MECH 311 MANUFACTURING PROCESSES LAB...

MECH 311

MANUFACTURING PROCESSES

LAB MANUAL

CONCORDIA UNIVERSITY

SUMMER 2011

COURSE INSTRUCTORS:

DR. JOHN CHEUNG

LAB INSTRUCTORS:

DANIEL ELIZOV

MICHAEL REMBACZ

WRITTEN BY: R.KUNANEC, D.MORGAN, D.ELIZOV

MECH 311 LAB CHECKLIST

(Students MUST comply with all items listed below before entering each lab session. Students must supply their own glasses / shoes / clothing for this lab.)

Safety glasses

Closed toe shoes (No sandals, flip-flops, etc.)

Old clothes / Lab coat / Coveralls (you will get dirty!)

No loose clothing

No dangling jewellery / rings

No cell phones

Tie back long hair

Completed material from previous classes (if applicable)

No food or drink allowed in the lab

1

Lab Outline & Requirements

Arrive on time as late people will not be admitted to the lab.

Before Lab 1 – Before entering the EDML, the student must have successfully passed the

EDML mandatory safety quiz. A successful pass is considered a mark of no less than 100%.

Should the student fail on the first attempt, they will have two other chances to complete the

test; however there is a time delay of 30 minutes between tries. Failure to have successfully

completed the quiz before entering the student’s first scheduled lab will result in a deduction

of 10% from the final lab mark. See the lab instructor if you fail the test 3 times. Please print

out pages 10, 13 & 27- 29 of this manual and bring it to lab #1.

Lab 1 – The student will learn different metrology operations and techniques. The student will

be required to measure an existing gyroscope in the lab and note all of the dimensions on a

sheet which the student must print from the lab manual. Once the measurements have been

taken, the instructor will give a brief introduction to all the machines in the EDML followed by

an introduction to use the mill and lathe for a basic material removal operation. Before leaving

Lab 1, have your sheets initialed by either the lab instructor or TA. With the duly completed

sheets from the lab manual, the student will be required to create three detailed CAD

drawings for their next lab session, as well as submitting the initialed data sheets. The use of

2D AutoCAD is prohibited. Suggested platforms are Solidworks and Catia.

Lab 2 – The student will be required to hand in the completed detailed drawings and data

sheets at the beginning of their lab session. These drawings will be corrected and returned.

No marks will be given for the drawings, however failure to hand them in, or a drawing that

has little or no effort put in to it will result in a deduction of 10% from the final lab mark. The

students will be required to correct their mistakes and resubmit their drawings in the final

report.

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The student will also witness a demonstration of either a gyroscope frame or gyroscope rotor

being fabricated. The students will be required to note all the steps in a process sheet

template which can be found at the end of this manual or on the EDML Moodle site. Care

must be taken when filling out this sheet as students will have to follow it to fabricate their

own part. After the demonstration, the student will be placed on his or her own machine and

will complete either half of the frame or the entire rotor. Please print out and bring at least 2

copies of the process sheet template.

Lab 3 – The student will continue to complete all the machining operations on the part they

started in Lab 2. The students on the milling machine will continue machining their frame,

while the students that are on the lathe will be able to machine the shaft and fabricate the ring

for the gyroscope. Students must be sure to receive their corrected detailed drawings.

Lab 4 – The student will witness a demonstration of either a gyroscope frame or gyroscope

rotor being fabricated (whichever they did not witness in Lab 2). The students will be required

to note all the steps in a process sheet template which can be found at the end of this manual

or on the EDML Moodle site. Again care must be taken when witnessing the demonstration

and filling out the process sheet as students will be required to machine the part individually

on their own machine. Please print out and bring at least 2 copies of the process sheet

template.

Lab 5 – The student will continue to complete all the machining operations on the parts they

started in Lab 4. The students on the milling machine will continue machining their frame,

while the students that are on the lathe will be able to machine the shaft and fabricate the ring

for the gyroscope.

Before Lab 6 – After all machining steps are completed, the student will proceed to fill out an

inspection report for the frame, rotor, shaft and ring. A template can be found at the end of

this manual or on the EDML Moodle site. The student must complete this on their own time

and before lab 6. The EDML will be open every weekday from 9am till 5pm (Closed from

noon till 1pm). 2 calipers are available in H0024-1, if the student requires measuring

equipment.

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Lab 6 – The student will be able to engrave writing on their gyroscope by using the CNC

milling machine in the EDML A. Students will next be able to polish their gyroscope frame. At

last, students will also be able to fabricate a stand for the gyroscope using a GMAW welding

process. Once the welding / engraving / polishing procedures are completed, the student will

be able to proceed with assembly followed by testing.

After Lab 6 – A final report will be required. The deadline will be determined by the

manufacturing instructor. Please see the following pages for the report content.

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Final Report:

The report must be formatted as follows:

1.0 ENCS Lab Expectation of Originality Form

2.0 Title Page (name, section, date, ID#)

3.0 Table of Contents

4.0 Introduction

4.1 Brief introduction to the project and machines used and the parts being fabricated

5.0 Frame

5.1 Detailed Drawing (Proper drawing, landscape format, title block, CAD only)

5.2 Process plan

5.3 Inspection report

5.4 Conclusion (Comment on how well (or not) your frame turned out)

6.0 Rotor


6.2 Process plan


6.4 Conclusion (Comment on how well (or not) your rotor turned out)

7.0 Shaft


7.2 Process plan


7.4 Conclusion (Comment on how well (or not) your shaft turned out)

8.0 Ring

8.1 Process plan


8.3 Conclusion (Comment on how well (or not) your ring turned out)

9.0 Assembly Drawing + Assembly Procedure + Bill of Materials

9.1 Assembly drawing is a view of the gyroscope with all the components shown as they

go together. (ie. fully assembled) Each component should be labeled with a number

which corresponds to the same number on the bill of materials. Assembly drawings

typically only have the overall dimensions of the assembly and do not have all the

dimensions from the working drawings. See pages 71 and 72 (not the Acrobat page

numbers, the ones that appear on the bottom right of the page) in the lab manual for

an example. Although dimensions are not always required on assembly drawings.

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9.2 Assembly Procedure is a detailed step by step guide for workers on how to assemble

the product. Imagine you are writing these steps for someone that has never seen

this type of gyroscope.

9.3 Bill of Materials (BOM) is a list of all components required to assemble the final

product. Include: quantity, was part purchased or fabricated, drawing number of

fabricated parts, description of parts, etc. The BOM can be included on the assembly

drawing if it fits.

10.0 Overall conclusion

10.1 How did your gyroscope turn out? Any problems?

10.2 Any comments on how the lab should be improved for next year

Marking:

Final report 70

Format + Content 10

Drawings (3) 27

Process sheets (4) 34

Inspection sheets (4) 14

Assembly Drawing 8

Assembly Procedure 2

BOM 5

Manufacturing Evaluation 30

Final lab Mark (10% of Grade) 100

Bonus Question: 5

Empirically determine if your rotor and frame are balanced (static only) based on your dimensions. Show how the mass of the frame can provide a balanced motion, and if not, what percent error exists.

