Engineering Technician (EngTech) Application of Practical Engineering Knowledge and Skills Syllabus

On a metric micrometer, what is the standard pitch of the spindle thread and the resolution of the thimble (with 50 divisions)?

The standard spindle thread pitch is $0.5$ mm, so one full turn of the thimble advances the spindle $0.5$ mm. With 50 divisions on the thimble, the resolution is $\frac{0.5}{50} = 0.01$ mm. Reading = sleeve (main) reading + thimble division reading.

What is 'marking out' in workshop practice, and name three common marking-out tools.

Marking out is transferring dimensions and reference lines from a drawing onto the workpiece/material before cutting or machining. Common tools include: scriber (scribes lines), engineer's square (right angles), odd-leg/Jenny calipers, dividers (arcs/circles), centre punch (locating drill points), surface gauge/height gauge, and engineer's blue (marking dye).

Why is a centre (dot) punch used before drilling a hole?

A centre punch creates a small conical indentation at the marked centre. This indentation locates the drill point and stops the drill bit from 'wandering' or skating across the surface when starting the hole, ensuring the hole is drilled accurately on the marked-out position.

What is a datum (reference) when marking out or dimensioning, and why is using a single datum preferred?

A datum is a reference edge, surface, line, or point from which dimensions and measurements are taken. Using a single datum (datum dimensioning) is preferred because it prevents the accumulation of tolerance errors (tolerance stack-up) that occurs when each dimension is measured from the previous feature (chain dimensioning).

Classify material removal processes by giving two examples each of cutting, abrasive, and non-traditional methods.

Cutting (chip-forming): turning, milling, drilling, sawing. Abrasive: grinding, honing, lapping, sand/grit blasting. Non-traditional (no mechanical chip): EDM (electrical discharge machining), laser cutting, water-jet cutting, chemical/electro-chemical machining. Cutting and abrasive remove material mechanically; non-traditional use thermal, electrical, or chemical energy.

What is the difference between turning and milling as machining processes?

In turning, the workpiece rotates while a single-point cutting tool moves linearly to remove material — used for cylindrical features on a lathe. In milling, the cutting tool rotates (multi-point) while the workpiece is fed against it — used for flat surfaces, slots, and complex profiles on a milling machine.

State the formula for cutting (spindle) speed in turning/milling and define the symbols.

$$N = \frac{1000 \, v_c}{\pi D}$$ where $N$ is spindle speed in rev/min, $v_c$ is the cutting speed in m/min, and $D$ is the diameter in mm (workpiece diameter in turning, or tool diameter in milling). This converts a required surface cutting speed into a machine spindle speed.

Name three common forming processes that shape material without removing it, and state whether they are typically hot or cold.

Forging (usually hot — shaping by compressive blows/pressure), rolling (hot or cold — reducing thickness between rollers), bending/press-braking (usually cold), drawing and deep-drawing (usually cold), extrusion (hot or cold). Forming reshapes material by plastic deformation, conserving volume rather than producing chips/swarf.

What is 'springback' in sheet-metal bending and why must it be compensated for?

Springback is the elastic recovery of the metal after the bending force is removed, causing the bend angle to open up slightly from the formed angle. It must be compensated for by 'over-bending' (bending to a tighter angle) so that after springback the part reaches the intended final angle. It increases with higher material strength and larger bend radius.

Classify the main joining methods into permanent and non-permanent (semi-permanent) categories with examples.

Permanent joints: welding, brazing, soldering, riveting, adhesive bonding (cannot be separated without damage). Non-permanent (temporary/removable) joints: bolts/screws/nuts, clips, snap-fits, keys, splines (can be disassembled without destroying parts). Selection depends on whether the joint needs to be dismantled for maintenance.

What is the key difference between welding, brazing, and soldering?

Welding melts and fuses the parent (base) metals together (often with filler), forming a joint as strong as the base metal. Brazing joins parts using a filler metal melting above 450°C without melting the base metals (capillary action). Soldering is the same principle but with filler melting below 450°C, giving a lower-strength joint. Distinguishing temperature between brazing and soldering is $450\,^{\circ}\mathrm{C}$.

In welding, what do the abbreviations MIG/MAG and TIG stand for, and what shielding do they use?

