Question 1

Single-point tool geometry: The angle between the tool face and a line tangent to the machined surface at the cutting point is called the rake angle, not the “cutting angle”. Is the given definition correct?

Accepted Answer

Introduction / Context: Precise terminology in tool geometry avoids confusion when setting up tools and analyzing forces. “Rake angle”, “clearance (relief) angle”, and “wedge angle” are distinct. The prompt statement labels a well-known definition with the wrong name, and this question checks recognition of the correct term. Given Data / Assumptions: Single-point turning tool with conventional nomenclature. Angles measured relative to the work surface and cutting velocity direction. No special reference system (ASA/ORS/NRS) complications beyond the basic meaning. Concept / Approach: The angle between the tool face and a line tangent to the just-machined surface at the cutting point corresponds to rake angle (positive, neutral, or negative). The “cutting angle” is not a standard geometric term by itself; more accurately, the wedge angle equals rake angle complement with clearance, i.e., wedge = 90° − rake − clearance (in a simplified 2D view). Step-by-Step Solution: Identify the definition in the statement → face vs tangent to machined surface.Map to standard terms → this describes rake angle.Conclude that calling it “cutting angle” is incorrect. Verification / Alternative check: Tool drawings, handbooks, and inserts catalogs consistently use “rake angle” for this definition; “cutting angle” is ambiguous and not preferred in scientific nomenclature. Why Other Options Are Wrong: Conditioning correctness on orthogonal/oblique or measurement system does not change the fundamental name “rake angle”. Common Pitfalls: Confusing rake angle with clearance angle; using nonstandard terms which lead to set-up errors and misinterpretation of chip formation behavior. Final Answer: Incorrect

Question 2

Broaching practice: Are push broaches used only for sizing holes, or can they also generate the hole profile?

Accepted Answer

Introduction / Context: Broaching is a multi-tooth process in which each successive tooth removes a small increment of material. A common misconception is that a push broach merely “sizes” a pre-formed hole. In practice, both push and pull broaches may be designed with roughing and finishing sections to generate the target geometry directly. Given Data / Assumptions: Through-holes or short blind holes in ductile materials. Proper starting hole (pilot) provided for chip accommodation and guidance. Broach design includes roughing teeth, semi-finishing teeth, and finishing lands. Concept / Approach: Push broaches are typically shorter and used on small parts, arbors, or press broaching. They commonly include cutting tooth rise to remove stock and a finishing section that brings the hole to size and form (e.g., keyway, polygon). Limiting them to “sizing” ignores the engineered progression of teeth that actually creates the final geometry. Step-by-Step Solution: Recognize broach structure → roughing to finishing teeth.Identify push broach applications → keys, splines, polygons, hex/square.Conclude → push broaches are not only for sizing; they cut and finish. Verification / Alternative check: Tool catalogs illustrate push broaches with full tooth sequences and chip breakers intended for geometry generation, not merely calibration of size. Why Other Options Are Wrong: Material or hole type does not fundamentally restrict a push broach to sizing. Pull-broaching is more common for long holes, but push broaches still cut, not just size. Common Pitfalls: Insufficient pilot hole or chip space causing jamming; misjudging the press tonnage needed because roughing teeth remove stock incrementally. Final Answer: Incorrect — push broaches can rough and finish to generate size and form

Question 3

Heat generation zones in metal cutting: The region where heat is produced by friction between the moving chip and the tool face is known as the…

Accepted Answer

Introduction / Context: In metal cutting, three principal regions are associated with energy conversion to heat: the primary shear zone, the chip–tool interface (friction zone), and the secondary deformation within the chip/tool contact. Correctly identifying these regions helps in choosing coatings, rake angles, and cutting parameters to manage temperature and tool wear. Given Data / Assumptions: Orthogonal or oblique cutting with a sharp tool. Continuous or discontinuous chips depending on material. Focus on the interface between chip underside and tool face. Concept / Approach: The shear zone (primary) is where the work material plastically deforms into chip, generating heat due to plastic work. The friction zone (chip–tool interface) is where the newly formed chip slides over the rake face, producing heat by sliding friction and secondary deformation. Distinguishing these zones clarifies why rake face coatings (e.g., TiAlN) and cutting fluids that reach the interface can lower temperature and reduce crater wear. Step-by-Step Solution: Identify heat due to plastic work → primary shear zone.Identify heat due to sliding on rake face → chip–tool friction zone.Select the correct name for the chip–tool area → friction zone. Verification / Alternative check: Temperature maps and tool wear patterns (crater wear) peak along the rake face contact, confirming the frictional and secondary deformation source of heat there. Why Other Options Are Wrong: “Work–tool contact zone” is a generic description, but the standard technical term is friction zone; “shear zone” is primary deformation; bulk heat in workpiece is a result, not the specific interface region. Common Pitfalls: Assuming all heat comes from shear only; neglecting coolant/coating roles at the interface; misattributing crater wear to only chemical diffusion rather than also frictional heating. Final Answer: friction zone

Question 4

Shaper operations: Which surfaces can be produced effectively on a shaper machine using appropriate tool and feed settings?

