Question 1

Drilling tool geometry: The obtuse angle included between the chisel edge and a cutting lip, as viewed from the end of a twist drill, is called what?

Accepted Answer

Introduction / Context: Understanding twist drill nomenclature is essential for accurate hole making and tool life. Several angles define how a drill cuts: point angle, helix (rake), lip clearance (relief), and chisel edge angle. The question specifically asks for the obtuse angle formed between the chisel edge and a cutting lip, as seen from the end of the drill. Given Data / Assumptions: A standard twist drill with two cutting lips and a chisel edge at the center. Viewpoint is the end view of the drill (looking at the point). Typical shop geometry values are assumed (e.g., point angle about 118°, chisel edge angle about 55°–60°). Concept / Approach: The chisel edge is the web portion that intersects the two lips. It does not cut effectively; instead, it extrudes material and contributes to thrust. The angle between this chisel edge and either cutting lip, measured in the end view, is known as the chisel edge angle and is obtuse by design to strengthen the web and manage thrust. Step-by-Step Solution: Identify the chisel edge at the drill center (web intersection).Locate a cutting lip radiating from the periphery to the center.Measure the included angle between the chisel edge and the lip in the end view.This obtuse included angle is the chisel edge angle, typically around 55°–60°. Verification / Alternative check: Compare with known definitions: point angle is the included angle between lips (roughly 118°), helix angle is the flute spiral angle, and lip clearance is the relief behind the lip. Only the chisel edge angle fits the description asked. Why Other Options Are Wrong: Helix (rake) angle: spiral of the flute, not an end-view angle between chisel edge and lip. Point angle: included angle between the two lips, not between chisel edge and a lip. Lip clearance angle: relief behind the cutting lip, measured in a different plane. Common Pitfalls: Confusing the point angle (between lips) with the chisel edge angle (between chisel edge and a lip). Also, assuming the chisel edge cuts; it mainly extrudes, increasing thrust. Final Answer: Chisel edge angle

Question 2

Grinding technology: The overall structure (spacing and openness) of a grinding wheel primarily depends on which factors?

Accepted Answer

Introduction / Context: Choosing a grinding wheel is not only about abrasive and bond. The wheel structure—how open or dense the wheel is—directly affects chip accommodation, wheel loading, and thermal behavior. Successful grinding requires matching structure to job conditions. Given Data / Assumptions: Structure refers to the relative spacing between abrasive grains. Other parameters (abrasive type, grit size, grade, bond) are held constant for comparison. We consider typical shop operations: rough grinding, finish grinding, and varying workpiece hardness. Concept / Approach: Open structures provide larger chip spaces and are preferred for soft, gummy materials or heavy stock removal to prevent loading. Denser structures support finer finishes on harder materials where chip volumes are lower. Thus, structure selection depends on work hardness, operation type, and finish requirement. Step-by-Step Solution: If work is soft/ductile → choose more open structure to reduce loading.If operation is roughing → open structure helps evacuate larger chips.If a fine finish is required → denser structure supports fine chip formation and surface quality.Therefore, structure depends on all listed factors. Verification / Alternative check: Manufacturer selection charts map structure numbers to application classes: roughing vs finishing and work material characteristics corroborate this logic. Why Other Options Are Wrong: Only hardness: ignores process intent and finish goals. Only operation nature: neglects work material response. Only finish: without considering chip load and material behavior, finish alone is insufficient. Common Pitfalls: Selecting a dense wheel for gummy materials leads to glazing and burn; conversely, overly open wheels can harm dimensional control on hard parts. Final Answer: All of these

Question 3

Chip formation in machining: Ductile materials generally produce which type of chips under typical cutting conditions?