MIG = Metal Inert Gas, MAG = Metal Active Gas — both use a continuously fed consumable wire electrode shielded by gas (inert e.g. argon for MIG, active e.g. CO2 mix for MAG). TIG = Tungsten Inert Gas — uses a non-consumable tungsten electrode with separate filler rod, shielded by inert gas, giving high-quality precise welds.

What is the difference between a clearance fit, a transition fit, and an interference fit?

Clearance fit: there is always a gap — the hole is larger than the shaft (parts move/slide freely). Interference (press) fit: the shaft is always larger than the hole — parts must be forced together and stay fixed. Transition fit: the limits overlap so the result may be a slight clearance or slight interference (used for accurate location).

During assembly, why are bolts on a flanged joint (e.g. cylinder head) tightened in a specific sequence and to a specified torque?

Tightening in a criss-cross/star sequence and in graduated torque steps ensures the load is distributed evenly across the joint, preventing distortion, uneven gasket compression, and leaks. The specified torque produces the correct bolt tension (clamping force) — too little risks loosening, too much risks stretching/snapping the bolt or stripping threads.

State the relationship between applied torque and bolt clamping force, and define the symbols.

$$T = K \, F \, d$$ where $T$ is the tightening torque, $F$ is the bolt clamping (preload) force, $d$ is the nominal bolt diameter, and $K$ is the nut/torque factor (typically around 0.2, depending on friction/lubrication). It shows torque is proportional to the clamping force for a given bolt size and friction condition.

Compare reactive (breakdown), preventive, and predictive (condition-based) maintenance strategies.

Reactive (run-to-failure): repair only after a breakdown — low planning, but causes unplanned downtime. Preventive (planned/scheduled): maintenance at fixed time/usage intervals to prevent failure — reduces breakdowns but may service components unnecessarily. Predictive (condition-based): monitor actual condition (vibration, temperature, oil analysis) and act only when data indicates impending failure — optimises cost but needs monitoring equipment/skills.

What is Planned Preventive Maintenance (PPM) and give two examples of routine tasks it includes.

PPM is maintenance carried out at predetermined intervals (time, running hours, or cycles) to keep equipment in good condition and reduce the chance of failure. Routine tasks include: lubrication/greasing, cleaning, inspection, tightening fasteners, replacing filters/belts, checking fluid levels, and calibration checks.

What does the maintenance metric MTBF stand for and what does a higher MTBF indicate?

MTBF = Mean Time Between Failures, the average operating time between failures of a repairable item: $$\mathrm{MTBF} = \frac{\text{total operating time}}{\text{number of failures}}$$ A higher MTBF indicates greater reliability — the equipment runs longer on average before failing. (MTTR, Mean Time To Repair, measures maintainability.)

How is the availability of a system calculated from MTBF and MTTR?

$$\text{Availability} = \frac{\mathrm{MTBF}}{\mathrm{MTBF} + \mathrm{MTTR}}$$ where MTBF is the mean time between failures (reliability) and MTTR is the mean time to repair (maintainability). High availability requires both long time between failures and short repair times.

Describe the six-step systematic approach to fault diagnosis.

A common sequence: (1) Collect information/observe symptoms; (2) Analyse the evidence against how the system should work; (3) Identify/locate possible fault areas; (4) Determine and test the most likely cause; (5) Rectify the fault (repair/replace); (6) Verify by re-testing that the system functions correctly and record/document the work. This logical method avoids random trial-and-error.

What is the 'half-split' (binary search) method of fault finding and why is it efficient?

Half-split means testing at the midpoint of a system (e.g. a signal chain) to determine which half contains the fault, then repeatedly halving the faulty section until the fault is isolated. It is efficient because each test roughly halves the number of remaining possibilities, locating a fault in a series system with far fewer tests than checking each stage in turn.

Distinguish between the symptom, the cause, and the effect of a fault, with an example.

The symptom is the observable indication that something is wrong (e.g. a machine overheats). The cause is the underlying reason (e.g. a blocked coolant filter). The effect is the consequence if not corrected (e.g. seized bearing/shutdown). Effective diagnosis traces from symptom to root cause rather than just treating the symptom.

What is the difference between a systematic and a non-systematic (intuitive) approach to fault diagnosis, and when might each be used?

