Ch 21

Sawing

A basic machining process in which chips are produced by a succession of small cutting edges, or teeth, arranged in a narrow line on a saw "blade".

Machine Tool

A stationary, power-driven machine used to cut, shape, or form materials such as metal and wood.

Built Up Edge

A variation of continuous chip, often encountered in machining ductile materials.

Shear force

Aka flow stress-is a material constant.

Shear velocity

Can be found using sophisticated electronics and slow-motion playback.

Cutting Velocity

Can cause the process-induced variation in the cutting force.

Regenerative chatter

Caused by a phase shift between overlapping cutting paths ;a self-excited vibration that is caused by the closed -loop displacement response of the machining process

Shear strain

Depends only on the rake angle (alpha) ; expressed as cosine of alpha divided by one plus the sine of alpha.

Work piece

Held in work holding devices.

Work holding device

Holds work pieces.

Feed

Is the amount of material removed per revolution per per pass of the tool over the workpiece.

Grinding

One of the 7 basic chip formation processes. (Discussed in chapters 23-27).

Drilling

One of the 7 basic chip formation processes. A rotational multiple-edge tool process.

Broaching

One of the seven basic machining processes in chip formation. Broach, cutting tool moves into work, and work stationary are the machine areas.

Speed

Primary cutting motion, which relates the velocity of the cutting tool relative to the work piece.

Stability lobe diagram

Relates the total width of cut that can be machined to the rotational speed of the tool with a specified number of cutting edges.

Back Rake Angle

The angle that the tool makes with respect to a vertical from the workpiece.

Chip Velocity

The chip has a velocity V_c. (NOTE: look at figure 21-17 page 498)

Depth of Cut

The distance the tool is plunged into the surface.

Vibration

The mechanism by which a process dissipates energy.

Chatter

The most common metal cutting example due to the regeneration of surface waving. Part of self-excited vibration in machining.

Shear angles

The onset of the shear process takes place along the lower boundary of the shear zone defined by the shear angle (phi)

Self-excited vibration

The periodic response of the system to a constant input

Milling

The process of ____ requires two figures because it takes different forms depending upon the selection of the machine tool and the cutting tool; a multiple tooth process, has two feeds; has replaced shaping and planning

Turning

The process of machining external cylindrical and conical surfaces.

Metal Cutting

The process of removing unwanted material from a metal workpiece in the form of chips (often called metal removal).

Dynamics

The product of static stiffening and dampening.

Shaping

The work piece is fed at right angles to the cutting motion between successive strokes of the tool

Oblique machining

Three-dimensional geometry; the cutting edge and the cutting motion are not perpendicular to each other

Orthogonal machining

Two dimensional geometry; done to test machining mechanics and theory; the cutting velocity vector and the cutting edges are perpendicular.

Cutting Stiffness

Used interchangeably with the term specific energy U. A material property related to shear flow stress, hardness and work hardening and is often described in a relative sense of the machinability of materials.

Chip Ratio

Used to compute the shear angle. Defined as t/t_c.

Cutting Tool

Used to machine the workpiece and is the most critical component.

Specific horsepower

Values found experimentally using orthogonal machining

Friction Force

What the resultant R is composed of along with the normal force N acting on the tool/chip interface contact area.

Boring

Where a reduced lead angle or a less round (and smaller nose radius compared to DOC) inserts maintains more axial (stiffer tool direction) orientation of Y, leading to greater stability.