Milling Machine Operations - NEMESneme-s.org/CTHSS/Machining Fundamentals/MFIM18.pdfMilling Machine Operations LEARNING OBJECTIVES After studying this chapter, students will be able

INSTRUCTIONAL MATERIALSText: pages 317–352

Test Your Knowledge Questions, pages351–352

Workbook: pages 99–106Instructor’s Resource: pages 239–252

Guide for Lesson PlanningResearch and Development IdeasReproducible Masters:

18-1 Mounting End Mills18-2 Using the Edge Finder18-3 Efficiency of Small Diameter Cutter18-4 Straddle Milling18-5 Types of Gears18-6 Gear Nomenclature18-7 Bevel Gear Nomenclature18-8 Test Your Knowledge Questions

Color Transparencies (Binder/CD only)

GUIDE FOR LESSON PLANNINGDue to the amount of material covered, it

would be advisable to divide this chapter intoseveral segments. Although it has been dividedinto five parts here, each classroom situationwill dictate what division would work best.

While covering each segment of this chapter,continually emphasize the safety precautionsthat must be observed when operating millingmachines.

Part I—Vertical Milling MachineHave the class read and study pages

317–328, paying special attention to the illustra-tions. Review the assignment using Repro-ducible Masters 18-1 and 18-2 as overheadtransparencies and/or handouts. Discuss ordemonstrate the following:

• Parts of the vertical milling machine.• Cutters for vertical milling machines.• Vertical milling machine operation.• Methods employed to mount cutters. Use

Reproducible Master 18-1.• Methods used to align a vise.• Demonstrate how to align a vise with a

dial indicator.• Mounting work in a vise.• Squaring stock with a vertical milling

machine.

Chapter 18

Milling MachineOperations

LEARNING OBJECTIVESAfter studying this chapter, students will be able to:� Describe how milling machines operate.� Set up and safely operate horizontal and vertical milling machines.� Perform various cutting, drilling, and boring operations on a milling machine.� Make the needed calculations and cut spur gears.� Make the needed calculations and cut a bevel gear.� Point out safety precautions that must be observed when operating a

milling machine.

239

• Machining angular surfaces.• Positioning a cutter to mill a keyway or

slot.• Demonstrate how to use a wiggler.• Demonstrate how to use an edge finder.

Use Reproducible Master 18-2.• Boring on a vertical milling machine.• Milling machine care.

Part II—Horizontal Milling MachineOperations

Have the class read and study pages 328–339paying particular attention to the illustrations.Review the assignment using ReproducibleMasters 18-3 and 18-4 as overhead transparenciesand/or handouts. Discuss or demonstrate thefollowing:

• Milling flat surfaces.• Why the smallest diameter cutter that will

do the job should be used.• How to position a cutter using a paper

strip.• Face milling.• Side milling.• Straddle and gang milling.• How to position a side cutter to mill a slot

in flat stock.• How to position a side cutter to mill a slot

or keyway in round stock.• Slitting and slotting operations.• Drilling and boring on a horizontal

milling machine.• How to align an existing hole for boring.• Care and cleaning of a horizontal milling

machine.

Part III—Cutting a Spur GearA selection of gears, dividing head and gear

cutters should be available for examination.Have students read and study pages 340–346,

paying particular attention to the illustrations.Review the assignment using ReproducibleMasters 18-5 and 18-6 as overhead transparenciesand/or handouts. Discuss or demonstrate thefollowing:

• Gear nomenclature.• How to determine the correct gear cutter.• Calculating the information necessary to

cut a gear.

• Preparing the dividing head to cut therequired number of teeth.

• How to center the gear cutter on thework.

• Cutting the gear.• How gear teeth measurement is checked.

Part IV—Cutting a Bevel GearAn assortment of bevel and miter gears

should be available for examination.Copy and distribute Reproducible Master

18-7. Explain how cutting a bevel gear is a muchmore complex operation than cutting a spurgear. Before studying the segment on how to cuta bevel gear, allow students/trainees to examineand compare bevel and spur gears. Hold anopen discussion emphasizing the differencesbetween the two.

Have students read and study pages346–349, paying particular attention to the illus-trations. Review the assignment and discuss thecomplexity of cutting a bevel gear with accuracy.

Part V—Industrial Applications of MillingMachines

Using the illustrations on pages 350 and 351,point out the variety of milling machine types.Point out how the machine in Figure 18-98 isradically different.

Many companies are willing to provide edu-cational materials in the form of press kits.Obtain as much information on new millingmachines as possible. In addition to printedmaterials, request any available photographs,slides or videos. These materials are also avail-able at annual trade shows.

Technical TermsReview the terms introduced in the chapter.

