CH 19 Multiple Choice Q's

19.10 An increase in cobalt content has which of the following effects on WC-Co cemented carbides: (a) decreases hardness, (b) decreases transverse rupture strength, (c) increases hardness, (d) increases toughness, and (e) increases wear resistance?

- decreases hardness - increases toughness

19.1 Of the three possible modes by which a cutting tool can fail during a machining operation, which one is most preferable: (a) fracture failure, (b) gradual wear, or (c) temperature failure?

gradual wear

19.11 Steel-cutting grades of cemented carbide are typically characterized by which of the following ingredients: (a) Co, (b) CrC, (c) Mo, (d) Ni, (e) TiC, and (f) WC?

Co, TiC, WC

19.7 As an alloying ingredient in high-speed steel, chromium serves which of the following functions: (a) depth hardenability during heat treatment, (b) forms hard carbides to resist abrasion, (c) improves strength and hardness, (d) increases corrosion resistance, (e) increases hot hardness, and (f) increases toughness?

- depth hardenability during heat treatment - forms hard carbides to resist abrasion - increases corrosion resistance

19.6 As an alloying ingredient in high-speed steel, tungsten serves which of the following functions: (a) depth hardenability during heat treatment, (b) forms hard carbides to resist abrasion, (c) improves strength and hardness, (d) increases corrosion resistance, (e) increases hot hardness, and (f) increases toughness?

- increases hot hardness - forms hard carbides to resist abrasion

19.18 Chip breakers are frequently used with single-point tools. They work by forcing the chips to curl more tightly than they would naturally be inclined to curl, thus causing them to fracture: (a) true or (b) false?

True

19.8 Cast cobalt alloys typically contain which of the following as their main ingredients (three best answers): (a) aluminum, (b) cobalt, (c) chromium, (d) iron, (e) nickel, (f) steel, and (g) tungsten?

cobalt, chromium, tungsten

19.2 Which of the following are the two main types of gradual wear on a cutting tool: (a) clearance wear, (b) crater wear, (c) flank wear, (d) nose wear, and (e) notch wear?

crater wear, flank wear

19.14 Which one of the following materials has the highest hardness: (a) aluminum oxide, (b) cubic boron nitride, (c) high-speed steel, (d) titanium carbide, or (e) tungsten carbide?

cubic boron nitride

19.4 Of the following cutting conditions, which one has the greatest effect on tool wear: (a) cutting speed, (b) depth of cut, or (c) feed?

cutting speed

19.3 The basic Taylor tool life equation defines the relationship between which two of the following variables: (a) cutting speed, (b) depth of cut, (c) feed, (d) feed rate, (e) tool life, and (f) work material hardness?

cutting speed and tool life

19.20 Which of the following are the two main functions of a cutting fluid in machining: (a) improve surface finish on the workpiece, (b) reduce forces and power, (c) reduce friction at the tool-chip interface, (d) remove heat from the process, and (e) wash away chips?

- reduce friction at the tool-chip interface - remove heat from the process

19.9 Which of the following is not a common ingredient in cemented carbide cutting tools: (a) Al2O3, (b) Co, (c) CrC, (d) TiC, and (e) WC?

Al_2O_3, CrC

19.12 If you had to select a cemented carbide for an application involving finish turning of steel, which C-grade would you select (one best answer): (a) C1, (b) C3, (c) C5, or (d) C7?

C7

19.15 Most ceramic cutting tools are fabricated from which one of the following materials: (a) aluminum oxide, (b) cubic boron nitride, (c) titanium carbide, (d) titanium nitride, or (e) tungsten carbide?

aluminum oxide

19.13 Which of the following processes are used to provide very thin coatings on the surface of coated carbide inserts: (a) chemical vapor deposition, (b) electroplating, (c) physical vapor deposition, (d) pressing and sintering, and (e) spray painting?

chemical vapor deposition, physical vapor deposition

19.17 How many elements of tool geometry are required to completely specify a single-point tool: (a) two, (b) five, (c) seven, (d) eight, or (e) ten?

seven

19.16 Sialon is a cutting tool material containing which of the following as its principal ingredients: (a) aluminum oxide, (b) cubic boron nitride, (c) silicon carbide, (d) silicon nitride, (e) titanium nitride, and (e) tungsten carbide?

silicon nitride, aluminum oxide,

19.19 Which of the following drill types would be the most likely choice to drill a hole with a 100 mm (4.0 in) diameter: (a) gun drill, (b) spade drill, (c) straight-flute drill, (d) twist drill?

spade drill

19.5 Which of the following are the three most important properties of a tool material that are suggested by the three modes of tool failure: (a) ductility, (b) hot hardness, (c) impact resistance, (d) tensile strength, (e) toughness, and (f) wear resistance?

toughness, hot hardness, wear resistance