Accepted Answer

Introduction / Context: Chip morphology reflects the deformation mechanics at the tool–work interface. Ductile materials (e.g., mild steel, aluminum) characteristically undergo continuous plastic flow, often creating continuous chips, sometimes accompanied by a built-up edge (BUE) on the tool. Given Data / Assumptions: Ductile work material with conventional cutting parameters. Standard sharp tool with appropriate geometry. No special chip breaker unless noted. Concept / Approach: In ductile cutting, the shear zone supports steady flow, yielding continuous chips. Under lower speeds, dull tools, or inadequate lubrication, material may weld intermittently to the tool face, forming and shedding BUE. This still produces a nominally continuous chip but with surface finish variations. Step-by-Step Solution: Recognize ductility → favors continuous chip formation.Assess cutting conditions: lower speed or poor lubrication → likely BUE on the tool.Hence, chip may be continuous without BUE or continuous with BUE depending on conditions.Therefore the most inclusive correct choice is “either (a) or (c)”. Verification / Alternative check: Surface finish often worsens when BUE forms. Increasing speed, using sharper tools, or applying cutting fluid reduces BUE and restores clean continuous chips. Why Other Options Are Wrong: Discontinuous chips: typical of brittle materials (cast iron, bronzes) or very hard conditions, not the usual ductile case. Only continuous chips or only continuous with BUE: too restrictive; both are possible for ductile materials. Common Pitfalls: Assuming BUE means discontinuous chips; BUE modifies the continuous chip and affects finish and forces but does not make chips inherently discontinuous. Final Answer: Either continuous chips or continuous chips with built-up edge

Question 4

Drilling production setup: To perform drilling, reaming, counterboring, and related operations on one workpiece efficiently, which machine arrangement is most suitable?

Accepted Answer

Introduction / Context: In production environments, several hole-making operations—drilling, reaming, countersinking, and counterboring—are often required on the same part. Minimizing setups reduces time and improves positional accuracy. Choosing the right drilling machine arrangement is key. Given Data / Assumptions: Multiple sequential operations on one workpiece. Desire to reduce handling and fixture changes. Typical shop equipment options are available. Concept / Approach: A gang drilling machine mounts several individual drilling heads (or spindles) in a line on one table. The workpiece is clamped once and moved along the line or brought under successive spindles, each set up for a specific operation (e.g., drill → ream → counterbore). This enables quick operation changes without re-clamping. Step-by-Step Solution: Identify need: sequential hole operations on same part.Select system that houses multiple tools ready to operate without changing setup.Gang drilling fits: each spindle is pre-set for an operation; move part to the next spindle.Therefore, the best choice is the gang drilling machine. Verification / Alternative check: Multiple spindle machines are ideal when many holes must be drilled simultaneously in a pattern. Radial drills suit large/heavy workpieces with flexible reach, and sensitive drills are for light, precise hand-fed drilling—not multi-operation production flow. Why Other Options Are Wrong: Sensitive drilling: great feel and accuracy for small work, but slow for multi-operation production. Radial drilling: flexible reach, not optimized for multiple sequential tools on one clamp. Multiple spindle: best for many holes at once, not for varied operations in sequence. Common Pitfalls: Confusing simultaneous multi-hole drilling (multiple spindle head) with sequential multi-operation processing (gang setup). Final Answer: Gang drilling machine

Question 5

Lathe operation vocabulary: The process of embossing a diamond-shaped pattern on a cylindrical workpiece surface is known as

Accepted Answer

Introduction / Context: Operators often need to improve grip on knobs, handles, and fasteners. Rather than removing material, a forming operation is used on the lathe to create a textured pattern that enhances friction and aesthetics. Given Data / Assumptions: Standard engine lathe operation. Use of knurling tool with hardened patterned wheels. Workpiece is cylindrical and free to rotate at low speed. Concept / Approach: Knurling is a cold-working process that displaces surface material using toothed rollers to produce patterns such as diamond or straight. It is not a cutting operation; it is a forming process that raises ridges on the surface. Step-by-Step Solution: Mount knurling tool and align with workpiece centerline.Engage tool with sufficient pressure to plastically deform surface.Feed along the axis to generate a consistent diamond pattern.This diamond textured finish is called knurling. Verification / Alternative check: Compare with other terms: facing squares an end; grooving cuts a recess; counterboring enlarges an existing hole with a flat bottom. None produce a diamond surface pattern. Why Other Options Are Wrong: Counterboring: enlarges and flats a hole entrance. Grooving: creates a groove; no surface texturing like a diamond. Facing: creates a flat end face; unrelated to patterning. Common Pitfalls: Running too high a speed or too little pressure causes double-tracking and irregular patterns. Proper knurl wheel pitch selection relative to diameter is essential. Final Answer: Knurling

