HW4

What is the difference between peripheral milling and face milling?

Peripheral Milling, cutting is accomplished by the peripheral teeth of the milling cutter and the tool axis is parallel to the work surface; Face Milling, cutting is accomplished by the flat face of the cutter whose axis is perpendicular to the work surface

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 lathe. - A live center is mounted in bearings and rotates w/ the work, while a dead center does not rotate - the work rotates about it.

Describe the difference b/w 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

What is the difference between absolute positioning and incremental positioning?

- In absolute positioning, the locations are defined relative to the origin of the axis system. - In incremental positioning, each succeeding location is defined relative to the previous location.

Blind Hole

- does not exit the work; by comparsion, a through hole exits the opposite side of the work part.

Forming when machining work part geometries.

- involves the creation of work geometry due to the shape of the cutting tool, + common examples include form turning and drilling.

tapping Operation

- is normally performed on a drilling machine and produces an internal thread

Threading Operation

- is performed on a turning machine and produces an external thread

What can a mill-turn center do that a conventional turning center cannot do?

- mill-turn cnter has the capacity to position a rotational work part at a specified angular location, permitting milling or drilling to be performed at a location on the periphery of the part

What is manual data input in NC part programming?

- refers to a method of programming in which the machine tool operator accomplishes the programming of the NC machine using a menu-driven procedure. Programming is simplified to minimize the amount of training required by the operator.

Generating when machining work part geometries.

- refers to the creation of work geometry due to the feed trajectory of the cutting tool; + examples include straight turning, taper turning, and profile turning.

The mechanisms by which cutting tools wear during machining

1) abrasion 2) adhesion 3) diffusion 4) plastic deformation of the cutting edge.

Tool life criterias used in production machining operations?

1) complete failure of the tool 2) visual observation of flank or crater wear, 3) fingernail test to feel flank wear 4) sound of the tool 5) chip disposal problems 6) degradation if finish, 7) power increasem 8) work-piece count, 9) length of cutting time for the tool

the principal alloying ingredients in high-speed steel

1) either tungsten or a combination of tungsten and molybdenum 2) chromium 3) vanadium 4) carbon = some grades of HSS also contain cobalt

3 modes of tool failure in machining

1) fracture failure 2) temperature failure 3) gradual wear

Three desirable properties of a cutting-tool material

1) toughness to resist fracture failure 2) hot hardness to resist temperature failure 3) wear resistance to prolong the life of the tool during gradual wear

What is the difference between point-to-point and continuous path in a motion control system?

In point-to-point, the motion is from one location in space to the next with no regard for the path taken between starting and final locations. In continuous path, the trajectory of the movement is controlled.

Common compounds that form the thin coating on the surface of coated carbide inserts

TiN, TiC, and Al2O3

How does a turret lathe differ from an engine lathe?

a turret lathe has a toolholding turret in place of a tailstock; the tool in the turret can be brought to work to perform multiple cutting operations on the work w/o the need to change tools as in operating a conventional engine lathe.

Prismatic parts

are block-shaped or flat and are generally produced on a milling machine, sharper, or planner.

Rotational parts

are cylindrical or disk-shaped and are machined on a turning machine (e.g., a lathe)

why are ceramic cutting tools generally designed with negative rake angles?

ceramics possess low shear and tensilfe strength but good compressive strength. During cutting, this combination of properties is best exploited by giving the tool a negative rake angle to load the tool in compression

In addition to cutting speed, other cutting variables included in the expanded version of the Taylor tool life equation

feed depth of cut material hardness

The physical interpretation of the parameter C in the Taylor tool life equation?

the cutting speed corresponding to a one-min tool life. C is the speed-axis intercept on the log-log of the tool life data.

Two principal aspects of cutting-tool technology?

tool material and tool geometry

Pocket Milling

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

two principle locations on a cutting tool where tool wear occurs?

wear occurs on the top face of cutting tool as crater wear and on the side or flank of the tool, called flank wear.