Accepted Answer

Introduction / Context: A shaper produces flat surfaces by a reciprocating single-point tool. By selecting tool geometry, clapper box angle, and table/swivel adjustments, the same machine can generate horizontal, vertical, and angular planes. This versatility makes shapers useful for toolrooms and maintenance work despite slower productivity than milling. Given Data / Assumptions: Standard shaper with adjustable tool head and swiveling vise or table. Rigid clamping and suitable feeds/speeds. Surface generation by linear strokes. Concept / Approach: Surface orientation follows relative motion between tool and work. With the work clamped at various angles or by tilting the tool head, one can sweep straight-line paths to form horizontal, vertical, and angular faces. Step-over feeds and multiple passes create the required plane size and finish. Step-by-Step Solution: For horizontal faces → align work surface parallel to tool path; use straight tool.For vertical faces → use side cutting tool; adjust tool head and feed direction.For angular faces → swivel vise/table or set tool head angle to desired inclination. Verification / Alternative check: Typical machine manuals list examples of all three surface types produced on shapers, including V-block sides, angular slides, and guideways. Why Other Options Are Wrong: Limiting shapers to a single orientation ignores the adjustability of tool head and work holding; keyways are a niche case and not the only application. Common Pitfalls: Poor clamping leads to chatter; incorrect clapper box setting can rub the return stroke; insufficient step-over planning leaves ridges on the surface. Final Answer: all of these

Question 5

Jigs and fixtures: Why is a diamond (diamond-shaped) locating pin used in a 2-pin location scheme for workholding?

Accepted Answer

Introduction / Context: In precision location, a common strategy is to use two pins: one round (fixed) and one diamond-shaped. This controls location in two orthogonal directions without over-constraining the part. The diamond pin permits thermal expansion and manufacturing variation along one axis while still preventing rotation. Given Data / Assumptions: Workpiece has two locating holes or slots. Fixture uses one round locating pin and one diamond locating pin. Goal is repeatable location without binding due to tolerances. Concept / Approach: The round pin fixes two degrees of freedom in the plane (X and Y at that hole) and rotation. The diamond pin, with its relieved flats, constrains the remaining needed degree perpendicular to the flat but allows slight movement along the flat. This avoids over-constraint when the hole center distance varies within tolerance, improving assembly and avoiding jamming. Step-by-Step Solution: Place the part on the round pin → primary location established.Engage the diamond pin → constrains only the needed axis, allowing float along the other.Result → accurate, repeatable location without stress or binding. Verification / Alternative check: GD&T-based fixture design texts recommend round + diamond pin schemes to control 4 in-plane DOF while accommodating center-distance tolerance and thermal effects. Why Other Options Are Wrong: Hardness and wear are benefits of hardened pins but not the unique reason for diamond geometry; space saving, clamp elimination, and inspection are unrelated to the functional advantage of the diamond profile. Common Pitfalls: Using two round pins of tight fit causing binding; misorienting the diamond pin flats relative to the tolerance direction; failing to harden pins for durability. Final Answer: It allows one direction to float, accommodating center-distance tolerance during assembly.

Question 6

Cylindrical grinding methods: In-feed (plunge) grinding is primarily used to…

Accepted Answer

Introduction / Context: Cylindrical grinding employs either traverse (longitudinal) or in-feed (plunge) modes. Selecting the proper mode depends on the geometry to be generated. In-feed grinding is suited for features where the wheel shape must be imparted directly onto the workpiece, such as shoulders, grooves, and complex forms. Given Data / Assumptions: Wheel face width equals or exceeds the required ground width. Work is located and rotating, but no significant axial movement during the plunge. Wheel may be dressed to a form to transfer geometry. Concept / Approach: In in-feed grinding, the wheel advances radially into the rotating work. Because there is no need to traverse along the axis, it is ideal for grinding shoulders or formed surfaces where the wheel shape defines the profile. For long cylindrical surfaces, traverse grinding is preferred to cover lengths greater than the wheel face. Step-by-Step Solution: Identify geometry → shoulder or form requiring wheel profile.Dress wheel to shape → accurate profile on wheel face.Plunge radially → profile transferred to work in one operation. Verification / Alternative check: Process charts categorize plunge grinding for short faces and forms; traverse for long lengths; taper grinding can also be done by swiveling the workhead or wheelhead, but shoulders/forms remain classic plunge targets. Why Other Options Are Wrong: Grinding long slender shafts is a traverse operation; producing tapers may be done by plunge with a formed wheel, but the quintessential application is shoulders/forms, not general long tapers; “all of these” is too broad. Common Pitfalls: Insufficient dressing accuracy causing profile errors; thermal expansion during plunge causing burn; inadequate coolant leading to surface checks. Final Answer: grind shoulders and formed surfaces in one plunge

Question 7

Surface finish in machining: What is the typical effect on surface finish when both depth of cut and feed rate are increased (other factors unchanged)?

Accepted Answer

Introduction / Context: Surface finish is influenced by geometric factors (feed marks), material behavior, and dynamics. Increasing feed and depth of cut changes chip load and cutting forces, which generally worsens roughness unless compensated by tool geometry, coatings, speed, or rigidity enhancements. Given Data / Assumptions: Same tool, nose radius, and cutting speed. Machine rigidity and damping unchanged. Homogeneous work material and stable cutting (no chatter onset considered separately). Concept / Approach: Geometrically, the theoretical roughness from feed marks increases with feed because scallop height is proportional to feed^2 divided by 8 * nose radius for turning. Larger depth of cut and feed also increase forces and heat, encouraging built-up edge and vibration, both of which further degrade finish. Step-by-Step Solution: Increase feed → larger scallop height → higher Ra and Rz.Increase depth of cut → higher forces/deflection → potential vibration and tearing.Net effect → rougher surface unless offset by a larger nose radius or other changes. Verification / Alternative check: Shop trials routinely show improved finish when reducing feed and using a larger nose radius or finishing pass at small depth of cut; cutting data tables specify separate roughing and finishing feeds/depths. Why Other Options Are Wrong: Improvement with higher feed/depth contradicts geometry; “no effect” ignores increased scallop height; mirror-like finish requires low feed, sharp tool, and stability. Common Pitfalls: Trying to correct a poor finish by only increasing speed while leaving feed and depth high; overlooking machine rigidity and tool overhang. Final Answer: Deteriorates

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