Question 6

Milling cutter features: In a plain (slab) milling cutter, the chip space between the back of one tooth and the face of the next tooth is called the

Accepted Answer

Introduction / Context: Milling cutters have defined surfaces that control chip formation and evacuation. Correctly naming these surfaces helps in specifying regrinds, analyzing chip flow, and diagnosing loading problems. Given Data / Assumptions: Plain (slab) milling cutter with straight or helical teeth. Terminology per standard cutter geometry. We distinguish face, land, fillet, and gash. Concept / Approach: The gash (also called flute space on some cutters) is the chip pocket. It is the space behind a tooth where the chip is accommodated before being expelled. The land is the narrow surface immediately behind the cutting edge. The face is the surface on which chip flows off the cutting edge. The fillet is the curved transition at the tooth root. Step-by-Step Solution: Identify cutting edge and face where chip flows.Behind the cutting edge, a small land supports the edge strength.The larger cavity behind the back of one tooth and ahead of the next is the chip space → gash.Therefore, the correct term is “gash”. Verification / Alternative check: Handbooks and cutter drawings label these regions; chip capacity is tied to gash volume and affects feed capacity and loading. Why Other Options Are Wrong: Face: surface where chip slips; not the pocket. Fillet: the rounded root transition, not the main chip cavity. Land: the narrow support behind edge, not the space. Common Pitfalls: Confusing “land” with “gash” leads to incorrect regrind instructions and reduced chip space after excessive face relief grinding. Final Answer: Gash

Question 7

Single-point tool nomenclature: In the standard ASA system, how many elements make up a complete tool signature?

Accepted Answer

Introduction / Context: Tool signature concisely specifies the geometry of a single-point cutting tool. The American Standards Association (ASA) system uses a sequence of angles and a radius to fully define the tool's cutting geometry for setup and replication. Given Data / Assumptions: ASA tool signature convention is used. Angles are measured in a specified reference plane. Nose radius is included as a distinct element. Concept / Approach: A complete ASA signature has seven elements: back rake angle, side rake angle, end relief angle, side relief angle, end cutting edge angle, side cutting edge angle, and nose radius. Together, they govern chip flow, cutting forces, surface finish, and tool strength. Step-by-Step Solution: List elements: back rake + side rake.Add clearances: end relief + side relief.Add cutting edge orientations: end cutting edge angle + side cutting edge angle.Include nose radius as the seventh element. Verification / Alternative check: Compare with other systems (e.g., ORS/NRS) which use different reference planes but contain equivalent geometric information; ASA specifically enumerates seven elements. Why Other Options Are Wrong: Two, four, or five elements omit key angles or the nose radius, giving an incomplete definition. Common Pitfalls: Confusing rake with relief; rake directs chip flow, relief prevents rubbing. Omitting nose radius leads to chatter and poor finish prediction. Final Answer: Seven

Question 8

Cutting fluids in machining: What is the primary combined purpose of applying a cutting fluid during metal cutting operations?

