Chapter 21

What is meant by the designation 30 cm x 90 cm (12 in x 36 in) lathe?

A 30 cm x 90 cm (12 in x 36 in) lathe has a 30 cm (12 in) swing (maximum work diameter that can be accommodated) and a 90 cm (36 in) distance between centers (indicating the maximum work length that can be held between centers).

What is a blind hole?

A blind hole does not exit the work; by comparison, a through hole exits the opposite side of the work part.

What is the difference between a live center and a dead center, when these terms are used in the context of workholding in a lathe?

A center holds the workpiece at the tailstock end of the late. A live center is mounted in bearing and rotates with the work, while a dead center does not rotate - the work rotates about it.

What is a machining center?

A machining center is a CNC machine tool capable of performing multiple types of cutting operations involving rotating spindles (i.e. milling, drilling) the machine is typically equipped with automatic tool-changing, pallet shuttles to speed work part changing, and automatic work part positioning.

What is the difference between a machining center and a turning center?

A machining center is generally confined to rotating spindle operations; while a turning center performs turning type operations, generally with single-point tools.

What is the distinguishing feature of a radial drill press?

A radial drill has a long radial arm along which the drill head

What is the distinguishing feature of a radial drill press?

A radial drill has a long radial arm along which the drill head can be positioned to allow the drilling of large work parts. The radial arm can also be swiveled about the column to drill parts on either side of the worktable.

How does a boring operation differ from a turning operation?

Boring produces an internal cylindrical shape from an existing hole, while turning produces an external cylindrical shape

What is the difference between threading and tapping?

A threading operation is performed on a turning machine and produces an external thread, while tapping is normally performed on a drilling machine and produces an internal thread.

How does a turret lathe differ from an engine lathe?

A turret lathe has a tool-holding turret in place of a tailstock; the tools in the turret can be indexed to perform a sequence of different cutting operations on the work without the need to change tools as in operating a convential engine lathe.

Distinguish between generating a forming when machining part geometries.

Generating refers to creating part geometry using the feed trajectory of the cutting tool; examples includes straight turning, taper turning, and profile milling. Forming involves creating part geometry using the shape of the cutting tool; common examples include form turning an drilling.

What is the difference between peripheral milling and face milling?

In peripheral milling, the axis of the tool is parallel to the surface being machined, and the operation is performed by cutting edges on the outside periphery of the cutter. In face milling, the axis of the cutter is perpendicular to the surface being milled, and machining is performed by cutting edges on both the end and outside periphery of the cutter.

Describe the difference between up milling and down milling.

In up milling, the cutter speed direction is opposite the feed direction; in down milling, the direction of cutter rotation is the same as the feed direction.

Name the various ways in which a work part can be held in a lathe.

Methods of holding the work in a lathe include: (1) between centers, (2) chuck, (3) collet, and (4) face plate.

What is pocket milling?

Pocket milling uses an end milling cutter to machine a shallow cavity (a "pocket") in to a flat work part.

Describe profile milling

Profile milling generally involves the milling of the outside periphery of a flat part.

What are the geometric differences between rotational parts and prismatic parts in machining?

Rotational parts are cylindrical or disk-shaped and are machines on a turning machine; prismatic parts are block-shaped or flat and are generally produced on a milling machine, shaper, or planer

How does a universal milling machine differ from a conventional knee-and-column machine?

The universal milling machine has a worktable that can be rotated about a vertical axis to present that part at any specified angle to the cutter spindle.

Describe the turning process.

Turning is a machining process in which a single-point tool removed material from the surface of a rotating cylindrical workpiece, the tool being fed in a direction parallel to the axis of work rotation.