Deductions:

As noted above in the lab outline, deductions of up to 30% of the final lab mark may be applied for incomplete or not submitted items or missed labs. In addition, a deduction of 15% may be applied for students that fail to abide by the EDML safety rules or show insubordination toward the instructor, technician, POD or any other authority figure in the EDML. Failure to properly clean one’s machine at the end of the lab period will result a 5% penalty per infraction. Lastly, a final report submitted after the date set by the Manufacturing Instructor will result in a 2% per day deduction.

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LAB 1 – METROLOGY AND THE EDML

1. Introduction to EDML

The Concordia Engineering Design and Manufacturing Laboratory (EDML), located in H-0024, is a valuable resource of the Mechanical and Industrial Engineering Department. The EDML provides support to the entire Faculty of Engineering and Computer Science for all the staff and students’ needs. The EDML staff is able to provide helpful suggestions and ideas for designs, from their varied and extensive experience.

The student side of the EDML, located in H-0026, is open to students from within the faculty, working on course related design projects, as well as extra-curricular projects, such as Concordia’s student built Formula SAE race car (Figure 1).

FIGURE 1. PHOTO COURTESY OF CONCORDIA’S SOCIETY OF AUTOMOTIVE ENGINEERS (CONCORDIA SAE)

It is important to understand the manufacturing processes involved in the design and fabrication of a part because an improperly designed part results in increased costs, wasted material and wasted time. By understanding these processes, the engineer can make choices in his or her design to reduce costs, reduce waste, and facilitate the fabrication of a part.

For example, an engineer is tasked with designing a sealed box. The engineer decides to make it out of steel, and to weld it from the inside. He or she takes it to the machine shop, where the designs are rejected because it is impossible to weld inside a sealed box. Had the engineer understood the process of welding, he or she would have been able to avoid this costly mistake, in terms of downtime and resources.

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1.1. SAFETY REGULATIONS

The use of the EDML, while open to all students, is regulated by a set of strict safety rules and procedures, to be obeyed at all times. Compliance with the regulations are mandatory; those in contravention of the rules will be given a warning. A subsequent infraction will result in the immediate expulsion of that person from the EDML, and further access can be denied.

A summary of the safety rules found within CON-EDML-004 are found below. For the complete EDML policy, please visit http://users.encs.concordia.ca/~dng

Personal

• Always wear safety glasses

• Wear appropriate footwear and clothing

o No loose clothing

o Roll up sleeves

o Take off ties, scarves, etc.

o No open toe shoes

• Wear hearing protection (if required)

• Remove wristwatches, rings, bracelets, etc.

• Never wear gloves when operating machines

• Long hair must be tied up

• Report all accidents or injuries immediately

Safe Work Practices

• Understand how the machine works and how to stop it quickly before operating it

• Be sure all guards and safety devices are in place and in working order

• Keep hands away from moving parts

• Stop machine before measuring, cleaning or making adjustments

• Only one person operates a machine at one time

o Do not talk to or distract a person while they are operating a machine

• Keep work area clean and tidy

• Chips, oils, heat, and sharp tools are hazards

• Be alert, be aware

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Safety at the Machine

• Be sure cutting tools and work piece are properly mounted

• Remove all burrs and sharp edges from work piece

• Be sure work is clamped securely

• Before starting a machine, ensure cutting tool and machine parts clear work piece and clamping

• Use proper tools for the job

• Wear any safety equipment specific to equipment being used

• Be careful when lifting heavy objects

Be familiar with the posted Concordia Standard Lab Safety Rules. There must be a qualified technical staff member present when you work in the EDML.

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2. INTRODUCTION TO METROLOGY

Metrology is a very important part of the design and manufacturing process. Unless numerical values are specified and measured, one cannot ensure proper fitting between parts. This is very impractical and inefficient; in reality no part can be made without some form of measurement. In the next section of this lab, you will be introduced to a scale of measurement used throughout machine shops around the world.

Note: While measuring instruments are available in both Imperial and SI units, we will be using Imperial measurements for this course.

2.1. INTRODUCTION TO VERNIER SCALE

Pierre Vernier (1580-1637) in 1631 invented the linear scale. This scale is one of the simplest to use for measurement, and offers a fine discrimination. The Vernier scale is used in all modern measuring devices. Two instruments we will be covering are the Vernier caliper and Micrometer, both of which use a form of the Vernier scale.

2.1.1. INTRODUCTION TO VERNIER CALIPER

FIGURE 2. VERNIER CALIPER (PICTURE COURTESY OF TECHNOLOGYSTUDENT.COM)

The modern Vernier caliper, as shown in Figure 2, was invented by Joseph R. Browning and his father (Fundamentals of Dimensional Metrology 3rd Ed p. 106). Browning went on to form Brown & Sharp Manufacturing Co., which today is one of the major manufacturers of measuring instruments and tooling. The Vernier caliper is one of the most versatile measuring tools used by engineers and machinists. The caliper can be used to measure the following features: linear distances / outside diameters, internal diameters, and depth.

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14

3. SURFACE TEXTURE MEASUREMENTS

3.1. Introduction

Although the term surface finish is frequently used to denote the general quality of a surface, it is not a technically accepted term. In fact, surface finish is a colloquial term widely used for qualitative assessment of a surface and is generally not quantified. Surface texture is the technically accepted term which is used to describe the repetitive or random deviations from the nominal surface which forms the three dimensional surface topography. Consider a surface as shown magnified in Figure 7. The predominant direction of the surface patter is called the lay and is usually determined by the production method. Occasionally an unintentional irregularity can occur in one spot or infrequent locations on the surface, this is called a flaw. Flaws can include such defects as cracks, inclusions, and scratches.

FIGURE 7. MAGNIFIED SURFACE

3.2. Texture Parameters

3.2.1. Curve Types

Currently there are over fifty parameters defined by various standards organizations, such as DIN, ISO, and JIS, to quantify the surface texture, they are based on curves derived from surface texture. Some of the most common parameters are described here.

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3.2.1.1. P-Curve (Unfiltered profile)

Consider the intersection of a surface and a plane normal to the surface and oriented such that the surface roughness Ra (to be explained later) is maximum. This is usually in a direction normal to the lay. The resulting profile shown in Figure 8 is called the P-Curve or unfiltered profile.

FIGURE 8. P-CURVE

3.2.1.2. R-Curve (Roughness profile)

Observations of the P-Curve often reveal the existence of low frequency component, If one removes all the low frequency components lees that a specified wavelength λc from the P-Curve the resulting curve shown in Figure 9 is called the R-Curve or the Roughness Profile. The wavelength λc is called the cutoff value.

FIGURE 9. R-CURVE

3.2.1.3. WC-Curve (Filtered waviness curve)

To obtain the R-curve the low frequency components were removed from the P-curve. If one does the opposite and removes the higher frequency components from the P-curve then the WC-curve or Filtered waviness curve is obtained as shown in Figure 10. The wavelength limit above which components are removed is called the high-band cutoff value (fh).