New terms can be assigned as a quiz, home-work, or extra credit. The following list is alsogiven at the beginning of the chapter.

addendumbevel gearcircular pitchdedendumdiametral pitchgang millingslittingslottingspur gearstraddle milling

Machining Fundamentals Instructor’s Resource240

Review QuestionsAssign Test Your Knowledge questions. Copy

and distribute Reproducible Master 18-8 or havestudents use the questions on pages 351–352 andwrite their answers on a separate sheet of paper.

Workbook AssignmentAssign Chapter 18 of the Machining Funda-

mentals Workbook.

Research and DevelopmentDiscuss the following topics in class or have

students complete projects on their own.1. Prepare a video or slide presentation illus-

trating the safety precautions that must befollowed when operating a vertical millingmachine.

2. Demonstrate how to use a wiggler and edgefinder.

3. Demonstrate how boring is done on a verti-cal milling machine.

4. Demonstrate how to center a cutter onround stock for milling a keyseat. Use thepaper strip technique.

5. Overhaul and paint a milling machine inyour training facility.

6. Demonstrate how to cut a spur gear.7. Demonstrate how to machine helical gears.8. Present a video on CNC milling machines.

Lead the discussion on what was seen.9. Develop a simple project to be made by an

NC or CNC milling machine. Prepare theprogram to do the job.

TEST YOUR KNOWLEDGEANSWERS, Pages 351–3521. Any order: face, end.2. two-flute3. two-flute4. inserted tooth5. vernier6. Any order: tilting the spindle head; setting

the work at the specified angle in the vise;using the protractor head of the combina-tion set to position the work.

7. edge finder, wiggler, or centering scope8. dial indicator9. Evaluate individually. Refer to Section 18.3.4.

10. a. Several cutters being used at same timeto machine a job.

11. To prevent it from slipping during machining.12. smallest13. shortest14. Evaluate individually. Refer to Section 18.5.1.15. 0, 45, 1816. A spur gear is a toothed wheel that has teeth

that run straight across the face and are per-pendicular to the sides. The teeth are shapedso contact between the mating gears iscontinually maintained while in operation.

17. A rack is a flat section of metal with teeth cutinto it. The combination of a spur gear and arack converts rotary motion into linearmotion.

18. Evaluate individually.

WORKBOOK ANSWERS,Pages 99–1061. Any order: milling, drilling, boring, reaming.2. If not, a flat surface cannot be machined.3. With a dial indicator and a special holder.4. By wiping the vise jaws and base clean and

inspecting for burrs and ticks.5. Thin paper strips.6. dial indicator7. d. All of the above.8. against9. Evaluate individually. Refer to Section 18.4.

10. It is more efficient because it travels lessdistance while doing the same amount ofwork as a larger cutter.

11. toward12. b. called shell mills13. A machining technique where a pair of cutters

are used to machine both sides of the work atthe same time.

14. Gang milling employs mulitiple cutters tomachine several surfaces in one pass.

15. climb16. Forces the work down against the worktable.17. In slotting, the cut is only made partway

through the work.18. are not19. toward20. eight

Chapter 18 Milling Machine Operations 241

21. To change the angular direction of powerbetween two shafts.

22. b. narrower at the small end than at thelarge end

23. d. All of the above.24. Final inspection is made by running the

mating gears and checking for quietness andshape of the tooth contact.

25. Do = 5.100″D = 5.000″ht = 0.1078″tc = 0.0785″a = 0.050″Dividing head setup = 2/5 turn per toothHole series used on index plate = 18 holesin 45 hole series in index plateGear cutter to be used = No. 2

26. Do = 5.000″D = 4.500″ht = 0.539″tc = 0.392″a = 0.250″Dividing head setup = 5/18 turn per toothHole series used in index plate = 25 holesin 90 hole series in index plateGear cutter to be used = No. 6

27. Do = 1.750″D = 1.500″ht = 0.2696″tc = 0.196″a = 0.125″Dividing head setup = 5/12 turn per toothHole series used in index plate = 15 holesin 36 hole series in index plateGear cutter = No. 8

28. Do = 3.1667″D = 3.0000″ht = 0.1798″tc = 0.1309″a = 0.0833″Dividing head setup = 1 1/9 turns pertoothHole series used in index plate = 9 holes in81 hole series in index plateGear cutter to be used = No. 4





Copyright Goodheart-Willcox Co., Inc. 18-1

Mounting End Mills

Adapter with Setscrew onStraight Shank CutterB&S Taper Mounted

Directly in the Spindle

Adapter Sleeve withTaper Shank Cutter

Spring Collet with StraightShank Cutter

Straight shank cutter

Setscrew

Adapter(R-8 taper)

Taper shank cutter

(B&S taper)

Spring collet(R-8 taper)

Draw-in bar

Spindle

Adapter sleeve(R-8 taper)

Taper shank cutter(tanged shank)


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Straddle Milling

Matchedside milling

cuttersUsing a Spacer Between Cutters

Arbor

Rotation ofcutters

Work travel

Work

Straddle Milling on Flatwork


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• Addendum (a): The distance the toothextends above the pitch circle.

a = or a = or a = 111111

• Circular pitch (p): The distance, measuredon the pitch circle, between similar pointson adjacent teeth.

p = or p = 118

• Clearance (c): The difference between theworking depth and the whole depth of agear tooth. The amount by which the deden-dum on a given gear exceeds the addendumof the mating gear.

c = 11118

• Dedendum (b): The distance the toothextends below the pitch circle.

b = 11118

• Distance between centers of two matinggears (C): This distance may be calculatedby adding the number of teeth of both gearsand dividing one-half that sum by thediametral pitch.