Accepted Answer

Introduction / Context: Cutting fluids profoundly influence tool life, dimensional accuracy, and surface finish. They remove heat, reduce friction, and help evacuate chips, making them essential in many machining operations. Given Data / Assumptions: General turning, drilling, and milling contexts. Appropriate fluid type for material and operation (soluble oil, straight oil, synthetic). Correct delivery method (flood, MQL, through-tool) assumed. Concept / Approach: Heat generation is intrinsic to cutting. Cutting fluids absorb and carry away heat from the cutting zone, cooling both tool and work. They also lubricate the tool–chip and tool–work interfaces, lowering friction, which improves surface finish and reduces built-up edge. Chip flushing further stabilizes the process. Step-by-Step Solution: Cooling function → temperature control for tool and work.Lubrication → reduced friction and wear → smoother surfaces.Flushing → chip evacuation prevents recutting and scoring.Hence, all listed purposes are correct collectively. Verification / Alternative check: Tool life tests show significant improvement with proper coolant; surface roughness values decrease due to reduced friction and thermal distortion. Why Other Options Are Wrong: Single-purpose choices are incomplete; fluids generally serve multiple functions simultaneously. Common Pitfalls: Using the wrong fluid chemistry for the work material, or inadequate flow rate/aim, negates benefits and can even worsen results due to thermal shock. Final Answer: All of these

Question 9

Milling mechanics: In down milling (climb milling), how does the cutting force vary during a tooth’s engagement?

Accepted Answer

Introduction / Context: Understanding chip thickness variation is crucial in milling. In down (climb) milling, the cutter rotation is in the same direction as the table feed. This reverses the chip formation pattern compared to up (conventional) milling and strongly affects forces and surface finish. Given Data / Assumptions: Standard slab or end milling. Rigid setup with minimal backlash or compensated backlash. Normal feeds and depth of cut. Concept / Approach: Chip thickness h varies along the tooth path. In down milling, the tooth first meets the work at maximum chip thickness and exits at zero thickness. Cutting force is roughly proportional to instantaneous uncut chip thickness (and width and shear strength), so the force peaks at entry and decays to near zero at exit. Step-by-Step Solution: Define chip thickness trend in down milling: h_max at entry → h_min ≈ 0 at exit.Relate force F to h: F ∝ h * b * tau_s (b = width, tau_s = shear strength).Therefore, F_max at entry and decreases as the tooth advances.Conclusion: the statement is correct. Verification / Alternative check: Force dynamometer traces show a descending force profile for each tooth engagement in climb milling; the inverse occurs in up milling. Why Other Options Are Wrong: Minimum-at-entry profile describes up milling, not down milling. Constant or zero force is unrealistic in metal cutting. Common Pitfalls: Using climb milling on machines with backlash can cause a pull-in effect. Modern CNCs compensate backlash and often prefer climb milling for better finish and tool life. Final Answer: Correct: maximum at entry, reducing to minimum at exit

Question 10

Broaching tool design: A typical broach contains which types of teeth along its length?

Accepted Answer

Introduction / Context: Broaching is a high-productivity process in which a multi-tooth tool removes material in a single pass. The geometry and sequence of teeth on a broach are engineered to distribute cutting load and achieve final size and finish reliably. Given Data / Assumptions: Internal or surface broach with progressive rise-per-tooth (RPT). Work material and fixturing suitably chosen. Single-pass broaching operation. Concept / Approach: A broach is segmented into zones: roughing teeth remove most stock with larger RPT; semi-finishing teeth refine the geometry with smaller RPT; finishing teeth establish the final dimension and surface finish with minimal RPT. This progression manages forces and achieves accuracy without separate tools. Step-by-Step Solution: Start: roughing section → high material removal.Middle: semi-finishing → corrects form, reduces tool marks.End: finishing teeth → final size and surface finish.Therefore, a broach contains all these tooth types. Verification / Alternative check: Tool drawings list tooth height progression and sections labeled R, S, and F, confirming the staged design. Why Other Options Are Wrong: Only roughing or only finishing would either overload the tool or fail to achieve finish and accuracy. Only semi-finishing omits necessary bulk removal and final sizing. Common Pitfalls: Neglecting proper chip space (gullet) and coolant supply in roughing zone causes chip jamming; ensuring correct RPT distribution avoids chatter and tool wear concentration. Final Answer: All of these (roughing, semi-finishing, and finishing teeth)

