Chapter 17 and 18 Processes

Gear cutters are made with _____ different forms for each diametrical pitch.

8

In the context of end mills, the term hand is used to describe _____. A. cutter rotation and helix of the flutes B. the type of shank on the cutter C. manual milling machines D. the number of flutes on the cutter

A

Rapid traverse feed _____. A. permits work to be positioned at the fastest rate indicated on the feed chart B. should only be activated while the cutter is positioned in a cut C. allows fast power movement only when work is parallel with the periphery of the cutter D. is a manual form of milling machine control

A

The ideal milling cutter should have _____. A. edge toughness B. an HSS cutting edge C. low abrasion resistance D. high softness and ductility

A

Arbor

A device used to hold and drive cutters on metalworking and other industrial machines

Machine Backlash

A hesitation or failure to begin moving immediately when an axis is reversed. It is caused by the clearance between the drive screw and the mating nuts that move the axes and increases with wear over time.

Peripheral Milling

A milling operation in which the surface being machined is parallel with the periphery of the cutter. Also called edge milling

Conventional Milling

A milling operation in which the work is fed into the rotation of the cutter. Also called up-milling

Climb Milling

A milling technique in which the teeth of a ccutting tool advance into the work in the same direction as the feed. Also called down-milling

Bevel Gear

A toothed wheel used to change the angular direction of power between shafts. The teeth may be either straight or curved.

Side Milling Cutter

A type of milling cutter with cutting edges located on the circumference and on one or both sides of the cutter. They are made in solid form or with inserted teeth.

Horizontal Milling Machine

A type of milling machine in which the cutter is fitted onto an arbor mounted in the machine on an axis parallel with the worktable. Multiple cutters may be mounted on the arbor for some operations.

Vertical Milling Machine

A type of milling machine in which the cutter is normally perpendicular to the worktable. On many vertical milling machines, the spindle can be tilted to perform angular cutting operations.

Fixed-Bed Milling Machine

A type of milling machine that has a very rigid worktable construction and support. The worktable moves only in a longitudinal direction and can very in length. Vertical and cross movements are obtained by moving the cutter head.

Spur Gear

A wheel with teeth that run straight across the gear face, perpendicular to the sides

Slitting

An operation in which a thin cutter or rotary knife is used to cut sheet metal into narrow strips

Cemented tungsten carbides can be operated at speeds _____ than conventional HSS cutting tools. A. much slower B. 3 to 10 times faster C. 10 to 14 times faster D. up to 20 times faster

B

Climb milling should not be performed on machines that _____. A. allow significant play in the table B. are not in top condition C. are fitted with an antibacklash device D. were manufactured later than the year 2000

B

Face mills smaller than 6" are _____ and are heldon a style C arbor. A. held on a long arbor B. called shell end mills C. the inserted tooth type D. mounted directly on the spindle nose

B

The Woodruff key seat cutter is used to mill _____. A. the bottom of t-slots B. semicircular keyseats C. dovetail ways D. through holes

B

The tooth space at the pitch diameter of bevel gears is _____. A. the same at the small end as at the large end B. narrower at the small end than at the large end C. narrower at the large end than at the small end D. four times greater at the small end than at the large end

B

Holes may be located to very close tolerances for drilling, reaming, or boring on a vertical milling machine using any of the following items except a _____. A. wiggler B. edge finder C. combination set D. centering scope

C

The milling machine is a versatile machine that can do all of the following except: A. drill, bore, and cut gears B. machine irregularly shaped surfaces C. ream a highly accurate hole with a fine finish D. machine threads, gears, and spirals

C

What method is used to mill high-quality threads in holes that are at least 3/8" in diameter?

CNC machining centers with helical interpolation

Cutting speeds and feeds on a milling machine may be changed by any of the following methods except _____. A. by shifting v-belts or by adjusting variable speed pulley B. electronically C. by using quick change gears D. pneumatically

D

High-speed stell milling cutters can be improved by the application of any of the following except _____. A. coatings such as chromium or tungsten B. lubricating treatments C. surface hardening treatments D. oxidation treatments

D

The rotary table can be used to cut any of the following except _____. A. irregular-shaped objects B. segments of circles C. circular slots three-dimensional shapes

D

Which of the following is not true about formed milling cutters? A. they include corner rounding cutters B. they include concave and convex cutters C. they can be used to duplicate a contour D. they can mill the bottoms of t-slots

D

Cutting Speed

In reference to milling machines, the distance, measured in feet or meters, that a point on the cutter's circumference will move in one minute. In reference to lathes, the distance the work moves past the cutting tool, expressed in feet per minute or meters per minute. Measuring is done on the circumference of the work. In reference to drilling machines, it is the speed at which the cutting tool rotates

Face Milling

Machining large, flat surfaces parallel to the cutter face

Column-and-Knee Milling Machine

Milling machine that consists of a column that supports and guides the knee in vertical movement and a knee that supports the mechanism for obtaining table movements. These movements are transverse and longitudinal.