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FIGURE 10: WC-CURVE

These represent the basic types of curves; there are several others less commonly used.

3.2.2. Definition of Parameters

From the different curves one can obtain the parameters which are used to define the surface texture. As mentioned earlier there are many parameters to quantify the surface texture. Some of the most common ones will be explained in this lab as defined by the ISO and DIN.

3.2.2.1. Arithmetic Mean Deviation of the Profile (Ra)

Consider the roughness profile and place a straight line through it as shown in Figure 11 such that for some evaluation length lm the sum of the area above this line is equal to the sum of the area below the line. This line is called the center line.

FIGURE 11: ARITHMETIC MEAN DEVIATION OF PROFILE (RA)

If one considers the center line as the X-axis then let the roughness curve (R-curve) de defined by some function f(x). The arithmetic mean deviation is the mean of the absolute value of f(x) over the evaluation length lm as shown in Figure 12. It is sometimes called the Center Line Average (CLA) or the Arithmetic Average (AA Rating). It is given by the equation:

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FIGURE 12. FUNCTION F(X) OVER EVALUATION LENGTH LM

The evaluation length lm for calculating Ra is typically five times the cutoff value λc.

3.2.2.2. Average Peak-to-Valley Height (Rz (DIN))

Consider again the roughness profile. Taking a sampling length lm of five times the cutoff value λc, divide the roughness profile into five sections of equal sampling lengths (le) equal to the cutoff value λc as shown in Figure 13. Let Zi be defined as the difference between the highest peak and lowest valley in the ith sampling length. The Average Peak-to-Valley Height Rz (DIN) is defined as the average value of Zi for the five sampling lengths.

FIGURE 13. AVERAGE PEAK-TO-VALLEY HEIGHT RZ (DIN)

If there is not sufficient length on the surface for an evaluation length five times the cutoff value then an evaluation length of three times the cutoff value may be used but the sampling length must always be equal to the cutoff value.

3.2.2.3. Maximum Peak-to-Valley Height (Ry (DIN))

The Maximum Peak-to-Valley Height Ry (DIN) is defined as the maximum value of Zi used when calculating the Average Peak-to-Valley Height: RyDIN = ZiMAX

3.2.2.4. Average Peak-to-Valley Height (Rz (ISO))

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The ISO defines the Average Peak-to-Valley Height Rz (ISO) differently than DIN. Using the unfiltered profile (P-curve), place a line through it as shown in Figure 14, such that within the evaluation length the sum of the squares of the profile departures from this line is minimized.

FIGURE 14. AVERAGE PEAK-TO-VALLEY HEIGHT RZ (ISO)

Using the mean line the ISO defines the Average Peak-to-Valley Height Rz (ISO) and the difference between the average of the five highest peaks and the five lowest valleys measured from a reference line parallel to the mean line as shown in Figure 15.

FIGURE 15. AVERAGE PEAK-TO-VALLEY HEIGHT RZ (ISO)

3.2.2.5. Maximum Peak-to-Valley Height (Ry (ISO))

The ISO defines the Maximum Peak-to-Valley Height Ry (ISO)) as the distance between a line parallel to the mean line of the unfiltered profile (P-curve) passing though the highest peak and a line parallel to the mean line of the unfiltered profile (P-curve) passing through the lowest valley as shown in Figure 16.

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FIGURE 16. MAXIMUM PEAK-TO-VALLEY HEIGHT RY (ISO)

3.3. Standard Sampling and Evaluation Lengths

It should by now make sense that the sampling and evaluation lengths would vary depending on the magnitude of the parameters being measured. A “rough” surface would have longer sampling and evaluation lengths than a “smooth” surface. The following tables represent some standards used by the ISO and DIN.

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3.4. Specifying Surface Texture on a Drawing

On a technical drawing, when surface finish is important, it must be clearly indicated. The parameters presented to this point represent some of the most commonly used standards to describe surface texture. There are however some parameters which are not recognised by the ISO but are in common use such as the Waviness Width and the Waviness Height. Figure 17 describes the use of the surface finish symbols. The Roughness Height can also be expressed as a Roughness Grade. Figure 18 gives the Roughness Height associated with different Roughness Grades and typical applications. Figure 19 describes the machining processes which could be used to obtain different surface textures. Figure 20 describes how to represent the direction of the lay.

FIGURE 17. USE OF SURFACE FINISH SYMBOLS

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FIGURE 18. ROUGHNESS HEIGHT ASSOCIATED WITH DIFFERENT ROUGHNESS GRADES

22

Figure 18 (cont’d) Roughness Height associated with different Roughness Grades

FIGURE 19. SURFFACE FINISHESS OF DIFFERENT MACHINING PPROCESSES

2

23

24

FIGURE 20. LAY DESIGNATION SYMBOLS

3.5. Demonstration of Surface Texture Measurement

The student will observe the operation of the surface texture measurement machine by one of the EDML staff.

25

Measure Existing Gyroscope

Figure 22) you will be measuring has been manufactured by the EDML on numerical controlled machines. Now that you have been exposed to basic measuring principles, you are required to fill in the missing dimensions indicated on the attached sketches (Figure 24,

Figure 25 Figure 26). Be sure not to omit any dimensions, as you will be using your data to manufacture your own gyroscopes.

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FIGURE 21. GYROSCOPE

FIGURE 22. 3D MODEL OF GYROSCOPE

3.6. FILL IN MISSING DIMENSIONS

You will be provided with a digital Vernier caliper, Figure 23, due to time constraints and also for ease of use. You will use this measuring device to record all the missing dimensions on the sketches of the gyroscope.

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FIGURE 23. DIGITAL CALIPER (PICTURE COURTESY OF MACHINE MART)

For the next lab session, you will be required to make three detailed drawings of the frame, rotor, and shaft.

3.6.1. DO’S AND DON’TS OF USING A DIGITAL CALIPER Do:

• Treat your caliper with respect, as it is a delicate instrument

• Turn off caliper after use to preserve battery

• Place caliper in its protective case / box after use

• Unlock the set screw before opening the jaws

Don’t:

• Use your caliper as a scriber (i.e. to scratch or mark a surface)

• Drop or mistreat / abuse your caliper

• Force the jaws of the Vernier caliper open (check the set screw prior to use)

• Lay your caliper in a dangerous position, where it could fall

• Set it down in a dirty environment, as any foreign object debris (FOD) could damage the instrument, and subsequently your measurements.

• Lay your caliper in coolant as this will distort the measurements.

