Maharashtra HSC Multi-Skill General Engineering (NSQF) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Least count of vernier calliper

The smallest measurement a vernier calliper can read, found by dividing one main-scale division by the number of vernier divisions. A 1 mm main division with 50 vernier divisions gives 0.02 mm.

Micrometer least count

Screw pitch divided by the number of thimble divisions. A 0.5 mm pitch screw with a 50-division thimble reads to 0.01 mm, and the barrel plus thimble readings are added together.

Clearance versus interference fit

A clearance fit always leaves a gap between hole and shaft, allowing movement. An interference fit always gives an overlap, so the parts must be pressed or shrunk together and cannot slide.

Accuracy versus precision

Accuracy is how close a reading is to the true value. