Pancyprian Machine Elements T.S. (Practical) cheat sheet

First-angle projection (ISO-E, used in Cyprus/EU): the object sits between observer and plane, so the view from the front is placed below the front view, the left-side view goes on the right, and the top view goes underneath.

Third-angle projection (ISO-A, US): the plane sits between observer and object; top view above front view, right-side view to the right. The truncated-cone symbol distinguishes the two systems on the title block.

Line hierarchy: continuous thick for visible outlines, continuous thin for dimension and projection lines, dashed for hidden edges, chain thin for centre lines and pitch circles, continuous thin with zigzag for partial (break) views.

Scale notation is drawing:reality - 1:2 is half size, 2:1 is double size. Dimension text always states the true size regardless of scale.

Dimensioning rules per ISO 129: dimension lines parallel to the measured edge, extension lines touch the outline with a small gap, arrowheads at both ends, figures above the dimension line, mm implied without a unit symbol.

Never dimension the same feature twice (over-dimensioning) and never close a chain of dimensions around a machined profile; leave one link as a reference or omit it to avoid tolerance accumulation conflicts.

Section views: cutting-plane line with arrows shows viewing direction; hatching at 45° thin lines for one part, opposite or different spacing for adjacent parts; shafts, bolts, pins and ribs cut longitudinally are drawn unsectioned.

Thread callouts: M20×2.5 (coarse, pitch omitted in practice), M20×1.5 (fine), Tr40×7 (trapezoidal), G1/2 (BSP parallel), R1/2 (BSP taper). Left-hand threads add LH; tolerance class follows, e.g. M10-6g/6H.

Geometric tolerancing (ISO 1101) frames read left to right: symbol, tolerance zone value, datum letters. Flatness and straightness need no datum; perpendicularity, parallelism, position and run-out do.

ISO 286 designation: 40 H7 means basic size 40 mm, hole tolerance class H7. Uppercase letters = holes, lowercase = shafts. IT grades IT01–IT18; IT6–IT7 for grinding/boring, IT11–IT13 for rough turning.

Fundamental deviation fixes the letter (H hole lower deviation = 0; h shaft upper deviation = 0), the IT grade fixes the zone width. Hole-basis system (H) is the default; shaft-basis (h) is used for cold-drawn shafting and bearing seats.

Fit type from the sign of the clearance: positive clearance = clearance fit (H7/g6, H7/f7 sliding), zero-to-negative = transition (H7/k6, H7/js6 location), always negative = interference (H7/p6, H7/s6 press).

Clearance max = ES − ei; clearance min = EI − es. For interference fits, interference max = es − EI and interference min = ei − ES (using hole ES/EI and shaft es/ei).

Tolerance of a dimension = upper limit − lower limit. Convert deviations to limits by adding them to the basic size before computing fit values.

Surface texture Ra relates to IT grade roughly: IT5 ≈ Ra 0.1–0.2 µm, IT7 ≈ 0.8–1.6 µm, IT9 ≈ 3.2 µm, IT11 ≈ 6.3–12.5 µm. Specify the coarsest Ra that satisfies function to control cost.

Geometric tolerance values are chosen from ISO 2768 general tolerances when not individually specified; general tolerances (ISO 2768-mK) cover dimensions and straightness/flatness/perpendicularity/symmetry.

Maximum material condition (MMC) = largest shaft / smallest hole; least material condition (LMC) = smallest shaft / largest hole. Bonus tolerance is available only with MMC modifiers.

Temperature matters: steel expands ≈ 11.5 × 10⁻⁶ /K. A 100 mm steel part measured 5 K above 20 °C reads about 0.006 mm oversize - negligible for IT9, significant for IT5.

Plain carbon steels: S235/S275/S355 structural (yield in MPa), C45 medium carbon for shafts and gears, C60/C75 for springs and tools. Weldability and hardenability decrease as carbon rises above ~0.4 %.

Alloy steels: 42CrMo4 for high-strength shafts, 20MnCr5 and 16MnCr5 for case-hardening gears, 100Cr6 (AISI 52100) for bearing rings and balls, X210Cr12 / X153CrMoV12 for cold-work tooling.

