Mfg Processes Ch 20 and 21

Name three most common machining processes.

turning, drilling, and milling

Which one of the four types of chip would be expected in a turning operation conducted at low cutting speed on a brittle work material: a) continuous, b) continuous with bue, c) discontinuous, or d) serrated?

DISCONTINUOUS

What is the chip thickness ratio?

r = to/tc where r: chip thickness ratio to: original chip thickness/depth of cut tc: final chip thickness after separation

Identify some of the reasons why machining is commercially and technological important.

Applicability to most materials; it can produce a variety of geometries to a part; it can achieve closer tolerances than most other processes; and it can create good surface finishes

Which one of the following stamping dies is the most complicated: a. blanking die, b. combination die, c. compound die, d. edge-bending die, e. progressive die, or f. V-bending die?

Compound die

Name and briefly describe the four types of chips that occur in metal cutting.

Discontinuous—chip is formed into separated segments Continuous—chip does not segment and is formed from a ductile material Continuous with built-up edge (BUE)---same as continuous above, except the friction at the tool-chip interface causes adhesion of a small portion of work material to the tool rake face Serrated---semi-continuous in the sense that they possess a saw-tooth appearance that is produced by a cyclical chip formation of alternating high shear strain followed by low shear strain.

Springback in a sheet metal bending operation is the result of which one of the following: a. elastic modulus of the metal, b. elastic recovery of the metal, c. overbending, and d. overstraining, or e. yield strength of the metal?

Elastic recovery of the metal

Which of the following processes are classified a high-energy rate forming processes: a. electrochemical machining, b. electromagnetic forming, c. electron beam cutting, d. explosive forming, e. Guerin process, f. hydroforming, g. redrawing, and h. shear spinning? (2 best answers)

Electromagnetic and explosive forming

In using the orthogonal cutting model to approximate a turning operation, the chip thickness before the cut t corresponds to which one of the following cutting conditions in turning: a) depth of cut d, b) feed f, or c) speed v?

Feed rate f

Describe in words what the Merchant equation tell us

This equation states that the shear plane angle increases when the rake angle is increased and friction angle is decreased

Sheet metal bending involves which of the following stresses and strains: a compressive, b. shear, and c. tensile? (2 correct answers)

compressive and tensile

The cutting force in a sheet metal blanking operation depends on which mechanical property of the metal: a. compressive strength, b. modulus of elasticity, c. shear strength, d. strain rate, e. tensile strength, or f. yield strength. (1 correct answer)

strain rate

In a sheet metal cutting operation used to produce a flat part with a hole in the center, the part itself is called a blank, and the scrap piece that is cut out to make the hole is called a slug. T or F

true

µ stands for?

µ = coefficient of friction

What does gamma (γ) represent

γ = shear strain

For which one of the following values of chip thickness before the cut to would you expect the specific energy in machining to be the greatest: a) 0.010 inch, b) 0.025 inch, c) 0.12 mm, or d) .50 mm?

.12 mm, smallest chip thickness would have greatest specific energy in machining

Which one of the following metals would usually have the lowest unit horsepower in a machining operation: a) aluminum, b) brass, c) cast iron, or d) steel?

Aluminum would have the lowest unit horsepower in a machining operation

What are the three basic categories of material removal processes?

Conventional machining, abrasive processes, and nontraditional processes

What are the parameters of a machining operation that are included within the scope of cutting conditions?

Cutting conditions include speed, feed, depth of cut, and whether or not a cutting fluid is used.

Which of the following manufacturing processes are classified as material removal processes (two correct answers): a. casting, b. drawing, c. extrusion, d. forging, e. grinding, f. machining, g. molding, h. press working, and i. spinning.

GRINDING and MACHINING are material removal processes

According to the Merchant equation, an increase in rake angle would have which of the following results, all other factors remaining the same (two best answers): a) decrease in friction angle, b) decrease in power requirements, c) decrease in shear plane angle, d) increase in cutting temperature, and e) increase ins hear plane angle?