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FIGURE 24. SKETCH OF GYROSCOPE FRAME

Table 1. Dimensions for Gyroscope Frame

Dimension Value Dimension Value

1 16

2 17

3 18

4 19

5 20

6 21

7 22

8 23

9 24

10 25

11 26

12 27

13 28

14 29

15

29

FIGURE 25. SKETCH OF GYROSCOPE ROTOR

Table 2. Dimensions for Gyroscope Rotor

Dimension Value

1

2

3

4

5

6

7

8

30

FIGURE 26. SKETCH OF GYROSCOPE SHAFT

TABLE 3. DIMENSIONS FOR GYROSCOPE SHAFT

Dimension Value

1

2

3

4

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LAB 2 – 5 MACHINE TOOLS / GYROSCOPE MANUFACTURING

The following information is general information about all the machines and cutting tools used in the fabrication of the gyroscope. The procedure / steps on how to use the machine / fabricate the gyroscope will be demonstrated by the lab instructors. It is up to the students to take detailed notes and fill out their process sheets during each demonstration.

1. Process Plan for Machine Demonstration

The process plan of a work piece must be followed in order to machine a part. This plan has been determined by an engineer (in most cases there is a dedicated process planner), and is the most efficient order of operations. For further information on process plans, consult your course textbook.

A process sheet is to be filled out by the students during the demonstration for each part of the gyroscope (the frame, rotor, and shaft, and ring). The filled out process sheet will be used as a guide for students to follow while they machine their own parts. The EDML process sheet template can be found at: http://users.encs.concordia.ca/~dng

The formulas for the material removal rate (MRR), cutting time (CT), speeds and feeds are available in the course textbook. Be sure to record the material of the cutting tool and the workpiece as the material types affect the formulas / values to be used.

Note: The student will be required to make copies of this sheet, as only 1 part is to be listed per process sheet.

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2. The Engine Lathe

The engine lathe is one of the most common machines found in machine shops around the world. It can be used for turning, facing, drilling, boring, tapering, screw cutting, grinding, etc. The workpiece is held in place and rotated about its axis, while the cutting tool is fed along it. The engine lathe is usually found in schools or custom shops, where there is not a high volume production. For higher volume productions, shops would either use CNC lathes or turret lathes.

2.1. Safety on the Engine Lathe

• ALWAYS WEAR SAFETY GLASSES

• Do not operate a lathe unless you fully understand its controls and safety mechanisms. Be sure you can stop the machine quickly in case something happens.

• Only one person operates the machine at a time

• Never leave the chuck key in the chuck (If the key is in the chuck, your hand is on the key)

• Don’t wear any clothes or jewelry that may become entangled with the machine

• Make one full revolution of the workpiece to ensure it clears the cutting tools and the bed of the lathe

• Always use the brake (if applicable) to stop the rotating workpiece

• Never grab a rotating workpiece

• Do not leave rags in proximity to a lathe that is in operation – they may become snagged by the rotating parts

• Make sure the workpiece has come to a complete rest before attempting to approach the workpiece (to measure or to remove chips, etc.)

• Never remove chips by hand (very sharp) – use either a brush or pliers

• Keep work area tidy

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35

Metal Removal On The Engine Lathe

It should be noted that in order for metal cutting to occur, the workpiece must come in contact with the cutting surface of the tool. The figure below shows the convention used in the vast majority of cases: the workpiece rotates in a counterclockwise direction, when viewed from the tailstock. Two examples of when the convention does not apply (i.e. the workpiece must be rotated clockwise): if the tool is attached upside down, or if the tool is fed from the right side of the workpiece, as seen from the tailstock. If the workpiece is rotated in the wrong direction and the tool is fed into it, a loud squealing noise will occur, followed by the breaking of the tool bit.

FIGURE 30. METAL REMOVAL ON LATHE (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)

2.1.3. Cutting Speed And Feed Calculations On The Engine Lathe

TABLE 4. LATHE CUTTING SPEEDS USING HSS CUTTING TOOL (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)

Material Turning and Boring Threading Rough Cut Finish Cut

ft/min m/min ft/min m/min ft/min m/min Machine Steel 90 27 100 30 35 11 Tool Steel 70 21 90 27 30 9 Cast Iron 60 18 80 24 25 8 Bronze 90 27 100 30 25 8

Aluminum 200 61 400 93 60 18

TABLE 5. FEEDS FOR VARIOUS MATERIALS USING HSS CUTTING TOOL (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)

Material Rough Cuts Finish Cuts in / rev mm /rev in / rev mm /rev

Machine Steel .010-.020 0.25-0.5 .003-.010 0.07-0.25

Tool Steel .010-.020 0.25-0.5 .003-.010 0.07-0.25 Cast Iron .015-.025 0.4-0.65 .005-.012 0.13-0.3 Bronze .015-.025 0.4-0.65 .003-.010 0.07-0.25 Aluminum .015-.030 0.4-0.75 .005-.010 0.13-0.25

36

The feed is directly selected on the headstock of the engine lathe and is expressed in units of distance per revolution.

To determine the spindle speed (in r/min), the cutting speed, diameter of the workpiece, the material of the tool bit and the workpiece, and the type of operation (roughing, finishing, or threading) must be known. These parameters can be in either Imperial or SI units; however the formulas for calculating the spindle speed varies slightly for each system of units.

2.1.3.1. Inch Calculations

The formula to calculate the spindle speed using Imperial units is:

1

12DVN

π= or r/min= (CS*12) / (π*D)

where V, CS = cutting speed (ft/min)

D, D1 = diameter of work to be turned (in)

A simpler formula is commonly used because many lathes offer a limited choice of speed settings. It is also used for ease of calculation. This formula is:

1

4DVN = or r/min= (CS*4) / (D) or RPM=

DCS 4*

2.1.3.2. Metric Calculations

The formula to calculate the spindle speed using Metric units is:

1

320D

VN = or r/min= (CS*320) / (D)

where V,CS = cutting speed (m/min)

D, D1 = diameter of work to be turned (mm)

2.1.4. Types Of Cutting Tools You Will Use On The Engine Lathe

• Turning tool bits

These are typical high speed steel (HSS) tool bits used on the engine lathe. Note that each one below has different features related to its intended purpose.

37

FIGURE 31. TURNING TOOL BITS (WWW.VARMINTAL.COM)

• Twist drill

Twist drills are end cutting tools used to produce holes in many materials. Drills are categorized in four systems: fractional, number, letter, and metric.

• Fractional size drills range from 1/64” to 4” in diameter

• Number size drills range from #1 (.228”) to #97 (.0059”)

• Letter size drills range from A (.234”) to Z (.413”)

• Metric drills range from 0.04 mm to 80 mm.

FIGURE 32. TWIST DRILL (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

38

• Center drill

The center drill is defined by its length (l1), and the two diameters (d1 and d2). It is used to spot the location for a hole as it is very rigid and has a small web. A center drill must be used before using a twist drill; else the drill will “wander” across the surface, resulting in a misshapen hole.

FIGURE 33. CENTER DRILL (WWW.GREENWOOD-TOOLS.CO.UK)

• Reamer

Reamers are used to finish pre-existing holes to an accurate dimension. They remove only a very small amount of material. The following are guidelines for material removal for reamers:

Nominal Size Suggested Depth of Cut

≤ 1/4” .010”

≤ 1/2” .016”

≤ 1” .020”

FIGURE 34. REAMER (EFUNDA.COM)

39

2.1.5. Types Of Work Piece Holders

• 3-Jaw chuck

The 3-jaw chuck is the most versatile workholding device used on the engine lathe. It has the ability to center the workpiece automatically, and all 3 jaws can be actuated by using the key in one of the three key holes.