Cast irons: grey GJL (EN-GJL-250) good damping and machinability, nodular GJS (EN-GJS-400-15, -500-7) for higher strength and ductility; not weldable in the ordinary sense.

Non-ferrous: AlSi alloys (EN AC-44200) for light housings, CuSn bronze for worm wheels and plain bearings, brass CuZn39Pb3 for free-machining fittings.

Hardening: heat to austenitising (C45 ≈ 820–860 °C), quench (water for plain carbon, oil for alloy), then temper immediately - untempered martensite is brittle. Tempering 150–200 °C gives tools hardness; 500–650 °C gives tough shaft hardness.

Case hardening (16MnCr5/20MnCr5): carburise at 900–930 °C to 0.6–1.0 mm case, quench, temper at 150–200 °C; gives hard wear surface with tough core for gears.

Nitriding (42CrMo4, nitriding steels): 500–550 °C in ammonia, no quench, case 0.2–0.5 mm, minimal distortion, high surface hardness and wear resistance; slower than carburising.

Induction/flame hardening: local surface hardening of medium-carbon steel (C45, 42CrMo4) for journals and gear teeth; depth controlled by frequency, followed by low-temperature tempering.

Surface finishing: anodising for aluminium (oxide layer, corrosion and wear), electroplating (Zn, Ni, Cr) for steel, hot-dip galvanising for structural steel, phosphating and black oxide for corrosion plus oil retention, shot peening for fatigue strength.

Vernier caliper resolution: main scale 1 mm, vernier 50 divisions → 0.02 mm; 20 divisions → 0.05 mm. Reading = main scale before zero + matching vernier line × resolution. Check zero before use.

Micrometer: 0.5 mm per spindle revolution, thimble 50 divisions → 0.01 mm; read sleeve (mm and half-mm) plus thimble. Use the ratchet to limit measuring force to ~5–10 N; check zero with the anvils closed.

Dial indicator and test indicator: 0.01 mm or 0.001 mm resolution; use for run-out, flatness and alignment. Magnetic base plus indicator is the standard tool for shaft and coupling alignment checks.

Bore measurement: inside micrometer, bore gauge (transfer type set by micrometer), or telescopic gauges. For a 3-point internal micrometer, read the same way as an outside micrometer.

Calibration: instruments are checked against gauge blocks (grade 0/1) at 20 °C; a gauge block set builds sizes by wringing. Calibration interval typically 12 months for workshop instruments.

Measurement uncertainty and rules: choose an instrument whose resolution is at least 1/10 of the tolerance band; Abbe error means calipers are less accurate than micrometers for the same size.

Feeler gauges for valve and bearing clearances, thread pitch gauges for identifying metric/Whitworth threads, radius gauges for fillets, and squares for checking perpendicularity.

Torque wrench: click or break-over type, set scale, tighten to the specified value, then release the spring after use. For torque-to-yield bolts, follow the angle method instead of a torque value.

Hand tools: use the correct size spanner/socket to avoid rounding; a torque multiplier or extension changes the applied torque; pull, do not push, a wrench, and never extend a spanner with a pipe.

Turning: cutting speed vc = π·D·n/1000 (m/min, D in mm, n in rpm). Feed f in mm/rev, depth of cut ap in mm. Roughing uses high f and ap with moderate vc; finishing uses low f and ap with high vc.

Turning operations: facing, straight turning, taper turning (compound rest or taper attachment), parting off (low speed, plenty of coolant, tool exactly on centre), threading (pitch set by gearbox or change gears, half-nut engaged on the same index).

Milling: cutter speed n = 1000·vc/(π·D). Feed per tooth fz, table feed vf = fz·z·n. Climb milling gives better finish on rigid machines with backlash eliminators; conventional milling is safer on older machines.

Drilling: use a centre punch and pilot drill for accuracy; speed roughly half that of turning for the same material; peck drilling for deep holes; tapping uses the tapping drill = nominal − pitch (e.g. M10×1.5 → 8.5 mm).

Grinding: surface and cylindrical grinding for IT5–IT7 and Ra 0.1–0.8 µm; dress the wheel to keep it sharp; use coolant to avoid burning; balance wheels before high-speed use.