INCREASE in rake angle would result in a DECREASE in power requirements and increase in shear plane angle. Merchant equation: Phi = 45 + α/2 - β/2 phi: shear plane angle α: rake angle of cutting tool β: friction angle

Which of the following descriptions applies to a V-bending operation as compared to an edge-bending operation: a. costly tooling, b. inexpensive tooling, c. limited to 90 degree bends or less, d. used for high production, e. used for low production, and f. uses a pressure pad to hold down the sheet metal. (2 best answers)

Inexpensive tooling and used for low production

A roughing operation generally involves which one of the following combination of cutting conditions: a). high v, f, and d, b). high v, low f and d, c). low v, high f and d, d). low v, f, and d, where v=cutting speed, f=feed, and d=depth?

LOW cutting speed HIGH feed rate and depth of cut

A lathe is used to perform which one of the following manufacturing operations: a. broaching, b. drilling, c. lapping, d. milling, and e. turning.

Lathes are used to perform TURNING

Which one of the following is the best definition of bend allowance: a. amount by which the die is larger than the punch, b. amount of elastic recovery experienced by the metal after bending, c. safety factor used in calculating bending force, or d. length before bending of the straight sheet metal section to be bent?

Length before bending of the straight sheet metal section to be bent

Which one of the following press types is usually associated with the highest production rates in sheet metal stamping operations: a. adjustable bed, b. open back inclinable, c. press brake, d.. solid gap, or e. straight-sided?

Open back inclinable

What is an orthogonal cutting operation

Orthogonal cutting involves the use of a wedge-shaped tool in which the cutting edge is perpendicular to the direction of speed motion into the work material

Which of the following are characteristics of the orthogonal cutting model (three best answers): a) a circular cutting edge is used, b) a multiple cutting edge tool is used, c) a sing-point tool is used, d) only two dimensions play an active role in the analysis, e) the cutting edge is parallel to the direction of cutting speed, f). the cutting edge is perpendicular to the direction of cutting speed, and g) the two elements of tool geometry are rake and relief angle?

Orthogonal cutting model: Only two dimensions play an active role in the analysis The cutting edge is perpendicular to the direction of cutting speed The two elements of tool geometry are rake and relief angle

With which one of the following geometric forms is the drilling operation most closely associated: a. external cylinder, b. flat plane, c. round hole, d. screw threads, or e. sphere.

ROUND HOLE

Which of the following cutting conditions has the strongest effect on cutting temperature: a) feed or b) speed?

Speed

Identify the four forces that act upon the chip in the orthogonal metal cutting model but cannot be measured directly in an operation

The four forces that act upon the chip are friction force, normal force to friction, shear force, and the normal force to shear force.

How is power required in a cutting operation related to the cutting force?

The power required in a cutting operation is equal to the cutting force multiplied by the cutting speed.

What does the term size effect mean in metal cutting?

The size effect refers to the fact that the specific energy increases as the cross-sectional area of the chip (to x w in orthogonal cutting or f x d in turning) decreases.

Which of the following are variations of sheet metal bending operations: a. coining, b. flanging, c. hemming, d. ironing, e. notching, f. shear spinning, g. trimming, and h. tube bending? (two best answers)

flanging and hemming

The holding force in drawing is most likely to be a. greater than, b. equal to, or c. less than the maximum drawing force?

holding force most likely to be LESS than maximum drawing force

As sheet metal stock hardness increases in a blanking operation, the clearance between punch and die should be a. decreased, b. increased, or c. remain the same?

increased

Most sheet metalworking operations are performed as which one of the following: a. cold working, b. hot working, or c. warming working.

most sheet metalworking operations are performed using COLD WORKING

A circular sheet metal slug produced in a hole punching operation will have the same diameter as a. the die opening or b. the punch?

the die opening