ACTUALLY STUDY THIS IME 143 MIDTERM

A Ø20' 4-Flute Carbide insert face mill is being used to face mill a flat surface on the top of a Ø1.0' 4130 steel workpiece held in a collet vise. If the surface speed is 400 ft/min and the chip load is .002 in/tooth, calculate the table feed for the CNC milling operation.

6.4

Machining processes remove material in the form of

chips

All machining processes are performed on

machine tools

Four elements required to perform machining processes

workpiece, cutting tool, machine tool, production personnel

Common cutting processes

turning, milling, drilling, sawing, broaching

Three common machining variables

depth of cut, feed rate, surface speed

Depth of cut

how deep the tool cuts into the material

Depth of cut on a lathe

how deep the cutting tool cuts into the workpiece radially; the diameter is reduced by twice the depth of cut

Why is diameter reduced by twice the depth of cut?

because depth of cut is measured on the radius, and diameter is twice the radius

Surface speed

the linear velocity between the cutting tool and the workpiece

Surface speed units

ft/min

Chip load

the thickness of material removed by each cutting edge or tooth on a cutter

Chip load units

in/tooth

Lathe feed

distance the tool moves in one revolution of the workpiece

Feed rate units on turning

in/rev

Milling table feed

distance the table or cutter moves in one minute

Feed rate units on milling

in/min

Table feed formula

F = N x f x n

Milling parameter symbols

F = table feed in in/min, N = spindle speed in rpm, f = chip load in in/tooth, n = number of teeth, D = cutter diameter, V = surface speed

RPM milling formula

N = 4V / D

Lathe RPM formula

RPM = 12V / (pi x D)

Cutting fluids are used during machining processes as they __________ the tool and workpiece.

cool and lubricate

Cutting fluids reduce

friction

Cutting fluids also

cool the tool and workpiece

Four main types of cutting fluids

oils, emulsions, gasses, pastes

In machining, which cutting variable has the greatest effect on cutting temperature?

surface speed

In machining during chip formation the tool is forced into the workpiece and the chip is formed by

shear deformation

What stress makes chips

shear stress

Accuracy

the degree to which the measured value agrees with the true value of the quantity of interest

Precision

the degree of repeatability in the measurement process

Difference between accuracy and precision

accuracy is closeness to the true value; precision is repeatability

The rule of X states the measurement devices used to inspect a part should be X times more precise than the specified tolerance. What is X?

10

Surface speed ranking of cutting tool materials

carbide runs fastest, then HSS, then carbon steel

The cutting tool material that has the highest cutting speed value when cutting steel is

carbide

High carbon steel cutting tools

less expensive and commonly used for drills, taps, and reamers

High speed steel HSS

retains hardness up to about 1100 F and can be reground

Carbide

retains very high hardness up to about 1400 F and allows very fast cutting speeds

Four common cutting tool shape features

rake angles, lead angles, corner radius, clearance angles

Rake angle

the inclination of the tool face that helps control chip flow and tool sharpness

Lead angle

the angle between the cutting edge of the tool and the workpiece

Corner radius or nose radius

strengthens the cutting edge, improves finish, and influences tool life

Clearance angle or relief angle

prevents the cutter or tool from rubbing on the workpiece

The function of the nose radius on a lathe's single point cutting tool is to

control surface finish

On a lathe, the __________ is supported by bearings which provide the axis of revolution for the workpiece.

spindle

On a lathe, the __________ provides tool motion in the radial direction.

cross slide

On a manual lathe, drilling is accomplished by use of the

tailstock

Turning

the workpiece rotates against a stationary single point cutting tool to machine cylindrical parts

Facing

produces a flat surface at the end of the part perpendicular to its axis

Difference between facing and turning

facing changes length and makes a flat end surface; turning changes diameter

Machining a cylindrical outside diameter on a workpiece using a lathe requires a

turning tool

Workpiece on a turning center

rotates while the tool is stationary

Compound slide

used for angled tool motion and fine adjustments on a lathe

Cross slide motion per revolution

0.125 inch motion or DOC per revolution and 0.250 inch off diameter per revolution