FIGURE 35. 3-JAW CHUCK (WWW.MICROMEX.COM.MX)

• Spring collet

Collets are used to hold smooth workpieces with greater centering accuracy than conventional chucks. Also, there are no clamping marks left on the surface of the workpiece, as it is uniformly held in place by the collet.

FIGURE 36. SPRING COLLET (WWW.JJJTRAIN.COM)

40

FIGURE 37. COLLET ATTACHED IN HEADSTOCK (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

2.1.6. Processes To Be Performed by the Student on The Engine Lathe

• Facing

Facing is accomplished by turning the cross-slide handle so that the cutting tool moves to cut and level the end of the work piece.

FIGURE 38. FACING (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

41

Turning

Turning is the process whereby metal is removed from the surface parallel to the axis of rotation, while the tool bit is fed along the work piece.

FIGURE 39. TURNING (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

• Drilling

Twist drills are end cutting tools used to produce holes in many materials. They are attached in the tailstock by means of a taper or a chuck, and held stationary. The operator advances the drill into the workpiece via the tailstock handwheel.

FIGURE 40. TURNING (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

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43

3. The Vertical Milling Machine

3.1. Safety on the Vertical Mill

• ALWAYS WEAR SAFETY GLASSES

• Do not operate a mill unless you fully understand its controls and safety mechanisms. Be sure you can stop the machine quickly in case something happens.

• Only one person operates that machine at a time

• Don’t wear any clothes or jewelry that may become entangled with the machine

• Ensure the wrench is never left on the top of the machine when changing chucks

• Before starting machine, ensure that the High / Low gear selector is properly engaged

• Always use the brake to slow down the rotating cutter

• Never grab a rotating cutter

• Make sure the cutter has come to a complete rest before removing chips

• Never remove chips by hand (very sharp) – use either a brush or pliers

• Keep work area tidy

3.2. Nomenclature of the Vertical Mill

FIGURE 42. VERTICAL MILL NOMENCLATURE (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

44

3.2.1. How Vertical Mills Are Specified

• Work piece envelope: Maximum size of piece that can fit on the machine. Expressed in three coordinates (X, Y, Z).

• Horsepower: This dictates basically how much material you can remove in a given time. Higher the HP, the larger the Material Removal Rate (MRR).

3.2.2. Axes of Vertical Mill

FIGURE 43. AXES OF A VERTICAL MILL

3.2.3. Metal Removal On The Vertical Mill

3.2.3.1. Climb Milling

In climb milling (down milling), the cutter rotation is in the same direction as the feed rate. The main difference in the two types of milling is the chip formation – more detail will be provided in the class lectures.

45

FIGURE 44. CLIMB MILLING (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)

3.2.3.2. Conventional Milling

In conventional milling (up milling), the cutter rotates against the direction of feed of the workpiece. Due to limitations of the machine, you must take care to ensure that you only use conventional milling.

FIGURE 45. CONVENTIONAL MILLING (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)

3.2.4. Cutting Speed Calculations on the Vertical Mill

To determine the spindle speed (in r/min), the cutting speed and circumference of the cutter must be known. These parameters can be in either Imperial or SI units; however the formulas for calculating the spindle speed varies slightly for each system of units.

46

TABLE 6. MILLING MACHINE CUTTING SPEEDS (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)

400‐1000

47


The formula to calculate the spindle speed using Imperial units is:

DVNπ

= or r/min= (CS) / (circumference)

where V,CS = cutting speed (ft)

circumference = circumference of cutter (in)

D = diameter of cutter (in)

N = RPM of cutting tool

DVN

π12

= or r/min= (12 * CS) / (π * D)

A simpler formula is commonly used because 12 / π ≈ 4. This formula approximates to:

DVN 4

= or r/min= (CS*4) / (D)


The formula to calculate the spindle speed using Metric units is:

DVN

π1000

= or r/min= (CS * 1000) / (π * D)

where V,CS = cutting speed (m)

D = diameter of cutter (mm)

N = RPM of cutting tool

This reduces to:

DVN 320

= or r/min= (CS*320) / (D)

48

3.2.5. Feed Calculations on the Vertical Mill

The milling feed is the rate at which the work is fed into the milling cutter.

TABLE 7. RECOMMENDED FEED PER TOOTH FOR HSS CUTTERS (TECHNOLOGY OF MACHINE TOOLS 5TH ED.)


The formula to calculate the feed using Imperial units is:

Feed = n * CPT * r/min or Nnff tm =

Where

Feed, fm = feed of workpiece (in/min)

n = number of teeth in the milling cutter

ft, CPT = chip per tooth for a particular cutter and metal (found in tables)

N, r/min = revolutions per minute of the milling cutter


The formula to calculate the feed using Metric units is:

Nnff tm = or Feed = N * CPT * r/min

where fm = feed of workpiece (mm/min)

n = chip per tooth for a particular cutter and metal (found in tables)

N, r/min = revolutions per minute of the milling cutter

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50

FIGURE 47. TWIST DRILL (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

• Center drill

The center drill is defined by its length (l1), and the two diameters (d1 and d2). It is used to spot the location for a hole as it is very rigid and has a small web. A center drill must be used before using a twist drill; else the drill will “wander” across the surface, resulting in a misshapen hole.

Figure 48. Center Drill (www.greenwood-tools.co.uk)

3.2.7. Types of Work Piece Holders

• Vise

Vises are used to clamp workpieces securely while milling. The vises are attached to the table of the mill.

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53

4. General Machine Shop Machines

Drill Press

Drill presses are commonly used in machine shops. The drill bit is held in place by the chuck, and is lowered into the workpiece (being held stationary on the table with a vise) by means of the capstan wheel. The table can be raised or lowered, depending on the height of the part to be drilled.

4.1.1. Drill Press Nomenclature

FIGURE 51. DRILL PRESS (MATERIALS AND PROCESSES IN MANUFACTURING 9TH ED.)

4.2. Hand Tools

In addition to the many machines used in the EDML, a variety of hand tools are used as well.

4.2.1. Taps

Taps are used to make internal threads on a part. They can be done either by hand or on a machine, but for the purpose of this lab we will deal only with hand taps.

A hole of diameter slightly larger than the minor diameter of the thread must already exist. The thread profile is created by the cutting edges of the flutes; the flutes also provide space for lubrication and chip removal. Tap oil must be used, as taps create a lot of friction and are prone to breaking.

The table below, called a Tap / Drill Size Chart, is a very useful tool when designing interior threaded parts. It tells the user that in order to tap threads of a certain size, the pre-existing hole of a corresponding diameter

54

must already exist. For example, to tap internal threads of ¼-28 NF, the #3 drill must be used, which corresponds to 7/32”.

