Q: Machining titanium: key reason it is difficult to machine Identify the primary reason machining of titanium alloys is difficult and leads to rapid tool wear and poor chip control. Choose the correct statement.

Given facts Titanium has low thermal conductivity (heat concentrates at the cutting edge). It is chemically reactive at cutting temperatures, promoting adhesion (galling) and diffusion wear. Concept/Approach The dominant issue is tool–work chemical affinity at high temperature, which causes built-up edge, notching, and diffusion wear. Low thermal conductivity exacerbates the temperature rise, but option (a) incorrectly states it as high. Final Answer Chemical reaction/adhesion between tool and work material

Q: Silicon carbide (SiC) abrasive: typical grinding applications For which materials is silicon carbide abrasive chiefly used in grinding operations? Choose the most appropriate option.

Concept/Approach Silicon carbide (SiC) wheels are sharp and hard but relatively brittle; they are well suited for grinding hard, brittle, and short-chipping materials. Applications Cemented carbides (green SiC) Ceramics (alumina, porcelain, etc.) Cast iron (gray/white) and nonferrous metals Final Answer All of these

Question 1

Tool wear behavior of cemented carbide with speed  For a cutting tool made of cemented carbide, at which cutting speeds does wear occur fastest? Choose the most appropriate range.

Accepted Answer

Concept Carbide tools withstand higher speeds than HSS, but tool wear still accelerates with increasing cutting speed (Taylor's tool life relation: V Tn = C). At the highest speeds, thermal and diffusion wear mechanisms dominate. Final Answer Very fast speeds.

Question 2

Lathe lead screw thread selection  In a standard engine lathe, the lead screw typically uses which type of thread start configuration? Choose the correct option.

Accepted Answer

Reasoning The lead screw must transmit motion accurately and robustly to the carriage for thread cutting; single-start (often square/Acme form) provides strength and a precise, predictable lead. Contrast Multi-start threads are used for quick traverse/feed screws, not typically for the lead screw. Final Answer Single-start.

Question 3

Milling machine: where is the cutting tool mounted?  Identify the correct component on which the milling cutter is mounted (general shop practice context). Choose the correct option.

Accepted Answer

Shop context and assumption In conventional horizontal milling machines, the cutter is mounted on an arbor, which is supported by the spindle and overarm. (In vertical milling, certain cutters mount directly in the spindle, but the common textbook answer for this general question is “arbor”.) Final Answer Arbor.

Question 4

Cutting mechanics classification: drilling as a cutting operation  Drilling with a twist drill is classified under which cutting mode? Choose the correct option.

Accepted Answer

Concept Orthogonal cutting assumes a straight cutting edge perpendicular to cutting velocity. Drilling uses a helical cutting edge with inclination; chip flow is not in a plane normal to the cutting edge → it is oblique cutting. Final Answer Oblique cutting.

Question 5

Single-point tool geometry: typical lip (included) angle range  For a standard single-point cutting tool, the usual lip angle (included angle at the cutting edge) lies in which range? Choose the correct option.

Accepted Answer

Reference values Typical single-point tools use a lip (included) angle roughly between 60° and 80°, balancing strength and sharpness based on work material and operation. Final Answer 60° to 80°.

Question 6

Cylindrical grinding: typical work/surface speed range  Select the usual range of workpiece surface speed used in cylindrical grinding. Choose the correct option.

Accepted Answer

Concept In cylindrical grinding, the wheel speed is very high (often ~1500–2000 m/min), while the work surface speed is modest for control of heat and finish, commonly around 20–30 m/min. Final Answer 20 to 30 m/min.

Question 7

Single-point tool angles: definition of side rake angle Choose the correct description of the side rake angle of a single-point cutting tool. Select the accurate definition.

Accepted Answer

Definitions Side rake angle: inclination of the tool face sideways to assist chip flow across the tool.Back rake angle: inclination of the tool face towards the shank/back of the tool. Why others are incorrect (C) and (D) describe clearance/relief angles, not the side rake. Final Answer The angle by which the face is inclined sideways.

Question 8

Tool materials: increasing ability to retain hot hardness (red hardness)  Arrange the given tool materials in order of increasing ability to retain hardness at elevated temperature (lowest → highest): carbide, ceramic, cermet, borazon (CBN). Choose …

Accepted Answer

Concept/Approach Hot hardness (red hardness) is a tool material's ability to retain hardness and resist softening at high cutting temperatures. In general across common cutting materials: carbide < ceramic < cermet < cubic boron nitride (borazon) in hot-hardness capacity. Reasoning Tungsten-carbide tools are strong but lose hardness sooner than ceramics/cermets at higher temperatures. Advanced cermets and ceramics perform better at elevated temperatures, while CBN (borazon) exhibits excellent hot hardness, second only to diamond and preferred on hardened steels. Final Answer carbide, ceramic, cermet, borazon

Question 9

Machining titanium: key reason it is difficult to machine  Identify the primary reason machining of titanium alloys is difficult and leads to rapid tool wear and poor chip control. Choose the correct statement.

Accepted Answer

Given facts Titanium has low thermal conductivity (heat concentrates at the cutting edge). It is chemically reactive at cutting temperatures, promoting adhesion (galling) and diffusion wear. Concept/Approach The dominant issue is tool–work chemical affinity at high temperature, which causes built-up edge, notching, and diffusion wear. Low thermal conductivity exacerbates the temperature rise, but option (a) incorrectly states it as high. Final Answer Chemical reaction/adhesion between tool and work material

Question 10

Silicon carbide (SiC) abrasive: typical grinding applications  For which materials is silicon carbide abrasive chiefly used in grinding operations? Choose the most appropriate option.

