Machine Tools Test 2

All questions + answers from the Turning Unit EXCLUDING Unit 4. I felt as though that chapter was less relevant to what we did in class

List the four main parts of the engine lathe.

List the four main parts of the engine lathe.

Headstock, bed, carriage, tailstock

What are the two main purposes of the lathe spindle?

holds and rotates work during machining

What part of the lathe is used to set the feed rate of the cutting tool?

quick-change gear box

What are the two main components of the carriage?

the saddle and the apron

What function does the compound rest serve?

provides and allows angular tool movement

What is the purpose of the leadscrew of a lathe?

transmits motion to the carriage for thread-cutting operations

What two functions can the lathe tailstock perform?

secures work holding accessories and holds cutting tools for performing hole-making operations

The standard taper in most lathe tailstocks is the _____ taper.

Morse

Define the swing and the bed length of a lathe.

The swing is the biggest diameter workpiece that can be mounted in the spindle without touching ways. Bed length is measured from the headstock to the end of the bed.

What is the special name for the type of jaw-type chuck that has a mechanism to move the jaws simultaneously?

universal chucks

The most common variation of the jaw-type chuck has how many jaws?

three

Name two material shapes that can be properly held in a three-jaw chuck.

round shape or have a number of flat sides divisible by three

List two advantages of using a self-centering chuck.

The jaws advance and retract simultaneously, making them quicker and easier to use

The workpiece is automatically centered, making something like drilling a whole through the center of a workpiece easier (?)

Name two material shapes that can be properly held in a four-jaw chuck.

when the necessary part accuracy cannot be achieved with a three-jaw chuck, or when the number of sides of the workpiece is divisible by four

List three benefits of holding a workpiece between centers.

1) The workpiece can easily be removed, flipped, and replaced with a high degree of repeatability and accuracy.
2) A diameter to be machined end-to-end will maintain concentricity and have very little runout.
3) It provides even support on both ends of a workpiece and makes for a more rigid setup with less deflection.

List three potential advantages of using an independent chuck for a work holding situation.

1) Workpiece can be centered more accurately by manual adjustment.
2) Non-symmetrical shapes can be clamped in the chuck.
3) The workpiece can be purposefully offset within the chuck.

List three characteristics of a workpiece that would make a mandrel the ideal workholding device.

1) The workpiece features a straight hole or bore all the way through it's center.
2) It is desired that the outside diameter be concentric to the bore.
3) It is desirable to machine the entire outside surface of the part without removing it from the chuck.

What type of mandrel would be ideal for gripping a workpiece on an accurately machined, but odd-sized hole?

expansion

Name the type of tailstock center that would be selected to support a workpiece for most lathe operations.

live center

What two auxiliary devices can be used to stabilize long, slender workpieces for turning operations?

steady rest and follower rest

Explain the differences between the two auxiliary devices in the previous question.

Steady: clamps directly to the lathe’s ways and acts as a brace to surround and support the workpiece

Follower: attached to the carriage and moves along the length of the workpiece with the tool during machining

Name the device that is used to transmit the spindle power to the workpiece when held between centers.

drive dog (AKA lathe dog)

Which two tool posts are the most efficient if several tools are to be used?

rocker-type and quick-change

Which device may be used for either tool holding or workholding?

tailstock

If a 0.050” depth of cut is taken on the diameter of a workpiece by how much will the diameter be reduced?

When cutting a diameter, the diameter is reduced by two times the depth of cut. This means that the diameter is reduced by 0.100” (0.050 × 2 = 0.100).

A lathe cross slide uses a diameter-reading micrometer collar. If the cross slide is advanced by 0.150”, what depth of cut would result?

0.150/2 = 0.075” (pg. 388)

In what units are feed rates measured for lathe operations?

RPM (rotations per minute)

Are deeper cuts used for roughing or finishing operations?

roughing

Calculate spindle RPM and machining time for cutting a 1.5” diameter 4” long at 225 SFPM using a feed rate of 0.004”.

*Look at page 389 and 390 for formulas :)

3.82 × 225 = 859.5 / 1.5 = 573 RPM
4 / (573 × 0.004) = ~1.7452007

~1.7452007 × 10 = 17.452007 / 60 = ~0.29 hour

List three safety precautions related to clothing that should be observed during lathe operation.

1) Wear NSI Z89 rated safety glasses

2) Do not wear any loose clothing or jewelry

3) Wear short sleeves or roll-up long sleeves

What two materials are most commonly used for lathe cutting tools?

High-speed steel or brazed carbide

What feature of a lathe cutting tool has a direct effect on surface finish?

tool nose radius (?)

Is a left-hand or right-hand tool normally used for facing?

left

What part of the lathe is used to feed the tool during facing?

cross-slide

When facing, why should the tool not be fed past the center of the workpiece?

it can cause excessive tool wear and can break the tip

Should a left-hand or right-hand tool be used when turning toward the headstock?

right

When and how should chips be removed from the work and cutting tool?

Using a brush, pliers, or chip hook, and only when the spindle has come to a complete stop.

What are two reasons for center drilling on the lathe?

1. Create a 60-degree bearing surface for lathe centers.
2. Create a starting point that will prevent a twist drill from walking off center when it begins to cut.

When drilling and reaming on the lathe, how are the tools usually fed into the workpiece?

They both use the quill and handwheel graduations to monitor depth.

How can hole depth be controlled during drilling operations?

with the graduations on the quill and the hand wheel

What are two reasons boring may be selected to produce a hole instead of drilling and reaming?

1. Any desired hole size can be machined.
2. Produces large-diameter holes that are beyond the range of drills and reamers.

Why must extra care be taken when performing boring operations?

less rigid than other setups, so spindle speeds need to be reduced to eliminate vibration and chatter

How can a tap be aligned when threading a hole on the lathe?

A spring loaded tap center can be mounted in a tailstock drill chuck to keep the tap aligned with the hole.

Briefly define form cutting.

produces contoured surfaces using specially shaped tools to achieve the desired form

How do grooving and cutoff speeds compare to turning speeds?

Greatly reduced, 1/3-1/4 of normal speeds

How can tool binding be overcome when cutting deep grooves or cutting off large diameters?

By cutting to a partial depth and then widening the groove to provide clearance

List two basic knurl patterns.

Diamond and straight-line

How is knurling different from other lathe operations?

applies pressure to raise the surface and does not generally remove material

List and briefly describe the two different types of knurling tools.

Bump-type tools which apply pressure asymmetrically, and clamp-type tools which apply pressure on opposing sides of a part

Briefly define a taper.

a constant change in diameter of a cylindrical part

What is the difference between an included angle and a centerline angle?

included angle: the measure of the entire angle from one side of the tapered cylinder to the other side

centerline angle: measured from one side of the tapered cylinder to the centerline of the cylinder

What does TPI stand for in relation to tapers?

Taper per inch