Question 1

Hacksaw blade tooth set: How are the teeth of a standard hacksaw blade typically set to reduce binding and improve chip clearance?

Accepted Answer

Introduction / Context: Tooth set on a hacksaw blade provides kerf width greater than blade thickness, reducing friction and preventing binding. Knowing the correct set pattern helps achieve straight cuts and longer blade life. Given Data / Assumptions: General-purpose hand hacksaw blades. Cutting a variety of metals with appropriate TPI. Goal: maintain kerf clearance and chip evacuation. Concept / Approach: Common tooth sets include raker and alternate sets. The raker set alternates right and left teeth, while every third (or sometimes fourth) tooth is left straight. This pattern clears chips, stabilises the cut, and minimises lateral wandering. A simple alternate set without a raker may be used on some blades, but the described raker set is the classic configuration for metal cutting hacksaws. Step-by-Step Solution: Ensure kerf width > blade thickness by setting teeth.Adopt raker set: Right, Left, Straight sequence repeating.This provides chip space and balanced side forces in the cut.Therefore, the correct description is the alternating set with every third or fourth tooth straight. Verification / Alternative check: Manufacturer data for bi-metal hacksaw blades lists raker set as the standard for fine-tooth blades used on metals. Why Other Options Are Wrong: Only-right or only-left set would deflect the blade and seize in the kerf. Random bending is unacceptable and dangerous. Some specialised blades have no set (ground set), but standard hacksaw blades do have set to form kerf. Common Pitfalls: Using the wrong TPI for material thickness; excessive feed leading to stripped teeth; ignoring lubrication on difficult materials. Final Answer: alternately towards right and left and every third or fourth left straight

Question 2

Drawing processes — mandrel usage: In which metalworking operation is a moving (floating) mandrel commonly used to support the work and control internal diameter?

Accepted Answer

Introduction / Context: Mandrels are internal supports used to control inside diameter, wall thickness, and ovality during forming. Recognising where a moving or floating mandrel is applied is central to understanding tube manufacturing sequences and achievable tolerances. Given Data / Assumptions: Tubes are reduced in diameter and/or thickness by drawing through a die. Internal support may be fixed, moving (floating), or plug-type. Goal is consistent inner geometry and surface finish. Concept / Approach: In tube drawing, a floating (moving) mandrel is entrained by lubricant and metal flow, positioning itself at the die throat. It shapes the internal surface while the die forms the external surface, controlling wall thickness and roundness. In wiredrawing, there is no internal cavity; in forging or machining, mandrels may be used, but the specific “moving mandrel” refers to tube drawing practice. Step-by-Step Solution: Identify need for internal support: hollow product → tube drawing.Select floating mandrel to minimise tooling length and ease threading.Die + mandrel combination sets outer and inner diameters.Therefore, moving mandrel usage corresponds to tube drawing. Verification / Alternative check: Process schematics of tube drawing show mandrel types: fixed, floating, and plug; wiredrawing lacks an internal tool. Why Other Options Are Wrong: Wiredrawing is solid; no mandrel needed. Metal cutting and forging may use arbors or cores in special cases, but not the floating mandrel of tube drawing. Press braking is sheet bending; mandrels are irrelevant. Common Pitfalls: Poor lubrication causing mandrel scoring; incorrect mandrel position leading to wall non-uniformity; excessive reduction per pass causing tube tearing. Final Answer: tube drawing

Question 3

Selecting hacksaw TPI for brass: For cutting brass sections with a hand hacksaw, which tooth density (teeth per 25 mm) is generally preferred for clean cutting without tooth snagging?

Accepted Answer

Introduction / Context: Choosing an appropriate teeth-per-25-mm (TPI) for a hacksaw depends on the material and section thickness. Brass is a relatively soft, ductile non-ferrous metal that can grab coarse teeth, leading to chatter and burring. A finer pitch promotes smooth cutting and better edge quality. Given Data / Assumptions: Work material: brass (bars, tubes, or profiles). Hand hacksaw with standard blade length. Objective: minimise burring and tooth snagging while maintaining reasonable feed. Concept / Approach: General guidance suggests at least two to three teeth in contact with the work thickness. For softer, gummy metals like brass, a finer pitch reduces the cutting load per tooth and prevents aggressive bite that can cause tearing. A 32 teeth per 25 mm blade is commonly selected for thin to medium brass sections, providing a balance between speed and finish. Step-by-Step Solution: Assess material and section: brass tends to burr and can chatter with coarse teeth.Choose a fine pitch to keep multiple teeth engaged simultaneously.From typical options, 32 teeth per 25 mm gives smooth action on brass.Therefore, select 32 as the preferred TPI. Verification / Alternative check: Workshop charts list 32 TPI for thin-walled tubing and non-ferrous alloys like brass and copper for better finish. Why Other Options Are Wrong: 14 TPI is too coarse and can snag, leaving rough edges. 24 TPI may work on thicker brass but usually gives a rougher finish than 32. 40 TPI is very fine and slow; it may clog and reduce productivity. 10 TPI is excessively coarse for brass hand cutting. Common Pitfalls: Poor blade tension; inadequate lubrication (kerosene or cutting fluid can improve finish); pressing too hard with fine TPI causing rapid dulling. Final Answer: 32

Question 4

Press tool selection — combining operations: Which die type is designed to perform a cutting operation together with a forming operation in a single press stroke?

Accepted Answer

Introduction / Context: Press tooling terminology distinguishes how operations are grouped in a stroke. Choosing the correct die reduces handling, improves throughput, and enhances dimensional consistency. This question clarifies the difference between compound and combination dies. Given Data / Assumptions: Cutting operations include blanking, piercing, notching. Forming operations include bending, drawing, embossing. We aim to combine different categories in one stroke. Concept / Approach: A compound die performs two or more cutting operations in one stroke (e.g., blanking + piercing). A combination die performs both cutting and forming in the same stroke (e.g., blanking and drawing). A progressive die performs operations in stages as the strip indexes through stations. Therefore, when both cutting and forming must occur simultaneously within one stroke, a combination die is specified. Step-by-Step Solution: Identify operation categories needed: one cutting + one forming.Match die terminology: cutting + forming together → combination die.Exclude dies intended for only cutting (compound) or staged operations (progressive).Hence, choose combination die. Verification / Alternative check: Tooling handbooks illustrate combination dies for blank-and-draw parts, confirming the definition. Why Other Options Are Wrong: Simple die executes a single operation only. Progressive die spreads operations across stations, not in one simultaneous stroke. Compound die groups cutting operations only; it does not include forming. Transfer dies move parts between dies, not necessarily combining operations in one stroke. Common Pitfalls: Confusing compound with combination; underestimating tonnage increases when forming is added; neglecting stripper and pressure pad design needed for drawing operations. Final Answer: combination die

Question 5

Oxy–acetylene welding gas usage: If a neutral flame is used throughout oxy–acetylene welding and both cylinders have the same capacity, will the oxygen and acetylene cylinders empty at approximately the same time?

Accepted Answer

Introduction / Context: Flame chemistry in oxy–fuel processes depends on the volumetric ratio of oxygen to acetylene. A neutral flame, commonly used for welding steels, aims for an approximately 1:1 volumetric ratio, producing neither oxidising nor carburising conditions. Gas consumption rates follow from this ratio. Given Data / Assumptions: Neutral flame with oxygen-to-acetylene ratio near 1:1. Welding (not cutting), where there is no separate cutting oxygen jet. Cylinders of equal nominal gas capacity. Concept / Approach: In welding with a neutral flame, the oxygen flow approximately equals acetylene flow. Therefore, if both cylinders start full and capacities are equal, their effective consumption causes both to deplete at roughly the same time. Deviations can occur due to regulator settings, nozzle size, or minor ratio tuning, but the principle stands. In contrast, oxy–fuel cutting uses an additional high-flow oxygen jet, making the oxygen cylinder empty much faster than the acetylene cylinder. Step-by-Step Solution: Set neutral flame: O2 flow ≈ C2H2 flow.Assume equal cylinder capacities and similar delivery conditions.Consumption parity implies similar depletion times.Therefore, the statement is correct for welding under neutral flame. Verification / Alternative check: Practice notes from welding manuals show oxygen and acetylene usage close to 1:1 for neutral welding flames, unlike cutting operations. Why Other Options Are Wrong: “Incorrect” confuses welding with cutting, where extra oxygen is used. Injector or equal-pressure torches do not change the basic flame ratio for neutrality. Nozzle size affects absolute flow but not the neutral ratio condition. Common Pitfalls: Assuming cutting ratios for welding; running slightly oxidising for speed and then observing faster oxygen depletion; ignoring that cylinder “capacity” references stored gas mass, not just pressure. Final Answer: Correct