Accepted Answer

Concept/Approach Silicon carbide (SiC) wheels are sharp and hard but relatively brittle; they are well suited for grinding hard, brittle, and short-chipping materials. Applications Cemented carbides (green SiC) Ceramics (alumina, porcelain, etc.) Cast iron (gray/white) and nonferrous metals Final Answer All of these

Question 11

Drill with zero rake: identify the tool type  A drill that effectively has zero rake angle (scraping action) is termed what? Choose the correct name.

Accepted Answer

Concept/Approach A flat (spade-type) drill removes material primarily by a scraping/zero-rake action, unlike twist drills which have positive rake cutting lips and helical flutes for chip evacuation. Final Answer Flat drill

Question 12

Chip formation: materials producing segmental (discontinuous) chips  Segmental or discontinuous chips are most commonly formed during machining of which material? Choose the correct option.

Accepted Answer

Concept/Approach Segmental (discontinuous) chips occur with brittle materials that fracture ahead of the tool rather than plastically flow. Examples Cast iron and some bronzes tend to produce discontinuous chips. Mild steel generally produces continuous or built-up edge chips. Final Answer Cast iron

Question 13

Cutting velocity definition in machining  Evaluate the statement: “The velocity of the tool relative to the workpiece is known as the cutting velocity.” Choose the correct truth value.

Accepted Answer

Definition Cutting velocity is the relative surface speed at the tool–work interface (e.g., πDN for turning; peripheral speed of cutter teeth for milling; drill lip speed for drilling). Final Answer True

Question 14

Recommended HSS cutting speed: turning brass  Select the typical average cutting speed range for turning brass using a high-speed steel (HSS) tool under standard conditions. Choose the best range.

Accepted Answer

Concept/Approach Brass is free-cutting and allows relatively high cutting speeds compared with steels for the same tool material. For HSS tools, a common shop range for turning brass is around 90–120 m/min. Note Actual choice depends on tool geometry, rigidity, coolant, and surface finish requirements. Final Answer 90 to 120 m/min

Question 15

Twist drill material selection  Twist drills are commonly manufactured from which materials? Choose the most accurate option.

Accepted Answer

Facts Twist drills are widely produced from high speed steel (HSS) for performance and from high-carbon tool steels for economy/low-duty uses. Stainless steel is generally not used as a drill material. Final Answer Either (a) or (b)

Question 16

High-volume production of small, slender parts: machine tool choice  Which machine gives maximum production efficiency for small, long, and slender turned parts? Choose the correct lathe type.

Accepted Answer

Concept/Approach Sliding headstock automatic (Swiss-type) lathes support the work with a guide bushing very close to the tool, ideal for producing long, slender, small-diameter parts at high rates. Comparison Watchmaker's lathe: precision hand/bench work, not highest throughput. Multispindle/capstan: high productivity on short parts; less ideal for very slender lengths. Final Answer Sliding headstock automatic lathe (Swiss-type)

Question 17

Push broach vs. pull broach: geometric and cutting differences  Compared to a pull broach, a push broach typically: Choose the correct set of characteristics.

Accepted Answer

Concept/Approach Push broaches work in compression, so they are kept short and stiff to prevent buckling. They carry fewer progressive teeth and hence remove smaller stock per pass compared to long pull broaches that operate in tension. Final Answer All of the above

Question 18

Oblique cutting mechanics: chip-thickness distribution along the cutting edge  In an oblique cutting system (helical/inclined cutting edge with chip flow not perpendicular to the edge), where does the maximum chip thickness tend to occur across the …

Accepted Answer

Concept In oblique cutting, the cutting edge is inclined and chip flow is three-dimensional, deflecting sideways (in the direction of the chip flow angle). This causes a non-uniform chip thickness distribution along the edge rather than a peak at the middle. Why the statement is false Because chip flow is biased toward one side, the effective rake and local shear conditions vary along the edge. The thickest chip typically appears nearer the side where chip accumulates/flows, not at the mid-span. Common pitfall Assuming orthogonal-cutting intuition (uniform across width) applies to oblique cutting. It does not; the flow is inherently three-dimensional. Final Answer False — the maximum occurs nearer one side due to chip side-flow.

Question 19

Definition check: what is a fixture in manufacturing? Multiple closely related shop devices are listed (jig, fixture, gauge). Choose the correct definition of a fixture.

Accepted Answer

Key term separation Jig: holds/locates the workpiece and guides the tool.Fixture: holds/locates the workpiece only; does not guide the tool.Gauge: checks accuracy (dimensions/geometry). Correct choice Therefore, a fixture is “a device that holds and locates a workpiece during an inspection or a manufacturing operation”. Final Answer A device that holds and locates a workpiece during an inspection or a manufacturing operation.

Question 20

Lathe practice: feed direction for a round-nose turning tool  A round-nose tool is used for turning/finishing on a lathe. Can it be fed from left→right or right→left along the bed? State the correct evaluation.

Accepted Answer

Concept A round-nose tool has a symmetric profile about its nose radius, so for straight turning/finishing it can be used with feed in either direction provided the tool geometry (rakes/clearances) and setup are appropriate. Practical note Ensure adequate clearance and chip evacuation in the chosen direction; otherwise surface finish may be affected. Final Answer True — either left→right or right→left is acceptable.

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