C = 1118

N1 = Number of teeth on first gear.N2 = Number of teeth on second gear.

• Diametral pitch (P): The number of teethper inch of pitch diameter.

P = or P = or P = 1111

• Number of teeth (N): The number of teethon a gear.

N = DP or N =DoP –2 or N =1111

• Outside diameter (Do): Diameter or size ofthe gear blank.

Do = D +2a or Do = + 2 � � or Do =118888

• Pitch circle: An imaginary circle locatedapproximately half the distance from theroots and tops of the gear teeth. It is tangentto the pitch circle of the mating gear.

• Pitch diameter (D): The diameter of thepitch circle.

D = or D = 0.3183pN or D =1111111

• Pressure angle (θ): The angle of pressurebetween contacting teeth of mating gears. Itrepresents the angle at which the forces fromthe teeth of one gear is transmitted to the mat-ing tooth of another gear. Pressure angles of14 1/2°, 20°, and 25° are standard. However,the 20° is replacing the older 14 1/2°.

• Tooth thickness (tc): Thickness of the tooth atthe pitch circle. The dimension used in mea-suring tooth thickness with Vernier geartooth caliper.

tc = 11111

• Whole depth of tooth (ht): Total depth of atooth space, equal to the addendum (a)plus dedendum (b), or the depth to whicheach tooth is cut.

ht = a + b or ht = 11111

• Working depth of tooth (hk): The sum ofthe addendum's of the two mating gears.

hk = a1 + a2



Gear Nomenclature

Do

Dr

c bht

p

tca

hk

D

a = Addendumb = Dedendumc = ClearanceD = Pitch diameterDo = Outside diameter

Dr = Root diameter

hk = Working depth of tooth

ht = Whole depth of tooth

p = Circular pitchtc = Tooth thickness

1P

DN

Do

N + 2

πDN

πpP

0.157P

1.157P

N1 + N2

2 ÷ P

NP

N + 2Do

πP

πDp

NP

N + 2P

DoNN + 2

NP

1p

1.5708P

2.157P


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Name: ______________________________________________Date: _______________ Score: ________

1. _____ mills and _____ mills are the cutters normally usedon a vertical milling machine.

2. The _____ end mill is used when the cutter must be fedinto the work like a drill.

3. Blind holes or closed keyseats are made with a _____ endmill.

4. Face milling cutters over 6″ (150 mm) in diameter areusually of the _____ type.

5. A _____ scale on the spindle head of a vertical millingmachine assures accurate angular settings.

6. List three methods for machining chamfers, bevels, and tapered sections on a vertical millingmachine.____________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

7. An _____ or a _____ can be used to locate the first hole ofa series to be drilled on a vertical milling machine.

8. The most accurate way to align a vise on millingmachine is with a _____.

9. Explain how to center an end mill on round stock for the purpose of machining a keyseat. Usethe paper strip technique. _____________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

10. Gang milling means:a. several cutters being used at same time to machine

a job.b. two or more cutters straddling the job.c. several side cutters being used at same time to machine a job.d. All of the above.e. None of the above.



Milling Machine Operations

(continued)

1. ____________________________

____________________________

2. ____________________________

3. ____________________________

4. ____________________________

5. ____________________________

7. ____________________________

____________________________

8. ____________________________

10. ____________________________

11. Why should a milling cutter be keyed to the arbor? ______________________________________

____________________________________________________________________________________

12. When sawing (slitting) thin stock, the _____ diametercutter that provides adequate clearance should be used.

13. In general, use the _____ arbor possible that permits ade-quate clearance between the arbor support and the work.

14. Describe how to safely remove or mount a milling cutter on an arbor. ______________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

15. How would a dividing head be set up to cut a 100-tooth gear? The dividing head has a 40:1ratio and the index plate has the following series of holes: 33, 37, 41, 45, 49, 53, 57.

______Number of full turns.

______Hole series used.

______Number of holes in sector arm spacing.

16. What is a spur gear? _________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

17. How does a rack differ from a spur gear? _______________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

18. List five precautions to be observed when operating a milling machine. ____________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________


Name: ______________________________________________


12. ____________________________

13. ____________________________


Documents

Milling Machine Operations - NEMESneme-s.org/CTHSS/Machining Fundamentals/MFIM18.pdfMilling Machine Operations LEARNING OBJECTIVES After studying this chapter, students will be able