Question 6

Pattern design — draft allowances by material: Compared with wooden patterns, metal patterns (e.g., aluminium) generally require what magnitude of draft allowance on vertical faces for easy withdrawal from sand moulds?

Accepted Answer

Introduction / Context: Draft is the taper provided on pattern faces parallel to the direction of withdrawal to facilitate clean release from the mould and prevent edge damage. The required draft depends on pattern material, surface finish, and moulding process. This question contrasts metal and wooden patterns. Given Data / Assumptions: Smooth, rigid metal patterns (e.g., aluminium or bronze) versus wooden patterns. Sand moulding using typical binders and permeability. Goal: minimise sticking and erosion during draw. Concept / Approach: Metal patterns typically have superior surface finish and dimensional stability compared with wood. They are less prone to swelling, warping, or surface roughness. As a result, lower draft angles are sufficient to ensure release from the sand. Wooden patterns, being rougher and more compliant, generally require higher draft to avoid tearing the mould. Step-by-Step Solution: Assess surface finish and rigidity: metals have smoother, stiffer faces.Lower friction and reduced tendency to stick allow smaller draft.Therefore, relative to wood, metal patterns require less draft.Apply process-specific guidelines to choose exact degrees (often 0.5–1.0% for metal vs. higher for wood). Verification / Alternative check: Foundry design tables list smaller recommended draft for metal patterns, confirming the relationship. Why Other Options Are Wrong: “More” contradicts improved release characteristics of metal patterns. “Same” ignores material and finish effects. “No draft” is risky; some draft is almost always recommended. Reverse draft would trap the pattern in the mould. Common Pitfalls: Neglecting mould hardness and moisture, which affect draw; forgetting that textured or knurled pattern areas may still need extra draft; overlooking core print draft requirements. Final Answer: less

Question 7

Workshop practice — hacksawing and kerf control In metalworking with a hand hacksaw, the slot (kerf) produced during cutting is __________ the actual blade width because of tooth set and clearance. Choose the most accurate relation.

Accepted Answer

Introduction / Context: The term kerf refers to the width of the material removed by a cutting tool. In hand hacksawing and power sawing operations, understanding why the kerf exceeds the blade's nominal thickness helps in precision fitting, minimizing material waste, and avoiding jamming of the blade in the cut. Given Data / Assumptions: Standard hand hacksaw blade with set teeth. Workpiece is a typical metal bar or plate. Normal cutting conditions with proper tension and lubricant (if used). Concept / Approach: Hacksaw teeth are given a tooth set (alternating left–right or wave set). This set displaces teeth slightly sideways relative to the blade body, creating a cut wider than the blade thickness. The kerf must exceed blade thickness to prevent binding from thermal expansion, chips, and minor misalignment, thereby ensuring free blade movement and straighter cuts. Step-by-Step Solution: Identify that tooth set spreads the cutting edges outwards from the blade body.Recognize that two flanks cut simultaneously, producing a slot wider than the blade stock.Conclude that kerf width > blade width under normal, sharp-tool conditions. Verification / Alternative check: Measuring a cut with feeler gauges or calipers typically shows kerf larger than blade thickness; manufacturers specify set values that directly add to kerf. Why Other Options Are Wrong: Equal to: ignores tooth set; Less than: physically impossible with set teeth; Cannot be predicted / depends only on cutting speed: kerf primarily depends on set geometry, not speed alone. Common Pitfalls: Using a worn blade with lost set causes rubbing and deviation; over-tensioning the frame can also distort the cut. Final Answer: greater than

Question 8

Sheet-metal operations terminology The process of punching many holes arranged in a regular, evenly spaced pattern across a sheet is termed “perforating.” Do you agree?