A systematic approach follows a logical, structured procedure (e.g. half-split, six-step) and is reliable for complex or unfamiliar faults, giving traceable results. A non-systematic/intuitive approach uses experience to go straight to a likely cause and is fast for familiar, recurring faults — but risks missing the real cause on unfamiliar problems.

What does it mean to 'calibrate' a measuring instrument, and what is a calibration standard?

Calibration is comparing an instrument's readings against a known reference (standard) of higher accuracy, and adjusting or documenting any error, to ensure measurements are traceable and within acceptable limits. A calibration standard is the reference of known value (e.g. gauge blocks, a reference voltage, a master gauge) whose accuracy is traceable to a national/international standard.

What is meant by 'traceability' in measurement and calibration?

Traceability is an unbroken chain of comparisons linking an instrument's measurement back to a recognised national or international standard (e.g. NPL/SI units), each with stated uncertainties. It ensures measurements made by different people, places, and instruments are consistent and can be trusted/compared.

When using a multimeter, why must it be set to current mode and connected in series, but voltage mode and connected in parallel?

Current (ammeter) must carry the circuit current, so it is placed in series and has very low internal resistance. Voltage (voltmeter) measures potential difference across a component, so it is placed in parallel and has very high internal resistance to avoid drawing current and disturbing the circuit. Connecting an ammeter in parallel can cause a short-circuit and damage.

What is the difference between calibration and verification of test equipment?

Calibration compares the instrument against a reference standard and quantifies/adjusts its error across its range, establishing traceability. Verification is a check that the instrument still meets a required specification or gives an acceptable reading at a point (a pass/fail confirmation). Calibration is the fuller process; verification confirms ongoing fitness for use between calibrations.

What factors should a technician consider when selecting an appropriate method or process for a task?

Key factors: the required accuracy/tolerance and surface finish, material properties, quantity/batch size, available equipment and skills, cost and time, health-and-safety implications, and quality requirements. The best method balances technical suitability against cost, time, and safety rather than capability alone.

When selecting a measuring instrument, what general rule relates the instrument's resolution to the tolerance being measured?

As a general rule (the '10:1' or gauge-maker's rule), the instrument's resolution/uncertainty should be about one-tenth (or finer) of the tolerance being measured, so the measurement error is small relative to the permitted variation. For example, a tolerance of $\pm 0.1$ mm calls for an instrument resolving about $0.01$ mm.

In structured engineering problem-solving, what are the main stages from problem to solution?

A typical sequence: (1) Define/clarify the problem and constraints; (2) Gather information and requirements; (3) Generate possible solutions (ideas/options); (4) Evaluate options against criteria (cost, feasibility, safety); (5) Select and plan the best solution; (6) Implement; (7) Test/evaluate the result and refine. This disciplined process avoids jumping to conclusions.

What is the difference between continuous improvement (Kaizen) and a one-off project improvement at technician level?

Continuous improvement (Kaizen) is the ongoing pursuit of many small, incremental, sustained improvements to processes by everyone involved, embedded as a routine culture. A one-off project improvement is a single, often larger, change implemented and then complete. Kaizen emphasises constant small gains and worker involvement rather than occasional big interventions.

Describe the PDCA cycle used in continuous improvement and what each letter stands for.

PDCA = Plan, Do, Check, Act (the Deming cycle). Plan: identify the improvement and plan the change. Do: implement the change on a small/trial scale. Check: measure and compare results against expectations. Act: if successful, standardise/roll out the change; if not, revise and repeat. It is an iterative loop driving continuous improvement.

In Lean/continuous improvement, what is 'waste' (Muda), and name three of the common types of waste.

Waste (Muda) is any activity that consumes resources but adds no value for the customer. Common types (the seven/eight wastes) include: overproduction, waiting, transport, over-processing, excess inventory, unnecessary motion, defects (and underutilised talent). Identifying and eliminating waste is central to Lean continuous improvement.

What is the purpose of '5S' in workplace continuous improvement and what do the 5 S's stand for?

5S organises the workplace to improve efficiency, safety, and quality. The five stages are: Sort (remove unneeded items), Set in order (a place for everything), Shine (clean/inspect), Standardise (consistent procedures), and Sustain (maintain the discipline). It provides a clean, orderly, efficient working environment as a foundation for further improvement.