Machining Operations

Question 1

What is an advantage of machining over casting?

Answer 1

Greater precision and accuracy

Question 2

What are the two types of machined parts?

Answer 2

Rotational or non-rotational

Question 3

What two factors of a machine operation determine the part geometry?

Answer 3

(1) the relative motions between the tool and the workpart

(2) the shape of the cutting tool

Question 4

What is turning?

Answer 4

Turning is a machining process in which a single-point tool removes material from the surface of a rotating workpiece. Turning is traditionally carried out on a machine tool called a lathe.

Question 5

Describe the lathe operation facing

Answer 5

The tool is fed radially into the rotating work on one end to create a flat surface on the end.

Question 6

Describe the lathe operation taper turning

Answer 6

Instead of feeding the tool parallel to the axis of rotation of the work, the tool is fed at an angle, thus creating a tapered cylinder or conical shape.

Question 7

Describe the lathe operation contour turning

Answer 7

Instead of feeding the tool along a straight line parallel to the axis of rotation as in turning, the tool follows a contour that is other than straight, thus creating a contoured form in the turned part.

Question 8

Describe the lathe operation form turning

Answer 8

In this operation, sometimes called forming, the tool has a shape that is imparted to the work by plunging the tool radially into the work.

Question 9

Describe the lathe operation chamfering

Answer 9

The cutting edge of the tool is used to cut an angle on the corner of the cylinder, forming what is called a “chamfer”.

Question 10

Describe the lathe operation cutoff

Answer 10

The tool is fed radially into the rotating work at some location along its length to cut off the end of the part. This operation is sometimes referred to as parting.

Question 11

Describe the lathe operation threading

Answer 11

A pointed tool is fed linearly across the outside surface of the rotating workpart in a direction parallel to the axis of rotation at a large effective feed rate, thus creating threads in the cylinder.

Question 12

Describe the lathe operation boring

Answer 12

A single-point tool is fed linearly, parallel to the axis of rotation, on the inside diameter of an existing hole in the part.

Question 13

Describe the lathe operation drilling

Answer 13

Drilling can be performed on a lathe by feeding the drill into the rotating work along its axis. Reaming can be performed in a similar way.

Question 14

Describe the lathe operation knurling

Answer 14

This is not a machining operation because it does not involve cutting of material. Instead, it is a metal forming operation used to produce a regular crosshatched pattern in the work surface.

Question 15

What is the difference between drilling and boring?

Answer 15

Drilling creates a new hole in a workpiece whereas boring enlarges an existing workpiece

Question 16

Describe the drilling operation reaming

Answer 16

Reaming is used to slightly enlarge a hole, to provide a better tolerance on its diameter, and to improve its surface finish. The tool is called a reamer, and it usually has straight flutes.

Question 17

Describe the drilling operation tapping

Answer 17

This operation is performed by a tap and is used to provide internal screw threads on an existing hole.

Question 18

Describe the drilling operation counterboring

Answer 18

Counterboring provides a stepped hole, in which a larger diameter follows a smaller diameter partially into the hole. A counterbored hole is used to seat bolt heads into a hole so the heads do not protrude above the surface.

Question 19

Describe the drilling operation countersinking

Answer 19

This is similar to counterboring, except that the step in the hole is cone shaped for flat head screws and bolts

Question 20

Describe the drilling operation centering

Answer 20

Also called center drilling, this operation drills a starting hole to accurately establish its location for subsequent drilling. The tool is called a center drill.

Question 21

Describe the drilling operation spotfacing

Answer 21

Spot facing is similar to milling. It is used to provide a flat machined surface on the workpart in a localized area.

Question 22

What is milling?

Answer 22

Milling is a machining operation in which a workpart is fed past a rotating cylindrical tool with multiple cutting edges.

Question 23

What are the two basic types of milling?

Answer 23

Peripheral milling

Face milling

Question 24

What are the six types of face milling?

Answer 24

Conventional face milling
Partial face milling
End milling
Profile milling
Pocket milling
Surface contouring