Slotting

Similar to slitting, except that the cut is made only part way through the work. The slot in a screw head is an example of slotting

Addendum

The distance a gear tooth extends above or outside the pitch circle

Dedendum

The distance a gear tooth extends below the pitch circle

Diametral Pitch

The number of gear teeth per inch of pitch diameter

Feed

The rate at which work moves into the cutter or the cutter moves into the work

List four purposes for cutting fluids.

They carry away heat generated during machining They act as a lubricant Prevent the chips from sticking to or fusing with the cutter teeth Flush away chips

Straddle Milling

Using milling cutters in pairs to machine opposite sides of a piece simultaneously

Gang Milling

Using two or more milling cutters to machine several surfaces at one time

What is a fly cutter?

a single-point cutting tool used as a face mill

Metal slitting saw cutter

a thin milling cutter designed to machine narrow slots and for cutoff operations

When milling an internal slow that is wider than the cutter diameter, it is important that the direction of feed, in relation to cutter rotation, be observed, Feed direction is normally _____ cutter rotation.

against

Pitch Circle

an imaginary circle located approximately half the distance from roots and tops of gear teeth. It is tangent to the pitch circle of the mating gear

Inch-based gears and metric-based gears -____ interchangeable.

are not

When slitting thiin metal sections, best results can be obtained if the cutter is mounted for _____ milling.

climb

Spacing _____ allow two or more cutters to be positioned on the arbor for gang and saddle milling.

collars

On a fixed-bed milling machine, vertical and cross movements are obtained by moving the _____.

cutter head

Explain straddle milling.

cutters are used in pairs to machine opposite sides of a piece at the same time

When extreme accuracy is required, the vise jaws must be aligned with a _____.

dial indicator

A _____ can be used to measure the circumference of circular work into equally spaced units.

dividing head

_____ fit into slots on the arbor, collet, or collet holder to provide nonslip drive.

drive keys

In what units is feed expressed?

feed per tooth per revolution

Cutting speed is expressed in _____ per minute.

feet

Staggered-tooth side cutter

has alternate right-hand and left-hand helical teeth

Side milling cutter

has cutting teeth on the circumference and on both sides

Slab mill cutter

has helical teeth designed to cut with a shearing action

Why must the spindle of a vertical milling machine be at an exact right angle to the worktable?

if it is not perpendicular, it is not possible to machine a flat surface

How does gang milling differ from straddle milling?

in gang milling, several cutters are mounted on an arbor to machine several surfaces in a single pass, it is used when many identical pieces must be made

How does slotting differ from slitting?

in slotting the cut is made only partway through the work

When indexing, it _____ necessary to count holes each time the work is repositioned after a tooth has been cut.

is not

Why is the term high-velocity machining preferred over high-speed machining?

it implies more than high spindle speeds

List four operations the vertical milling machine is capable of performing.

milling, drilling, boring, and reaming

Plain milling cutter

mounts on an arbor and has cutting teeth only on its circumference

A multiflute end mill is recommended for conventional milling when _____ is not necessary.

plunge cutting

How is the final inspection made after bevel gears are finished?

running mating gears and checking for quietness and shape of the tooth contact

In general, use the _____ arbor possible that permits adequate clearance between the arbor support and the work.

shortest

Shell end mill have teeth simmilar to the multiflute end mills but are mounted on a _____ arbor.

stub

Circular Pitch

the distance measured on the pitch circle, between similar points on adjacent teeth

Define the term cutting speed.

the distance, measured in feet or meters, that a point on the cutter's circumference moces in one minute

Define the term feed.

the rate at which work moves into the cutter

How do milling machines found in industry compare with those in training programs?

they operate on the same basic principles

_____ can be used to check whether the work is firmly seated in the vise.

thin paper strips

When machining gears, cutting is done _____ the dividing head.

toward

When using a helical slab mill, mount it so the cutting pressure forces it _____ the column.

toward

_____ end mills can be fed into the work like a drill.

two-flute

When are bevel gears used?

used to change the angular direction of power between shafts

How should a vise be prepared for mounting to the worktable and holding work?

wipe the vise base and worktable clean

What is the most accurate way to check for milling head perpendicularity?

with the use of a dial indicator