

Changes during/after development costly ($ and )

Computer programs are necessary Analytical programs preferred

Graphical programs oftencause problems

Write specifications


28/48


Section Outline




4. Specifications



7. Production


29/48


Specifications

Plastic gear transmissions require significant engineering effort.

Components

Gears

Housings

Shafts

Bearings Variations

Manufacturing tolerances

Operating conditions(i.e., temperature, moisture)

Dimensions

Material properties

Making certain the resulting design intent is specified clearly,accurately, and precisely to the gear manufacturer is essential toensuring performance, cost, and delivery requirements are met.


30/48


Specifications


31/48


Specifications


32/48


Section Outline




4. Specifications



7. Production


33/48

33 2011 Ticona Gears Webinar Gears-007r1 EN 12/112011 Ticona Gears Webinar Gears-007r1 EN 12/11

High-Precision Gear Molding

Accurately predicting andconsistently controlling

(precision) shrinkage.


34/48


The Controlling Principle

Shrinkage is only affected by materials:

Orientation (polymer and reinforcement)

Temperature

Pressure

Almost everything can have an effect on at leastone of these three things and will effectshrinkage.


35/48


Prototypes

Verification of part and material performance

Verification of manufacturing capabilities with dimensionalcontrol

Represent production as mush as possible

Mold Mold material

# cavities, runners, gates, etc.

Cooling channels

Molder

Molding machine

Barrel size residence time

Injection rate

Clamp tonnage

Molding conditions Temperatures

Mold

Melt

Cycle profile Injection speed

Hold time & pressure

Cooling time

Screw RPM & backpressure

Identical to Production


36/48


Accuracy vs. PrecisionThe Target Analogy

High Accuracy

Low Precision

High Precision

Low Accuracy


37/48


Prototype Mold DevelopmentPrecision

Follow material suppliers molding recommendations

Establish appropriate processing window Maximize material properties

Resist correcting dimensions with extremeprocessing conditions

Wide, stable processing window Minimal variational effects on properties and dimensions

Maximize dimensional stability Consistent as-molded dimensions

Precision vs. cycle time

Minimize post-molding shrinkage Mold temperature must exceed operating temperature

Pay now, or pay later!

Design of experiments (DOE)

Stability Equals Precision


38/48


Prototype Mold DevelopmentAccuracy

Then correct tooling for shrinkage

Cut molds steel safe Undersized cavities

Oversized cores

Use inserts

Iterate

Measure thoroughly

Make what you designed

ThenCorrect for Accuracy


39/48


Plastic Gear Development Cycle

Design & Engineering

Prints & Specifications

Prototype Tool & Parts

Measurement & Inspection

Testing

Production


40/48


Inspection and Geometry Verification

During development

Elemental inspection (CNC) Profile error (involute error)

Lead error (helix angle error)

Pitch error (spacing error)

Runout (radial position error)

General inspection Outside radius

Root radius

Tooth thickness Measurement over pins or balls

Elemental Inspection for Development


41/48


Inspection and Geometry Verification

During production

Composite inspection (Double-flank roll checker) Total composite error (TCE)

Tooth-to-tooth error (TTE)

Runout

Stability Equals Precision


42/48


Section Outline




4. Specifications



7. Production


43/48


Testing and Validation

Geometry verification!

Realistic Properly represents end-use conditions Continuous testing when end-use is

intermittent Overheating No thermal or dimensional recovery

time

Temperature control Effective

Static loads Creep and creep rupture

Impact loads Motor stall load

Motor rotor inertia load Appropriate

Test procedures often developed formetal gears

Keep It Real


44/48


Plastic Gear Development Cycle

Design & Engineering

Prints & Specifications

Prototype Tool & Parts

Measurement & Inspection

Testing

Production


45/48


Section Outline




4. Specifications



7. Production


46/48


Production

Utilize prototype knowledge

Minimize deviations Mold

Mold machine

Molding conditions

Wide, stable process

Maximum material properties

Consistent dimensions

Correct tooling for accuracy

Measure thoroughly

Run capability study

Establish production QC methodology

Produce!


47/48

47 2011 Ticona Gears Webinar Gears-007r1 EN 12/11 2011 Ticona Gears Webinar Gears-007r1 EN 12/11

David Sheridan

Sr. Design [email protected]

Product Information800-833-4882

[email protected]

www.ticona.com
mailto:[email protected]:[email protected]://www.ticona.com/mailto:[email protected]:[email protected]://www.ticona.com/


48/48

Information is current as of December 2011 and is subject to change

without notice.

The information contained in this publication should not be construedas a promise or guarantee of specific properties of our products.

Any determination of the suitability of a particular material and part

design for any use contemplated by the user is the sole responsibility ofthe user. We strongly recommend that users seek and adhere to themanufacturers current instructions for handling each material they use.

Any existing intellectual property rights must be observed.

2011 Ticona. Except as otherwise noted, trademarks are owned by Ticona or its affiliates.

NOTICE TO USERS:

Gear TiconaGearDesignPPT AM 1211 Gear-007R1

Documents

Transcript of Gear TiconaGearDesignPPT AM 1211 Gear-007R1