Question 11

Cutting fluids for alloy steels In practical machining operations on alloy steels (turning, milling, drilling), which cutting fluid is most commonly preferred to provide extreme-pressure lubrication, reduce built-up edge, and control tool wear at el…

Accepted Answer

Introduction / Context: Choosing the correct cutting fluid for alloy steels is essential for tool life, surface finish, and process reliability. Alloy steels tend to work-harden and generate high cutting forces and temperatures. Fluids with extreme-pressure additives are often required to prevent adhesion and scoring. Given Data / Assumptions: Material: general alloy steels (not free-machining low-carbon steels). Operations: turning, milling, drilling, or tapping. Need: high lubricity and boundary film formation to withstand high local pressures and temperature. Concept / Approach: The best fluids for alloy steels supply boundary lubrication through chemically active additives. Sulphurised mineral oils react at hot contact zones to form iron sulfide films that reduce friction and welding at the tool–chip interface, improving tool life and finish. Emulsions (soluble oils) are excellent coolants but may offer insufficient EP performance for tougher steels unless fortified. Water or dry cutting typically give poor results in these conditions. Step-by-Step Solution: Identify the need for EP lubrication in alloy steel machining.Recognize sulphurised mineral oil as a classic EP fluid providing boundary films under pressure.Conclude it is the most commonly preferred choice for tough alloy steels. Verification / Alternative check: Shop practice and tool manufacturer handbooks recommend active or inactive sulphurised oils for alloy steels, especially for slow to moderate cutting speeds and operations like tapping or deep drilling. Why Other Options Are Wrong: Water: excellent coolant but zero lubricity; promotes rust and poor tool life.Soluble oil: better cooling, but without strong EP package it may not prevent seizure.Dry machining: generally unsuitable for alloy steels with conventional tooling.Compressed air: aids chip removal and slight cooling, not lubrication. Common Pitfalls: Using straight cutting oils without proper sulfur activation for heavy-duty work; ignoring compatibility of sulphurised oils with non-ferrous materials (staining risk). Final Answer: Sulphurised mineral oil

Question 12

Metallurgy and tool life Tool life is generally improved when which microstructural characteristic is present in the work or tool material during machining?

Accepted Answer

Introduction / Context: Tool life is influenced by cutting conditions and by the metallurgical structure of both the tool and the work. Finer microstructures typically machine more uniformly, reducing intermittent loads that accelerate wear or chipping. Given Data / Assumptions: Conventional machining (turning/milling) with standard tool materials. Comparison of coarse versus fine grain structures in the work metal. Other factors like speed and feed held constant. Concept / Approach: A fine grain size in the work metal tends to reduce heterogeneity, banding, and large hard second-phase particles that can cause micro-chipping and abrasive wear of the tool edge. Uniform deformation lowers cutting force fluctuations and heat spikes, extending tool life. While hard carbides in tool microstructure are essential for tool hardness, simply “more hard constituents” without balance can reduce toughness and lead to brittle failure. Step-by-Step Solution: Assess how work microstructure affects chip formation and edge loading.Recognize that fine grains cut more uniformly with lower peak stresses.Infer that tool life generally improves with smaller grain size in the work. Verification / Alternative check: Machining data often show improved machinability ratings after normalizing or refining grain size, which correlates with longer tool life at comparable parameters. Why Other Options Are Wrong: Large grain size: tends to promote uneven cutting and tear; can raise tool wear.Abundant hard constituents in the tool without proper balance can cause brittleness and chipping.Very coarse pearlite: increases hardness variations and abrasiveness. Common Pitfalls: Equating hardness alone with machinability; ignoring the balance between hardness and toughness in both tool and work. Final Answer: Small (fine) grain size in the work metal

Question 13

Recommended cutting speed for HSS on mild steel For machining a mild steel workpiece using a high-speed steel (HSS) tool under typical shop conditions, which average cutting speed is most appropriate?