Cutting tool materials: HSS for drills, taps and general turning; cemented carbide (P for steel, K for cast iron, M for stainless) for production; coated carbide and ceramic/CBN for hard turning; diamond for non-ferrous finishing.

Coolant functions: cooling, lubrication, chip flushing and corrosion protection. Water-soluble emulsions for general machining; neat oils for gear hobbing and difficult threading; dry machining for cast iron.

Machine safety: chuck key removed before starting, guards in place, no gloves near rotating parts, workpiece clamped rigidly, tool set on centre height, and stop the spindle before measuring.

Press fits: heat the housing (e.g. 80–120 °C) or cool the shaft (dry ice) to reduce interference for assembly; never hammer a bearing inner ring through the balls - press on the ring that carries the fit.

Screw threads: tighten in a star/cross pattern to the specified torque in stages; use thread-locking compound where specified; for critical joints, check bolt elongation or use a torque-angle method.

Keys and keyways: parallel key transmits torque by shear and bearing; check key fit (no rocking), file burrs, and use a gib-head key where axial removal is needed. Woodruff keys for light location.

Circlips and retaining rings: fit with the correct pliers, ensure the ring seats fully in the groove, and fit the sharp edge away from the load direction. Replace deformed rings.

Gear assembly: check backlash with a feeler gauge or dial indicator (typical 0.05–0.15 mm for small gears), check tooth contact pattern with marking compound, and set bearing preload per the manual.

Couplings: check parallel and angular misalignment with a dial indicator or laser alignment; correct soft foot first; re-check after bolt tightening and after the machine has run at temperature.

Dismantling: mark mating parts before separation, support shafts, use pullers on the inner ring, avoid heat on seals and plastic parts, and keep a parts layout for reassembly.

Adjustment: set bearing clearance/preload by shims or locknut; set belt tension by deflection (≈1 % of span for V-belts); set chain slack per manufacturer; verify free rotation by hand before power-on.

Deep-groove ball bearing designation: 6205 = 25 mm bore (bore code × 5 for 04–96), 6205-2RS double rubber seal, 6205-ZZ metal shield, C3 internal clearance. Suffix meanings must be read from the catalogue.

Bearing life: L10 = (C/P)^p × 10⁶ revolutions, p = 3 for ball, 10/3 for roller. C is the basic dynamic load rating, P the equivalent dynamic load. L10h = L10 × 10⁶/(60·n).

Bearing types: deep-groove ball (radial + light axial), angular contact (axial one direction, mount in pairs), cylindrical roller (high radial, no axial), spherical roller (misalignment), tapered roller (combined loads, adjustable), thrust bearings (axial only).

Seals: radial lip seal (rotary shaft seal) with the lip facing the medium to be retained; labyrinth seals for high speed; O-rings for static sealing; gland packing for valves and pumps; mechanical seals for pumps with hazardous or hot fluids.

Lubrication: grease for sealed bearings and low-speed applications (fill 1/3 of housing), oil for high speed and heat removal. Viscosity must suit speed and temperature; too much grease causes churning and overheating.

Maintenance: condition monitoring by vibration (ISO 10816 zones), temperature, oil analysis and noise; planned replacement based on L10h and inspection, not only on failure.

Bearing mounting: interference on the rotating ring (inner ring on shaft for rotating shaft), clearance fit on the stationary ring; never fit a bearing by pressing on the cage or seals; align housing and shaft before fitting.

Failure causes: fatigue spalling (normal end of life), brinelling from shock or wrong mounting, false brinelling from vibration at standstill, smearing from sliding, and contamination - read the failure pattern before replacing.

Belt drives: velocity ratio = D1/D2 = n2/n1. V-belt tension by deflection (≈16 mm per metre of span); check pulley alignment with a straight edge; replace matched sets, not single belts, on multi-belt drives.

Chain drives: pitch and number of teeth set the ratio; keep slack on the slack side, lubricate by drip or bath for higher speeds, and check sprocket wear (hook-shaped teeth) before replacing the chain.

Gear ratio = z2/z1 = n1/n2; module m = d/z; centre distance a = m(z1 + z2)/2. Helical gears add cos β in the transverse module. Backlash and contact pattern must be checked after assembly.