Accepted Answer

Introduction / Context: Manufacturing engineers must distinguish between similar-sounding sheet-metal processes. Perforating, punching, piercing, blanking, nibbling, and slotting create different features and patterns, and the correct term matters for tooling, costing, and quality planning. Given Data / Assumptions: A sheet is processed to create many holes. Holes are regularly spaced and follow a defined pattern (e.g., grids or decorative arrays). Operation uses punch–die sets on a press. Concept / Approach: Perforating is the punching of multiple, closely spaced holes, often small, in a systematic pattern across an area. It differs from single-hole piercing (isolated holes), from blanking (cutting the perimeter to separate a part), and from nibbling (progressively removing material with overlapping punches to approximate complex outlines). Step-by-Step Solution: Define target feature: many holes in regular array.Map to terminology: this is “perforating.”Confirm distinct from nibbling and slotting by pattern and outcome. Verification / Alternative check: Standards and press-shop handbooks classify perforated sheets by hole size, pitch, open area percentage, and pattern (staggered, straight row), aligning with the stated definition. Why Other Options Are Wrong: Disagree: contradicts established terminology; Nibbling creates approximate contours rather than regular multi-hole arrays; Slotting forms elongated slots, not arrays of circular holes; Hole diameter variability is not required to call it perforating. Common Pitfalls: Confusing perforating with laser drilling or waterjet processes; mixing up blanking (part removal) with punching (scrap removal). Final Answer: Agree

Question 9

Oxy–acetylene welding fundamentals Select the approximate maximum flame temperature achievable with an oxy-acetylene torch under ideal conditions.

Accepted Answer

Introduction / Context: Gas welding depends on flame temperature and chemistry. Knowing the approximate maximum flame temperature of oxy–acetylene helps in selecting processes, nozzles, and travel speeds for brazing, welding, and cutting operations. Given Data / Assumptions: Neutral oxy–acetylene flame with proper oxygen-to-acetylene ratio. Ideal mixing and standard atmospheric pressure conditions. Workpiece preheat or heat sink effects ignored for temperature rating. Concept / Approach: The inner cone of a neutral oxy–acetylene flame reaches about 3100–3200°C, sufficient to weld steels and many nonferrous alloys, and to braze at lower temperatures. Other fuel–oxygen combinations (e.g., oxy-hydrogen) possess different flame temperatures and characteristics. Step-by-Step Solution: Identify flame type: neutral oxy–acetylene.Recall typical max flame temperature ≈ 3200°C at the inner cone.Select the closest option 3200°C. Verification / Alternative check: Manufacturer charts for welding tips list flame temp near 3200°C; practical weld pool behavior on steel corroborates this capability. Why Other Options Are Wrong: 1800–2400°C undervalue the well-known capability of oxy–acetylene; 3800°C overstates typical achievable temperature for this fuel pair. Common Pitfalls: Confusing workpiece temperature with flame temperature; misadjusting torch to oxidising or carburising, altering effective heating. Final Answer: 3200°C

Question 10

Limit gauges — ring gauge application A ring gauge is most appropriately used to perform which dimensional check during inspection?

Accepted Answer

Introduction / Context: Limit gauges provide rapid pass–fail decisions for mass inspection without reading numerical values. Recognizing which gauge suits shafts versus holes is essential for shop-floor quality control and interchangeability of parts. Given Data / Assumptions: Ring gauge is a hardened, precisely sized ring, often with GO and NO-GO ends or zones. Workpiece features include external cylindrical elements (shafts, studs). Standard gauge tolerance systems apply (GO checks maximum material condition). Concept / Approach: Ring gauges verify external diameters: the GO ring should pass over a correct shaft (within size), while the NO-GO ring should not pass. Conversely, plug gauges (cylindrical ends) check internal diameters of holes. Feeler gauges assess clearances indirectly, not dimensional size limits of shafts. Step-by-Step Solution: Identify feature type: external cylinder → ring gauge.Apply GO/NO-GO principle to confirm size compliance quickly.Conclude ring gauge use is for shafts/studs, not holes. Verification / Alternative check: Inspection manuals specify plug gauges for holes and ring gauges for shafts; this pairing enables fast fit verification (e.g., H7/g6 fits). Why Other Options Are Wrong: Holes require plug gauges; clearances are measured with feelers or dial indicators; micrometer calibration uses gauge blocks or standards, not ring gauges alone. Common Pitfalls: Using worn gauges without periodic calibration; forcing NO-GO gauge leading to false acceptance or damage. Final Answer: Check the diameter of shafts or studs (external GO/NO-GO)

Question 11

File classification by cut density A hand file having about 50–60 teeth per 25 mm length is termed what class of file?