TABLE 8. TAP / DRILL SIZE CHART

To Tap This Size Screw Or Bolt: Use This Drill Bit: (Closest Fractional:) Decimal Inches 0-80 NF 3/64" 3/64" .0469 1-64 NC #53 - .0595 1-72 NF #53 1/16" .0595 2-56 NC #50 - .0700 2-64 NF #50 - .0700 3-48 NC #47 5/64" .0785 3-56 NF #45 - .0820 4-36 NS #44 - .0860 4-40 NC #43 3/32" .0890 4-48 NF #42 3/32" .0935

3mm-.060mm 2.5mm - .0984 1/8-40 NS #38 - .1015 5-40 NC #38 - .1015 5-44 NF #37 - .1040 6-32 NC #35 7/64" .1100 6-36 NS #34 - .1110 6-40 NF #33 - .1130 6-48 NS #31 - .1200

4mm-0.70mm 3.4mm - .1338 4mm-.075mm 3.4mm - .1338

8-32 NC #29 - .1360 8-36 NF #29 9/64" .1360 8-40 NS #28 - .1405

3/16-24 NS #26 - .1470 10-24 NC #25 5/32" .1495

3/16-32 NS #22 - .1570 10-32 NF #21 5/32" .1590

5mm-.090mm 4.2mm - .1653 5mm-.080mm 4.3mm - .1693

12-24 NC #16 11/64" .1770 12-28 NF #14 3/16" .1820

12-32 NEF #13 - .1850 14-20 NS #10 - .1935 1/4-20 NC #7 13/64" .2010 14-24 NS #7 - .2010

6mm-1.00mm 5.2mm - .2047 1/4-24 NS #4 - .2090 1/4-28 NF #3 7/32" .2130

1/4-32 NEF 7/32" 7/32" .2188 1/4-40 NS #1 - .2280

7mm-1.00mm 6.1mm 15/64" .2401 5/16-18 NC Ltr. ‘F’ 17/64" .2570

8mm-1.25mm 6.9mm 17/64" .2716 5/16-24 NF Ltr. ’I‘ - .2720

8mm-1.00mm 7.1mm - .2795 5/16-32 NEF 9/32" 9/32" .2812 9mm-1.25mm 7.9mm - .3110

3/8-16 NC 5/16" 5/16" .3125 9mm-1.00mm 8.1mm - .3189

55

9mm-0.75mm 8.3mm - .3268 3/8-24 NF Ltr. ‘Q’ 21/64" .3320

10mm-1.50mm 8.7mm - .3425 10mm-1.25mm 8.9mm 11/32" .3503 10mm-1.00mm* 9.1mm - .3583

7/16-14 NC Ltr. ‘U’ 23/64" .3680 11mm-1.50mm 9.7mm - .3818

7/16-20 NF 25/64" 25/64" .3906 12mm-1.75mm 10.5mm - .4133 12mm-1.50mm 10.7mm 27/64" .4212

1/2-13 NC 27/64" 27/64" .4219 12mm-1.25mm* 10.9mm 27/64" .4291

1/2-20 NF 29/64" 29/64" .4531 1/2-24 NS 29/64" 29/64" .4531

14mm-2.00mm 12.2mm - .4803 9/16-12 NC 31/64" 31/64" .4844

14mm-1.50mm 12.7mm - .4999 14mm-1.25mm* 12.8mm - .5039

9/16-18 NF 33/64" 33/64" .5156 5/8-11 NC 17/32" 17/32" .5312

16mm-2.00mm 14.2mm 35/64" .5590 5/8-18 NF 37/64" 37/64" .5781

16mm-1.50mm 14.7mm - .5787 11/16-11 NS 19/32" 19/32" .5938

18mm-2.50mm 15.8mm 39/64" .5220 11/16-16 NS 5/8" 5/8" .6250 3/4-10 NC 21/32" 21/32" .6562

18mm-1.50mm* 16.8mm - .6614 3/4-16 NF 11/16" 11/16" .6875

20mm-2.50mm 17.8mm 11/16" .7008 7/8-9 NC 49/64" 49/64" .7656 7/8-14 NF 13/16" 13/16" .8125

22mm-1.50mm 20.9mm - .8228 7/8-18 NS* 53/64" 53/64" .8281

24mm-3.00mm 21.4mm 53/64" .8425 1.8 NC 7/8" 7/8" .8750

24mm-2.00mm 22.3mm - .8779 1.12 NF 59/64" 59/64" .9219 1-14 NS 15/16" 15/16" .9375

1 1/8-7 NC 63/64" 63/64" .9844 1 1/8-12 NF 1 3/64" 1 3/64" 1.0469 1 1/4-7 NC 1 7/64" 1 7/64" 1.1094 1 1/4-12 NF 1 11/64" 1 11/64" 1.1719 1 3/8-6 NC 1 7/32" 1 7/32" 1.2188 1 3/8-12 NF 1 19/64" 1 19/64" 1.2969 1 1/2-6 NC 1 11/32" 1 11/32" 1.3438

1 1/2"-12 NF 1 27/64" 1 27/64" 1.4219

56

5. How to Fill Out an Inspection Report

Once you have completed manufacturing a component of the gyroscope, you must now verify your work and fill out an inspection report for that part.

5.1. Description of Inspection Report

• No.: Feature number of each part (corresponds to numbers on the sketches).

• Dwg. Dimension: Dimension of feature (from detailed drawing)

• Tolerance: Tolerance of feature if applicable (from detailed drawing)

• Actual Measurement: Measured value of the feature on the machined part

• Accept: Either yes or no, depending if the feature is within specification

• Reject (OHL or ULL): If the feature is rejected, indicated either how much over the high limit it is (OHL) or how much under the low limit it is (ULL)

• Comments: Why the part was rejected, what caused error, etc.

Use the attached sketches for reference in filling out the inspection reports.

FIGURE 52. SKETCH OF GYROSCOPE FRAME

57

FIGURE 53. SKETCH OF GYROSCOPE ROTOR

FIGURE 54. SKETCH OF GYROSCOPE SHAFT

58

LAB 6 – GYROSCOPE ASSEMBLY / CNC ENGRAVING / WELDING GYROSCOPE STAND / POLISHING

1. Computer Numerical Controlled (CNC) Engraving of Gyroscope Frame

The student will be able to engrave writing on their gyroscope by using the CNC milling machine in the EDML A area. The current semester and the year will be engraved on the gyroscope frame. Students will be able to see how a CNC program is made from a CAD drawing and watch the code being executed by the machine on their frame.

1.1. CNC Vertical Center

Figure 55 is a picture of a CNC vertical center or a CNC milling machine. This machine has all the same axes of a conventional vertical milling machine. Most CNC machines are enclosed to prevent the operator from being injured, as well as to enable coolant to be sprayed over the entire work area. Notice the computer screen attached to the machine. This is known in industry as the controller. The programmer would program the part required in the controller and monitor the status of the part during machining operations. Some CNC machines, like the one pictured below have automatic tool changers. This eliminates the need for an operator during the machining cycle as the machine can change to the required tool itself.