Compound slide motion per revolution

0.100 inch motion or DOC per revolution and 0.200 inch off diameter per revolution

Difference between compound slide and cross slide

the cross slide moves straight in and out toward the center of the part, while the compound slide moves at an angle and is used for angled cuts and fine adjustments

Milling

a rotating multi-tooth cutter removes material while moving relative to the workpiece

Which machining process involves using a rotating multiple tooth cutter to remove material by feeding a workpiece past it?

milling

Basic CNC milling machines have

3 axes of movement

A traditional CNC machining center has _____ linear axes of motion based off the Cartesian coordinate system.

3

On a vertical mill the table is

the XY plane

On a vertical mill the spindle axis is

the Z axis

Right hand rule

used to determine positive X, Y, and Z axis directions on machine tools

On the Haas CNC mill, the spindle's axis of rotation is oriented in the

z axis

Conventional milling

the cutter rotates against the feed direction and the chip starts thin and gets thicker

Climb milling

max chip thickness occurs when the tooth first contacts the work and the cutter tends to pull the work into the cutter and hold it against the machine table

Difference between climb and conventional milling

climb milling starts with maximum chip thickness and pulls the work into the cutter; conventional milling starts thin and pushes the work

Which milling direction do we use on the CNC?

climb milling

_____ milling is machining of a flat surface which is at a right angle to the axis of the rotating cutter.

Face

Face milling

machining of a flat surface normal or 90 degrees to the axis of the rotating cutter

Peripheral milling

the axis of cutter rotation is parallel to the workpiece surface

Difference between face milling and peripheral milling

face milling has cutter axis perpendicular to the surface; peripheral milling has cutter axis parallel to the surface

Drilling

the most common machining process used to create cylindrical holes with a twist drill

Twist drills are commonly held in

drill chucks

Four drill size systems

metric, fractional, letter, number

Center drill

short rigid drill used to create a conical starter hole so the drill starts accurately and does not walk

Spot drill

used to start a hole accurately so the twist drill begins in the correct location

Spot drill vs center drill

both start a hole accurately, but a center drill is stronger and can also be used to make lathe center holes

The purpose for center drilling or spot drilling a workpiece is to

locate an accurate starting point for a twist drill

Boring

an operation in which a preexisting hole is enlarged to a precise value using a single point cutting tool

Reaming

slightly enlarges a preexisting hole to a tight tolerance using a multi-edge cutting tool

Difference between reaming and boring

reaming slightly enlarges and finishes a hole with a multi-edge tool, while boring enlarges a hole with a single point cutting tool

Which cutting tool holds a tighter tolerance for making a round hole to the exact size?

reamer

Boring can be performed on

a mill or a lathe

Threads are used for

fasteners and for translating machine parts against heavy loads

External thread class

A

Internal thread class

B

Die

used to cut external threads

Tap

used to cut internal threads

Difference between die and tap

die cuts external threads; tap cuts internal threads

A or B thread callout

A = external thread, B = internal thread

Thread tapping

cutting an internal thread with a multiple-point tool called a tap

Dies are usually held in

a stock for hand rotation

Before tapping you must

drill a hole slightly larger than the minor diameter

Common tap types

taper tap, plug tap, bottoming tap, spiral flute tap

Manufacturing engineers create __________ to establish one single part's manufacturing operation steps in order.

routings

Manufacturing engineers create __________ to instruct the manufacturing technicians on how to properly perform one single manufacturing sequence in the shop.

operation sheets

Production planning

the technique of foreseeing every step in a long series of operations so each step is done at the right time, in the right place, and with maximum efficiency

Shop flow planning and control includes

planning, routing, scheduling, dispatching, and follow up

Routing

establishes the manufacturing operations, their path, and the most efficient sequence

Main aim of routing

determine the best and cheapest sequence of operations and ensure it is followed