Accepted Answer

Introduction / Context: Files are categorized by coarseness (cut) such as rough, bastard, second cut, smooth, and dead smooth. Proper selection ensures efficient stock removal, good surface finish, and minimized clogging or chatter during hand finishing. Given Data / Assumptions: Tooth density is specified as 50–60 teeth per 25 mm (approximately per inch). Standard single-cut or double-cut file categories. General-purpose metal filing, not woodworking rasps. Concept / Approach: Coarser files (bastard, second cut) have fewer teeth per unit length and remove material faster but with rougher finish. Finer files (smooth, dead smooth) have higher tooth density and provide finer finishes. Typical ranges place bastard around mid-20s to low-30s teeth per 25 mm, second cut higher, smooth around 40–55, and dead smooth around 55–60+ depending on standards and manufacturer. Step-by-Step Solution: Interpret 50–60 teeth per 25 mm as a fine cut.Match to classification charts: this aligns with smooth to dead-smooth range.Select the nearest standard designation: “Smooth file”. Verification / Alternative check: Toolmaker catalogs and trade tables list smooth files roughly 40–55 TPI and dead-smooth around 55–60+ TPI; thus 50–60 sits in the smooth region leading into dead-smooth depending on brand. Why Other Options Are Wrong: Bastard and second-cut are coarser with fewer teeth; dead-smooth may start near 55–60+ but 50–60 typically falls under smooth; rasp files have very coarse individually raised teeth for wood. Common Pitfalls: Ignoring material type and clogging tendencies; using too fine a file for heavy stock removal reduces productivity. Final Answer: Smooth file

Question 12

Hand tools identification A gimlet is primarily classified as which type of hand tool in fitting and carpentry practice?

Accepted Answer

Introduction / Context: Recognizing common hand tools and their correct applications improves safety and work quality. A gimlet is often confused with awls or small drills, but it has a specific role in woodworking and light fitting jobs. Given Data / Assumptions: Traditional manual gimlet with a pointed screw tip and spiral flutes. Used primarily on wood or soft materials. No power tool attachment. Concept / Approach: A gimlet is a small hand boring tool used to start pilot holes for screws or to create small-diameter holes in wood. Its screw tip pulls the tool into the work without excessive force, while flutes remove chips. It differs from marking awls (which only indent surfaces) and from twist drills (which require a drill or brace and bit). Step-by-Step Solution: Identify physical features: screw tip + spiral flute.Match function: creates clean, small holes (boring).Conclude that a gimlet is a boring tool. Verification / Alternative check: Woodworking references classify gimlets under boring tools alongside bradawls and augers, used before inserting screws to prevent splitting. Why Other Options Are Wrong: Marking tools scribe lines, not holes; cutting tools for metal are different; measuring and holding tools serve unrelated functions. Common Pitfalls: Using excessive force causing tear-out; choosing too small a pilot leading to split wood; using a gimlet on metals beyond its design. Final Answer: Boring tool (for starting small holes in wood)

Question 13

Surface conversion coatings on steel The process used to form a thin, adherent phosphate coating on steel surfaces for corrosion protection and paint adhesion is called “parkerising.” State whether this is correct.