FIGURE 55. CNC VERTICAL CENTER (MILL)

59

A tool changer like the one in Figure 56 below consists of a carousel (or two) of various tools ready to be installed in the spindle of the machine upon request from the program. The tools that are loaded in the carousel are determined by the technician operating the machine and vary from job to job. When the program requests a tool change, the spindle stops, orientates and locks, then the tool carousel is rotated to a location where there is currently no tool. The current tool in the spindle is removed and placed into the empty space. The carousel is then rotated to the designated tool position and the new tool is installed in the spindle. This usually happens in a period of no more that 10 seconds.

FIGURE 56. AUTOMATIC TOOL CHANGER (WWW.HARDINGE.COM)

Another nice feature of CNC machines is that you can control all three axes at a given time. This means you can create accurate radii, curves, ramped surfaces or complex 3-dimensional surfaces. All of the above would not be able to be created on a conventional machine tool. Some more expensive CNC machines can control up to five axes simultaneously. Figure 57 below illustrates the five different axes which can be controlled at the same time.

FIGURE 57. AXES OF A MACHINING CENTER (MILL)

Figure 58 is a Computer Aided Manufacturing example of how controlling all five axes at the same time may be useful. This manufacturing simulation is of an impeller. Note the complex end mill path.

60

FIGURE 58. TURBINE IMPELLER (WEST-GMBH.DE)

61

1.2. CNC Lathe

The CNC lathe is similar to all other CNC equipment where all the axes can be controlled at the same time. The CNC lathe has also the ability to change tools on its own. The CNC lathe can make very complex parts that are not able to be made on conventional machines. A typical CNC machine is pictured below (Figure 59).

FIGURE 59. CNC LATHE

A very nice feature which some CNC lathes have is the ability to control a third or fourth axis. The part can be stopped from rotating and “live tooling” can be used to radially and axially machine pockets. An example of a CNC three axis lathe operation is pictured below (Figure 60).

FIGURE 60. THIRD AXIS CNC LATHE MACHINING OPERATION

62

1.3. CNC Programming Language

The program language used by CNC machines has been fairly standardized. It is known as G and M code programming. Some companies however have built in software in the controllers of the CNC machines which works based on a graphical interface. Basically this means that you can draw the part on the controller and the controller will convert your drawing into G and M code and subsequently machine your part. Within the past ten years, Computer Aided Manufacturing has been playing a huge role in manufacturing. Computer Aided Manufacturing software can analyze a part drawn in AutoCAD or CATIA, etc. and generate the proper G and M codes for the part. You can even simulate the whole machining process on your screen where you see the movement of each cutting tool in relation to the workpiece. A standard G and M code description is provided below. Note that these are standard codes and some machines have codes specific to themselves.

1.3.1. G & M CODE COMMAND SUMMARY

Preparatory Command (G-Codes) Miscellaneous Functions (M-Codes)

G00 Rapid positioning move M00 Temporary stop

G01 Linear cutting move M02 End of program stop

G02 Clockwise circular cutting move M03 Spindle <ON> CW (output #1)

G03 Counterclockwise circular cutting move M04 Spindle <ON> CCW (output #5)

G28 Set system or user defined variable to value M05 Spindle <OFF> (output#1, output#5)

G81 Canned threading cycle M06 Tool change

G70 Set inch programming (default) M08 Coolant <ON> (output #2)

G71 Set metric programming M09 Coolant <OFF> (output #2)

G90 Set absolute programming mode M30 End program

G91 Set incremental programming mode (default) M39 Chuck <CLOSE> (output #6)

M40 Chuck <OPEN> (output #6)

Special Codes M99 Restart part program from beginning

* Multiplies two variables

F Feed rate

S Spindle speed

T Tool number

FIGURE 61. G AND M CODE FUNCTIONS (WWW.MICROKINETICS.COM/ TMPRO.HTM)

63

With the above codes one could write their own CNC program control. An example of one such program is as pictured below. Note the N5, N10, N15, etc. are used to denote the lines of the program. Each line of the program is called a block.

N5 G0 X0.5 Y0.5 (THE CUTTER MOVES FROM THE ZERO POSITION TO THE BOTTOM LEFT CORNER OF THE SQUARE)

N10 G1 Z-.125 F20 (THE CUTTER PLUNGES 1/8" INTO THE MATERIAL AT 20 INCHES PER MINUTE)

N15 Y1.0 (THE CUTTER TRAVELS TO Y 1.0)

N20 X1.0 (TO X 1.0)

N25 Y0.5 (TO Y 0.5)

N30 X0.5 (TO X 0.5)

N35 Z.125 (RAISES UP TO 1/8" ABOVE THE MATERIAL)

N40 G0 X0.0 Y0.0 (RETURNS BACK TO THE START POINT)

FIGURE 62. BASIC CNC PROGRAM

64

2. Welding Gyroscope Stand

Students will also be able to fabricate a stand for the gyroscope using a GMAW welding process. The stand will consist of three parts that will be held in a welding fixture to assure consistency and repeatability. See figure 65 below for the welding drawing of the gyroscope stand.

Figure 63 ‐ Gyroscope Stand

65

2.1. Welding Safety

• Welding and brazing causes harmful ultraviolet light, radiation and high heat. Do not look at the light from welding or brazing without wearing the proper welding mask. You will cause damage to your eyes even if you catch a flash of light from welding.

• Welding and brazing causes harmful fumes, only weld or brazing with proper ventilation turned on.

• Welding and brazing causes sparks of molten metal; ensure that you have the proper clothing if you are near someone welding.

• Welding and brazing cause large amounts of heat build-up which last a long time in the workpiece, table, welding gun, etc. Make sure you handle all the parts and tools with proper gloves and take care not to lean, step on or pick-up any hot parts

• Welding uses high voltage! Ensure that you are not touching any part of the electrode before you start welding.

• Proper safety equipment is needed when welding, which includes:

o Apron

o Helmet (with proper shade of lens)

o Safety glasses

o Gloves

o Proper ventilation

Time permitting; you will receive a demonstration of the following joining processes:

- Brazing

- Gas Tungsten Arc Welding

- Gas Metal Arc Welding

- Shielded Metal Arc Welding

66

2.2. Gas Metal Arc Welding (GMAW)

Gas Metal Arc Welding (GMAW) is also commonly referred to as Metal Inert Gas Welding. (MIG). GMAW is known for its extremely high metal deposition rates, and is used in high production environments. The filler material is fed through the torch or gun and also acts as the electrode (consumable). The electrode, like GTAW, is shielded by an inert gas, usually CO2 or Argon. The filler material depends on the application and varies widely.

FIGURE 64. GMAW PROCESS (WELDINGENGINEER.COM)

67

2.3. Brazing

Brazing is a process where unlike welding, the base metals are not melted and fused together. Brazing uses a filler metal which when heated with the base metal is sucked into the base metal through capillary action. These filler metals are typically an aluminium silicon copper alloy or a silver alloy, but it should be noted that there are many other filler materials depending upon the application.