Accepted Answer

Introduction / Context: Cutting speed selection is central to tool life and productivity. For HSS tools cutting mild steel, shop handbooks provide ranges that balance wear, heat, and finish. Too low wastes time; too high burns the edge. Given Data / Assumptions: Tool: HSS (uncoated), standard geometry. Material: mild steel (~0.15–0.25% C). Conventional coolant and feeds; average conditions. Concept / Approach: Typical speeds for HSS on mild steel are around 25–35 m/min for turning, depending on rigidity, coolant, and depth of cut. Values like 5–15 m/min are excessively conservative and uneconomical; 60 m/min is more suited to coated carbides. Step-by-Step Solution: Consult typical HSS speed charts for mild steel.Identify common midrange recommendation near 30 m/min.Select 30 m/min as the reasonable average speed. Verification / Alternative check: Machining handbooks and shop experience confirm acceptable tool life and finish near 30 m/min with HSS on mild steel. Why Other Options Are Wrong: 5, 10, 15 m/min: needlessly slow, poor productivity unless under severe constraints.60 m/min: typically too fast for HSS on mild steel; risk of rapid wear. Common Pitfalls: Ignoring feed and DOC interactions; failing to adjust speed for interrupted cuts or poor coolant delivery. Final Answer: 30 m/min

Question 14

Process sequence in hole making Considering typical workshop practice, which operation is performed first when producing an internal thread in a solid workpiece?

Accepted Answer

Introduction / Context: Internal threads are commonly produced in blind or through holes. Understanding the correct operation sequence ensures dimensional accuracy and prevents tool damage. Given Data / Assumptions: A solid workpiece requiring an internal thread. Conventional manual or CNC operations. Standard tools (drill, countersink/spotface, tap, reamer if needed). Concept / Approach: The usual order is: pilot/size drilling → optional countersink/spotface → tapping. If high precision is required before tapping (for thread class or alignment), reaming may be used to bring the hole to a precise size for forming threads (for thread-form taps or special processes), but for cut taps the drill size itself is chosen per thread chart. Boring is typically used for enlarging or correcting alignment of an existing hole, not the first step in solid stock. Step-by-Step Solution: Initiate by drilling the core hole to the recommended tap size.If a flat seat is required around the hole, perform spot facing after drilling (guided by the pilot).Proceed to tapping to cut the internal threads. Verification / Alternative check: Standard tapping charts list drill sizes first; production travelers typically schedule drilling before tapping. Why Other Options Are Wrong: Spot facing: usually follows drilling to create a flat seat around the hole.Boring: used to enlarge/true an existing hole, not to start from solid.Tapping: cannot precede drilling.Reaming: optional precision step, but not first. Common Pitfalls: Skipping countersink/chamfer before tapping can damage the first thread; using the wrong drill size leads to poor thread quality or broken taps. Final Answer: Drilling

Question 15

Machines where work rotates and tool is stationary Among the following boring machines, identify the one in which the workpiece rotates on a table while a stationary single-point tool performs the cutting (i.e., tool does not rotate).

Accepted Answer

Introduction / Context: Different boring machines achieve relative motion between tool and work in different ways. Recognizing which element rotates is fundamental for selecting setups and tooling. Given Data / Assumptions: Conventional shop machines: vertical and horizontal boring machines, jig borers. Stationary tool implies a non-rotating single-point tool taking a cut as the work turns. Cutting is analogous to turning operations on a lathe. Concept / Approach: In a vertical boring machine (often called a vertical turret lathe), the workpiece is mounted on a large vertical rotary table; the tool is held on a ram or turret and does not rotate. The rotating work under a stationary cutting tool produces the machining action. In horizontal boring, jig boring, and precision boring machines, the tool typically rotates (boring bar or spindle) while the work is stationary or only fed linearly. Step-by-Step Solution: Identify machine where the table rotates with the work.Confirm that the cutting element is a stationary single-point tool on rams/turrets.Select vertical boring machine as the correct answer. Verification / Alternative check: Machine manuals and training texts depict VTLs with rotating worktables and stationary tools, especially for large diameters. Why Other Options Are Wrong: Horizontal boring: rotating boring bar; work is fixed.Precision/jig boring: spindle rotates the tool for accurate holes; work is stationary.CNC drilling: tool rotation is fundamental. Common Pitfalls: Confusing vertical boring machines with vertical milling machines; in a VTL the work rotates, not the tool. Final Answer: Vertical boring machine (vertical turret lathe type)

Question 16

Wheel conditioning terminology in grinding What is the correct term for restoring a grinding wheel to its true geometry and correct shape after wear has altered it (i.e., correcting runout and profile)?