Accepted Answer

Introduction / Context: Surface treatments prepare steel for service and finishing. Phosphate coatings improve corrosion resistance and paint bonding on automotive and machinery components. The trade name “Parkerising” is widely used for manganese or zinc phosphate processes. Given Data / Assumptions: Base metal: carbon or low alloy steel. Chemical bath contains phosphate salts with accelerators. Typical thin crystalline coating. Concept / Approach: Parkerising (phosphating) chemically converts the steel surface into insoluble phosphate crystals. It is distinct from galvanising (zinc metal coating), anodising (oxide growth on aluminum/titanium), and bluing (oxide layer on steel). Phosphate layers also provide a good substrate for oils and paints. Step-by-Step Solution: Identify the stated coating: thin phosphate layer on steel.Relate to process names: parkerising is phosphating.Therefore, the statement is correct. Verification / Alternative check: Process datasheets specify weight per unit area and crystal morphology; salt spray tests show improved paint adhesion on phosphated steel. Why Other Options Are Wrong: Anodising targets aluminum, not steel; galvanising deposits metallic zinc rather than a phosphate conversion layer; stainless steels are less commonly parkerised due to chromium oxide passivation. Common Pitfalls: Poor cleaning before phosphating causes patchy coatings; incorrect bath control (pH/temperature) yields weak layers. Final Answer: Correct

Question 14

Casting methods — rotating moulds Identify the casting method in which molten metal is poured and allowed to solidify while the mould is revolving to develop centrifugal forces.

Accepted Answer

Introduction / Context: Casting processes exploit gravity, pressure, or centrifugal action to fill moulds. Knowing which process uses rotation helps select tooling for pipes, bushings, and rings where directional solidification and low-inclusion levels are beneficial. Given Data / Assumptions: Mould rotates about an axis during pouring and solidification. No expendable cores are needed for true centrifugal pipes (bore created by centrifugal action). Objective: dense, fine-grained outer surfaces. Concept / Approach: In centrifugal casting, rotation forces the molten metal to the mould wall, driving lighter inclusions and gases toward the inner diameter. Variants include true centrifugal (tubes), semi-centrifugal (wheels), and centrifugal investment casting. This differs from die casting (pressure-injected into a rigid die), slush casting (hollow thin shells by partially solidifying then pouring out excess), and non-rotating permanent mould casting. Step-by-Step Solution: Identify the rotating mould condition → centrifugal process.Match to products: pipes, sleeves, rings benefit from centrifugal action.Select “Centrifugal casting method”. Verification / Alternative check: Process produces characteristic inner shrinkage defects that are machined away; macrostructure shows radial segregation consistent with centrifugal solidification. Why Other Options Are Wrong: Die casting uses plunger-injection, not rotation; slush casting creates thin shells without rotation; permanent mould refers to reusable moulds but typically static during fill. Common Pitfalls: Insufficient rotational speed causing misruns; inadequate gating into the spinning mould yielding turbulence. Final Answer: Centrifugal casting method

Question 15

Hot working process selection Which hot working process is best suited for producing axisymmetric parts of circular cross-section (e.g., cones, hemispherical ends, cookware) that are symmetrical about the rotation axis?

Accepted Answer

Introduction / Context: Manufacturing of axisymmetric thin-walled components often uses spinning, a process distinct from forging or extrusion. Recognizing when to use hot spinning saves tooling cost and achieves smooth surfaces and uniform thickness for shells and end closures. Given Data / Assumptions: Part is axisymmetric and circular in cross-section. Material is ductile enough for hot or warm spinning. Desired wall thickness is relatively thin compared to diameter. Concept / Approach: In hot spinning, a circular blank (or preform) is pressed over a rotating mandrel using rollers, progressively shaping it into cones, domes, or parabolic forms. This differs from hot extrusion (bulk flow through a die), hot drawing (deep drawing of sheet into cups), and forging (bulk upsetting or drawing under compressive loads). Spinning excels at symmetric, hollow shapes with continuous curvature. Step-by-Step Solution: Identify geometry: axisymmetric shell.Select process that forms by incremental roller pressure on a rotating blank.Conclude hot spinning is most appropriate. Verification / Alternative check: Common products—gas cylinders ends, cookware, reflectors—are made by spinning; surface finish and dimensional control match process capabilities. Why Other Options Are Wrong: Forging targets bulk shapes not thin shells; extrusion makes long prismatic profiles; hot drawing forms cups but not complex, smooth-contoured domes as effectively without multiple redraws; roll bending forms cylindrical arcs, not closed axisymmetric shells. Common Pitfalls: Excessive thinning at edges; inadequate lubrication leading to surface tearing; not matching mandrel geometry correctly. Final Answer: Hot spinning

Question 16

Limit gauges — progressive type A progressive limit gauge is designed so that the “GO” and “NOT GO” members are arranged how?