FIGURE 65. BRAZING (LUCASMILHAUPT.COM)

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Gas Tungsten Arc Welding (GTAW)

Gas Tungsten Arc Welding (GTAW) is also commonly referred to as Tungsten Inert Gas Welding (TIG). GTAW is frequently used when high quality, high precision, low volume welds are needed. The reason for this is because GTAW requires skill and the process itself if not conducive to high volume production (GTAW has a low metal deposition rate). In GTAW, an electric arc is formed between a tungsten electrode (non-consumable) and the workpiece. Inert gas (Argon or Argon-Helium) is fed from the welding torch around the electrode to prevent air from coming in contact with the molten metal, which would cause oxidation and thus resulting in poor quality welds.

FIGURE 66. GTAW PROCESS (WELDINGENGINEER.COM)

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2.4. Shielded Metal Arc Welding (SMAW)

Shielded Metal Arc Welding (SMAW) is also commonly referred to as stick or arc welding. This welding process is the most widely used of all the welding processes. This is due to the fact that it requires minimal investment for a machine; as well, the consumables are not very expensive. SMAW uses a rod covered with a flux; this is the consumable electrode. Once the electrode comes in contact with the workpiece, the filler metal, flux, and base metal (workpiece) are all melted together. The flux, being lighter than the base or filler metal floats to the top of the molten metal and creates a slag which shields the molten metal from the surrounding air (to prevent oxidization). Once the weld has cooled, the welder must chip off the slag.

FIGURE 67. SMAW PROCESS (WELDINGENGINEER

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3. Polishing of Gyroscope Frame

Students will also be able to decrease the surface roughness of their frame while being able to achieve a mirror like finish. It is recommended that the student first measure the surface roughness of their frame before they start polishing as to have a starting surface roughness value to compare the final result to. The polishing procedure starts with wet sanding on a pane of glass over a sink. Various grits of sand paper are used in increasing order to sand away any imperfections on the frame’s surface. The student will start at 120 grit, then 240, and at last 600 grit sandpaper. The longer the students sands at each step, the better the overall surface finish will be achieved. Once the sanding step is done, the student will proceed to polish their frame using an aluminum billet polish compound. The compound will be rubbed into the surface of the frame using a piece of rubber until a black haze appears. Once the haze is uniform on both side of the frame, the student will use a terry cloth and buff the haze off the frame resulting in a mirror like finish. The final step is to verify the surface roughness by using one of the Mitutoyo surface measurement machines and compare it to the initial value.

4. Gyroscope Assembly

Now that you have completed machining the gyroscope components, you must now assemble the components. You will be given a drawing of the assembled Gyroscope (Figure 69 below).

Assembly drawings vary greatly in the amount and type of information they give, depending on the type of mechanism they describe. The main functions of the assembly drawing are to show the product in its completed shape, to show the relationship between its various components, and to designate these components by a part or detail number. Other information that might be given includes overall dimensions, relationship dimensions between parts (necessary information for assembly), operating instructions, and data on design characteristics. The weight can also be included, and this information can be useful when calculating packaging or shipping requirements. Assembly drawings never have detailed dimensions unless it is required for an assembly. For example, if during assembly you have to press a bearing onto a shaft without a shoulder, the distance that the bearing must be pressed onto the shaft will be noted.

Usually on assembly drawings there is a table. This table is known as the bill of materials. A bill of materials is a must for every assembly and is either on the assembly drawing or attached as a separate sheet. The bill of materials is used to determine how many parts the assembly is made up of and the name, description and drawing number of those parts (if the parts are manufactured in house) or name, description and supplier name and catalogue number (if the parts are purchased).

For example, Company X places an order for 500 Gyroscopes, they would look at the assembly drawing and figure out how many of each components they would need (1000 #8-32 nuts, 500 rotors, etc). They would also be able to determine which detailed drawings we would need to start production and pull them from filing or the computer (D-01, D-05, etc.). Any purchased parts as indicated in the bill of materials can be sent out for quote. Once all the information is gathered from the assembly drawing, the production engineer can give an estimated cost and manufacturing time to the customer.

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Figure 68 below is an example of a more complex assembly, something that you might be more likely to see in industry. Note that this assembly has several views including an isometric and a section view due to its complexity. In our case, as the gyroscope is a relatively simple assembly, we will only need one view.

FIGURE 68. DETAILED ASSEMBLY DRAWING (HTTP://WWW.PROFILESMAGAZINE.COM/P19/TIPS-DESKTOP-PG1.HTML)

Figure 69 is the assembly drawing of the gyroscope. Note that in the upper left hand side of the drawing all the components required are listed, as well as their respective quantities. A full page landscape drawing will be provided for you at the end of this manual.

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FIGURE 69. ASSEMBLED GYROSCOPE – SAMPLE DRAWING

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6. Rapid Prototype Demonstration

With increasing costs of manufacturing, engineering departments are being forced to use less machining resources to develop their projects. They want to machine their prototype once and know that it will all fit together and work as designed. This is where rapid prototyping comes into play. Most major engineering design companies have these machines located on their premises. There are many different process used to create rapid prototypes. Some of these processes are:

- Stereolithography

- Selective Laser Sintering

- Paper Lamination Technology

- Fused Deposition Method

- 3D Printing

We will focus on the starch deposition method as this is the type of machine that Concordia University owns.

FIGURE 70. 3D PRINTER (Z-CORPORATION)

With the machine pictured in Figure 70 engineers are able to turn complex CAD drawings into real life three dimensional objects within hours. All rapid prototype machines recognize a standard solid model extension format. These models have a .stl file name and are used for rapid prototyping. An example of a complex rapid prototyped assembly is shown below (Figure 71).

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FIGURE 71. COMPLEX RAPID PROTOTYPED PART

If the above part was sent to a machine shop to be made out of metal, this would be very costly and require a lot of time to make. This would be even more costly if there was an error in the design and a revision of the part was required. Within a short period of time an engineer can have his or her part made from a polymer. The part is the actual size, and can be used for actual size mock-up and assembly. The rapid prototyped part would have cost a fraction of the cost if it were to be machined. If a revision of the design is required, the new part can be rapid prototyped without the costs and delays of having it machined.

The 3D printing method works as follows. A thin layer of starch is placed and rolled flat on a moving platform. An inkjet print head then moves over the profile of the part and dispenses a liquid which solidifies the starch. The moving platform is then lowered by a small increment and a new layer of starch is placed on the moving platform. The inkjet print head then moves over the profile again building the part by a thin slice of starch at time. Once the part is finished, it is removed leaving the unhardened starch behind.

FIGURE 72. HOW THE 3D PRINTER WORKS (CADCAM.NET)

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For a process sheet template, title block template, inspection sheet template and examples of how to fill them out, please refer to the following webpage:

http://users.encs.concordia.ca/~dng/edml/

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