Couplings: rigid (flange) for aligned shafts, flexible (jaw, tyre, disc) for misalignment and shock, fluid couplings for soft start. Check alignment with dial indicators or laser; correct soft foot first.

Shaft alignment: parallel offset and angular misalignment must both be corrected. Thermal growth changes alignment between cold and running conditions - align cold with the specified offset.

Balancing: rotors above the limit speed need single- or two-plane balancing per ISO 1940; residual unbalance causes 1× running-speed vibration. Check for bent shafts and eccentric pulleys.

Clutches and brakes: check lining wear and adjust clearance; air-gap setting affects response; never adjust a brake to compensate for a worn lining - replace it.

Vibration diagnosis: 1× speed = unbalance or misalignment; 2× = misalignment or looseness; bearing frequencies (BPFO, BPFI) indicate race defects; gear mesh frequency indicates tooth problems.

Machine guarding: fixed guards for belts, pulleys and gears, interlocked guards for access doors, emergency stop within reach, and no operation with guards removed. Lockout/tagout before maintenance.

PPE: safety glasses for all machining, safety shoes in the workshop, hearing protection above 80 dB(A), gloves only for handling (never near rotating parts), and respiratory protection for dust and solvents.

Lifting: use rated slings and shackles, check SWL, keep the load low and balanced, never stand under a suspended load, and use two people or a spreader for long shafts.

Chemicals and waste: store oils, solvents and coolant in labelled containers; use the safety data sheet (SDS); segregate waste oil, metal swarf and used filters; never pour coolant to drain.

Fire and electricity: correct extinguisher class (CO₂ or powder for electrical, foam for oil), no damaged cables, earth/ground machines, and RCD protection on portable tools.

Quality control: first-off inspection, in-process checks, and final inspection against the drawing. Use control charts (X̄-R) and capability index Cpk ≥ 1.33 as a common target for critical dimensions.

Inspection planning: identify critical characteristics from the drawing, choose the instrument with adequate resolution, record results with the instrument ID and temperature, and keep traceability to calibration.

Non-conformance: quarantine the part, record the deviation, and route to the responsible engineer for disposition (rework, repair, concession, scrap). Corrective action addresses the root cause, not the symptom.

Housekeeping (5S): sort, set in order, shine, standardise, sustain - clear walkways, tool boards, chip removal, and spill control keep the workshop safe and auditable.

Belt drives: velocity ratio = D1/D2 = n2/n1. V-belt tension by deflection (≈16 mm per metre of span); check pulley alignment with a straight edge; replace matched sets, not single belts, on multi-belt drives.

Chain drives: pitch and number of teeth set the ratio; keep slack on the slack side, lubricate by drip or bath for higher speeds, and check sprocket wear (hook-shaped teeth) before replacing the chain.

Gear ratio = z2/z1 = n1/n2; module m = d/z; centre distance a = m(z1 + z2)/2. Helical gears add cos β in the transverse module. Backlash and contact pattern must be checked after assembly.

Couplings: rigid (flange) for aligned shafts, flexible (jaw, tyre, disc) for misalignment and shock, fluid couplings for soft start. Check alignment with dial indicators or laser; correct soft foot first.

Shaft alignment: parallel offset and angular misalignment must both be corrected. Thermal growth changes alignment between cold and running conditions - align cold with the specified offset.

Balancing: rotors above the limit speed need single- or two-plane balancing per ISO 1940; residual unbalance causes 1× running-speed vibration. Check for bent shafts and eccentric pulleys.

Clutches and brakes: check lining wear and adjust clearance; air-gap setting affects response; never adjust a brake to compensate for a worn lining - replace it.

Vibration diagnosis: 1× speed = unbalance or misalignment; 2× = misalignment or looseness; bearing frequencies (BPFO, BPFI) indicate race defects; gear mesh frequency indicates tooth problems.

Machine guarding: fixed guards for belts, pulleys and gears, interlocked guards for access doors, emergency stop within reach, and no operation with guards removed. Lockout/tagout before maintenance.

PPE: safety glasses for all machining, safety shoes in the workshop, hearing protection above 80 dB(A), gloves only for handling (never near rotating parts), and respiratory protection for dust and solvents.