Accepted Answer

Introduction / Context: Limit gauges implement the Taylor principle for checking maximum and minimum material conditions quickly. Progressive gauges speed up inspection by allowing both limits to be checked without withdrawing and reinserting the gauge. Given Data / Assumptions: Gauge body with stepped sections for GO and NOT GO checks. Feature under inspection is typically a slot, keyway, or similar dimension. Operator seeks rapid pass–fail assessment in one motion. Concept / Approach: In a progressive gauge, the GO section enters first; continuing insertion immediately meets the NOT GO step if the work is oversize/undersize beyond limit. This arrangement puts both functional limits on the same side to enable a single linear pass. In contrast, double-ended gauges place GO at one end and NOT GO at the opposite end, requiring repositioning. Step-by-Step Solution: Apply Taylor principle: GO checks all related features; NOT GO checks one element.Use stepped arrangement to verify limits progressively in one insertion.Therefore, progressive = both members on the same side (stepped). Verification / Alternative check: Metrology guides illustrate progressive plug/snap gauges showing stepped lands labeled GO then NOT GO along one approach direction. Why Other Options Are Wrong: Separate members defeat the progressive concept; end-to-end arrangement is a double-ended gauge, not progressive; random orientation is poor practice; single GO cannot check both limits. Common Pitfalls: Forcing gauges causing wear; ignoring periodic calibration leading to drift and false accept/reject. Final Answer: “GO” and “NOT GO” members on the same side in a stepped (progressive) arrangement

Question 17

Thermit (Aluminothermic) Welding — Identify the Key Advantages In fabrication and track maintenance, thermit welding produces molten steel at the joint using a chemical reaction. Which set of benefits correctly describes why this process is preferre…

Accepted Answer

Introduction / Context: Thermit (aluminothermic) welding is widely used for joining heavy sections such as railway rails and large steel components. The process forms molten steel in situ by an exothermic reaction, then feeds it into a properly prepared mold around the joint. Understanding its advantages clarifies where and why it is selected over arc-based methods. Given Data / Assumptions: Chemical heat source: aluminum powder reacting with iron oxide to produce molten steel. Molded joint geometry with preheating of the ends to be joined. Focus on metallurgical and thermal characteristics of the resulting weld zone. Concept / Approach: Because the weld metal is poured as a liquid into a mold, the entire joint cross-section is filled with molten metal almost simultaneously. The mass cools more uniformly than a narrow arc-fused bead, which helps reduce steep thermal gradients and the associated residual stresses. The large heat reservoir and controlled feeding further minimize porosity and shrinkage problems when the mold, gating, and preheat are correctly designed. Step-by-Step Solution: Recognize that the process casts a joint rather than fusing a thin bead.Uniform molten pool formation → relatively uniform cooling.Lower thermal gradient → reduced internal residual stresses.Therefore the most comprehensive choice is “all of the above”. Verification / Alternative check: Railway practice routinely uses thermit welding to achieve full-section joints with good stress distribution compared to localized arc passes. Why Other Options Are Wrong: Choosing any single advantage ignores the combined benefits that drive adoption.“None of these” contradicts well-established thermit welding characteristics. Common Pitfalls: Assuming thermit welds automatically have zero residual stress; they are minimized, not eliminated, and proper preheat and mold design still matter. Final Answer: all of the above

Question 18

Cold Working of Metals — Effects on Structure, Properties, and Accuracy During cold working operations (performed below recrystallisation temperature), which combined outcomes are typically observed?