Accepted Answer

Introduction / Context: Grinding wheels gradually lose their intended geometry and surface condition due to loading, glazing, and uneven wear. Two distinct maintenance actions are used: dressing and truing. Given Data / Assumptions: Abrasive wheel used in surface or cylindrical grinding. Wheel has developed runout or lost its original profile. Objective is to restore geometry and cutting effectiveness. Concept / Approach: Truing: restores the wheel to concentric, correct form and runout-free condition; may also generate a desired profile.Dressing: conditions the wheel surface to expose sharp grains, remove loaded debris, and open the structure; it improves cutting action but does not necessarily correct geometry. Hence, when the shape is altered and must be corrected, truing is required. Step-by-Step Solution: Diagnose issue: out-of-true wheel or lost profile.Select truing to restore geometry and concentricity.Dress afterward to optimize wheel sharpness and porosity. Verification / Alternative check: Shop standards recommend truing first to correct form, followed by dressing passes to achieve sharp, open cutting action. Why Other Options Are Wrong: Dressing: improves sharpness and chip space but not geometry by itself.Facing/Clearing: nonstandard or vague terms in this context.Profiling only: a subset of truing; truing encompasses restoring overall geometry. Common Pitfalls: Attempting to dress a badly out-of-true wheel wastes time and can damage the work. Always true first, then dress. Final Answer: Truing

Question 17

Tooth geometry of plain milling cutters In a plain milling cutter, what is the name of the gash surface directly adjacent to the cutting edge upon which the chip initially flows and impinges?

Accepted Answer

Introduction / Context: Understanding tooth nomenclature on milling cutters helps in resharpening, specifying geometry, and predicting chip flow. The surface that guides the chip right at the edge is especially important for rake and cutting action. Given Data / Assumptions: Plain (slab) milling cutter with peripheral teeth. Standard terminology: face, land, fillet, lead. Chip exits along the tooth face. Concept / Approach: The face of a milling cutter tooth is the surface over which the chip flows immediately after being sheared by the cutting edge; it determines the rake angle. The land is a narrow surface behind the cutting edge (on the periphery) that provides strength and relief. The fillet is the curved surface blending the face and the body. The lead typically refers to axial advance in helical teeth or feed direction, not a tooth surface. Step-by-Step Solution: Identify the chip-flow surface adjacent to the edge.Relate it to rake geometry which is formed on the face.Conclude that the correct term is “face.” Verification / Alternative check: Machining handbooks illustrate face as the chip-bearing surface on milling teeth; relief and land are separate features. Why Other Options Are Wrong: Fillet: a blending radius, not the chip-flow surface.Land: narrow peripheral support area behind the edge, not the chip face.Lead: not a tooth surface term here; relates to helical advance. Common Pitfalls: Confusing land with face when inspecting small cutters; verify by locating the rake surface involved in chip flow. Final Answer: Face

Question 18

Geometry of a round-nose turning tool Evaluate the statement: “A round nose tool has no back rake and no side rake; only the nose radius defines its cutting geometry.”