Lifting: use rated slings and shackles, check SWL, keep the load low and balanced, never stand under a suspended load, and use two people or a spreader for long shafts.

Chemicals and waste: store oils, solvents and coolant in labelled containers; use the safety data sheet (SDS); segregate waste oil, metal swarf and used filters; never pour coolant to drain.

Fire and electricity: correct extinguisher class (CO₂ or powder for electrical, foam for oil), no damaged cables, earth/ground machines, and RCD protection on portable tools.

Quality control: first-off inspection, in-process checks, and final inspection against the drawing. Use control charts (X̄-R) and capability index Cpk ≥ 1.33 as a common target for critical dimensions.

Inspection planning: identify critical characteristics from the drawing, choose the instrument with adequate resolution, record results with the instrument ID and temperature, and keep traceability to calibration.

Non-conformance: quarantine the part, record the deviation, and route to the responsible engineer for disposition (rework, repair, concession, scrap). Corrective action addresses the root cause, not the symptom.

Housekeeping (5S): sort, set in order, shine, standardise, sustain - clear walkways, tool boards, chip removal, and spill control keep the workshop safe and auditable.

Belt drives: velocity ratio = D1/D2 = n2/n1. V-belt tension by deflection (≈16 mm per metre of span); check pulley alignment with a straight edge; replace matched sets, not single belts, on multi-belt drives.

Chain drives: pitch and number of teeth set the ratio; keep slack on the slack side, lubricate by drip or bath for higher speeds, and check sprocket wear (hook-shaped teeth) before replacing the chain.

Gear ratio = z2/z1 = n1/n2; module m = d/z; centre distance a = m(z1 + z2)/2. Helical gears add cos β in the transverse module. Backlash and contact pattern must be checked after assembly.

Couplings: rigid (flange) for aligned shafts, flexible (jaw, tyre, disc) for misalignment and shock, fluid couplings for soft start. Check alignment with dial indicators or laser; correct soft foot first.

Shaft alignment: parallel offset and angular misalignment must both be corrected. Thermal growth changes alignment between cold and running conditions - align cold with the specified offset.

Balancing: rotors above the limit speed need single- or two-plane balancing per ISO 1940; residual unbalance causes 1× running-speed vibration. Check for bent shafts and eccentric pulleys.

Clutches and brakes: check lining wear and adjust clearance; air-gap setting affects response; never adjust a brake to compensate for a worn lining - replace it.

Vibration diagnosis: 1× speed = unbalance or misalignment; 2× = misalignment or looseness; bearing frequencies (BPFO, BPFI) indicate race defects; gear mesh frequency indicates tooth problems.

Machine guarding: fixed guards for belts, pulleys and gears, interlocked guards for access doors, emergency stop within reach, and no operation with guards removed. Lockout/tagout before maintenance.

PPE: safety glasses for all machining, safety shoes in the workshop, hearing protection above 80 dB(A), gloves only for handling (never near rotating parts), and respiratory protection for dust and solvents.

Lifting: use rated slings and shackles, check SWL, keep the load low and balanced, never stand under a suspended load, and use two people or a spreader for long shafts.

Chemicals and waste: store oils, solvents and coolant in labelled containers; use the safety data sheet (SDS); segregate waste oil, metal swarf and used filters; never pour coolant to drain.

Fire and electricity: correct extinguisher class (CO₂ or powder for electrical, foam for oil), no damaged cables, earth/ground machines, and RCD protection on portable tools.

Quality control: first-off inspection, in-process checks, and final inspection against the drawing. Use control charts (X̄-R) and capability index Cpk ≥ 1.33 as a common target for critical dimensions.

Inspection planning: identify critical characteristics from the drawing, choose the instrument with adequate resolution, record results with the instrument ID and temperature, and keep traceability to calibration.

Non-conformance: quarantine the part, record the deviation, and route to the responsible engineer for disposition (rework, repair, concession, scrap). Corrective action addresses the root cause, not the symptom.

Housekeeping (5S): sort, set in order, shine, standardise, sustain - clear walkways, tool boards, chip removal, and spill control keep the workshop safe and auditable.