Accepted Answer

Introduction / Context: Cold working processes such as cold rolling, drawing, swaging, and press forming plastically deform metals below their recrystallisation temperature. These processes influence microstructure, mechanical properties, and dimensional control. Knowing the combined effects guides process selection and heat-treatment planning. Given Data / Assumptions: Temperature: below recrystallisation for the alloy. Plastic deformation induces dislocations and work hardening. Tooling and presses provide good geometric control. Concept / Approach: Cold deformation increases dislocation density, distorting grains and producing texture (preferred orientation). This “work hardening” raises strength and hardness while lowering ductility. Because thermal expansion is minimal and elastic springback can be predicted, tight tolerances and fine surface finish are achievable, especially compared to hot working. Step-by-Step Solution: Microstructure: distortion and stored strain → option A true.Properties: work hardening boosts strength/hardness → option B true.Accuracy: low thermal effects allow close tolerances → option C true.Hence, the correct comprehensive choice is option D. Verification / Alternative check: Typical stress–strain curves show higher yield strength after cold working, and process capability studies confirm improved dimensional control. Why Other Options Are Wrong: Selecting only one benefit ignores the broader effect profile of cold working.“None of these” conflicts with established metallurgy. Common Pitfalls: Confusing increased strength with improved ductility; ductility generally decreases unless annealed afterward. Final Answer: all of the above

Question 19

Projection Welding of Dissimilar Metals — Where Should the Projection Be Made? When two different metals are to be joined by projection welding, on which piece should the projection be formed to balance heat generation and obtain a sound weld?

Accepted Answer

Introduction / Context: Projection welding localizes current and force through small raised features (projections). With dissimilar metals, differences in electrical and thermal properties strongly affect heat generation at the faying interface. Proper placement of the projection is essential for consistent nugget formation. Given Data / Assumptions: Dissimilar metals with different electrical conductivities and thermal conductivities. Weld quality depends on localized resistance heating at the interface. Electrode force and current are appropriately set for projection welding. Concept / Approach: Joule heat is I^2 * R * t. High local resistance at the projection concentrates heating. If one workpiece is highly conductive (thus tends to carry current away), forming the projection on that higher conductivity piece increases contact resistance at the raised feature, compensating for its heat-sinking tendency and promoting balanced interfacial heating. Step-by-Step Solution: Identify property mismatch: one piece is higher in electrical/thermal conductivity.Goal: maximize interfacial heat where weld nugget must form.Strategy: add projection on the higher conductivity piece to raise local contact resistance.Outcome: heat is focused at the interface, producing a sound nugget. Verification / Alternative check: Shop practice and standards recommend placing projections on the better conducting or thicker member to equalize heating. Why Other Options Are Wrong: Lower conductivity metal: already has higher resistance; additional projection can overheat that side.Density or melting point alone is not the controlling factor for resistance heating.Thickness-only rule ignores the primary electrical/thermal consideration. Common Pitfalls: Assuming projections should always be on the thinner or softer piece; conductivity governs heating effectiveness. Final Answer: higher conductivity metal

Question 20

Cup Drawing (Sheet Metal) — Identify the Stress States During the deep drawing of a cylindrical cup from a flat blank, which stress states are present in the flange and in the drawn wall?

Accepted Answer

Introduction / Context: Deep drawing transforms a flat sheet into a cup by forcing material to flow radially inward and then vertically along the punch. Stress states vary by region and dictate failure modes such as wrinkling, tearing, or earing. Given Data / Assumptions: Standard cylindrical cup drawing with blank holder pressure applied. Negligible bending effects compared to membrane stresses for the conceptual analysis. Isotropic sheet assumption for baseline reasoning. Concept / Approach: In the flange, material flows radially into the die; the circumferential (hoop) direction experiences compression, which can cause wrinkling if the blank holder force is insufficient. In the cup wall, the material is stretched longitudinally along the punch direction, creating tensile stress that can lead to wall thinning or tearing if excessive. Step-by-Step Solution: Analyze flange: radial inflow induces hoop compression → wrinkling tendency.Analyze wall: drawn over the die radius and along the punch → axial/longitudinal tension.Combine insights: compressive in flange and tensile in wall simultaneously.Therefore, both (a) and (b) are correct. Verification / Alternative check: Forming limit diagrams and draw ratio limits correlate failures with these respective stress states. Why Other Options Are Wrong: Only compression or only tension fails to represent the full mechanics of drawing.Shear-only description ignores dominant membrane stresses governing defects. Common Pitfalls: Confusing flange compression with wall compression; the wall is primarily in tension. Final Answer: both (a) and (b)

Workshop Technology Questions