Accepted Answer

Introduction / Context: Single-point round-nose tools are used for light finishing and contouring. Besides nose radius, rake and clearance angles strongly influence chip formation, forces, and finish. Given Data / Assumptions: General turning on a lathe. Round-nose profile at the cutting tip. Work materials and speeds vary. Concept / Approach: A round-nose tool still possesses geometric angles: back rake (in the feed direction), side rake (in the cutting direction), and clearances. These control effective rake at each point along the nose. The fact that the tool nose is rounded does not eliminate the necessity of rake angles; in practice, rakes are set to suit the work material (e.g., positive for aluminum, moderate for steels, near zero or slightly negative for certain bronzes/brass with specific geometries). Step-by-Step Solution: Identify that rake angles are independent parameters from nose radius.Recall that effective rake varies around the curved nose but originates from the chosen back and side rakes.Conclude the statement “no back/side rake” is incorrect. Verification / Alternative check: Tool grinding charts for round-nose tools explicitly specify back rake, side rake, and clearances, along with nose radius. Why Other Options Are Wrong: Material-specific qualifiers do not make the base statement true; rake remains a design variable.Speed does not nullify the need for rake geometry. Common Pitfalls: Assuming nose radius alone governs finish; ignoring rake can increase forces and cause chatter or built-up edge. Final Answer: Incorrect

Question 19

Rotary transfer devices and fixture float In a rotary transfer machining system, what is the primary purpose of providing a floating (self-adjusting) position for the work-holding fixture at a station?

Accepted Answer

Introduction / Context: Rotary transfer machines index workpieces between multiple stations. Small index errors or stack-up tolerances can degrade positional accuracy unless mitigated. Floating fixtures help achieve precise alignment at each station. Given Data / Assumptions: Rotary transfer device with multiple machining heads. Fixtures can float slightly before being clamped. Tooling provides final datum alignment. Concept / Approach: A floating fixture allows minor compliance so that dowels, pilots, or tooling locators at each station pull the workpiece into exact position before clamping. This minimizes cumulative index error effects and improves repeatability of critical dimensions. It does not directly change indexing dynamics or drive kinematics; any cycle time reduction is secondary, arising from fewer reworks. Step-by-Step Solution: Recognize potential misalignment from indexing and tolerance stack-up.Enable fixture float to let station locators define the final position.Clamp after alignment → improved positional accuracy. Verification / Alternative check: Manufacturers specify floating bushings/locators on transfer lines for precision features, demonstrating measurable reduction in positional variation. Why Other Options Are Wrong: Over-index reduction: controlled by indexer design and locks, not fixture float.Acceleration/deceleration: a drive issue, not fixture compliance.Cycle time: not directly reduced; quality and capability are the focus. Common Pitfalls: Locking the fixture rigidly before locating results in forced fits and part distortion; always float then clamp. Final Answer: Improve the accuracy of location by self-alignment with tooling

Question 20

Planer kinematics in shaping large work Which description correctly characterizes the fundamental motion in a planer during machining?

Accepted Answer

Introduction / Context: Planers and shapers are often contrasted by which element reciprocates. Understanding this difference guides fixture design and selection of machine for very large components. Given Data / Assumptions: Traditional double-housing planer or open-side planer. Single-point tool mounted on a tool head or rail. Large, heavy workpieces requiring long strokes. Concept / Approach: In a planer, the work table carrying the workpiece reciprocates linearly beneath a stationary cutting tool (except for feeds and small positioning motions). This arrangement allows massive workpieces to be machined with reduced moving tool mass, improving rigidity. By contrast, in a shaper the tool ram reciprocates while the work remains stationary on a small table. Step-by-Step Solution: Identify planer: moving table (work reciprocates), stationary tool (with feed movements).Recognize suitability for large parts due to robust table drive and supports.Select the option that matches these motions. Verification / Alternative check: Machine tool texts: “Planer → work reciprocates; Shaper → tool reciprocates.” Why Other Options Are Wrong: Stationary work with reciprocating tool describes a shaper, not a planer.Other options add motions (continuous/circular/rotary) not present in planing. Common Pitfalls: Confusing planer with plano-miller (where rotating cutters mill while the table feeds slowly); planing uses single-point cutting with reciprocation. Final Answer: Tool is stationary and work reciprocates under the tool

Production Engineering Questions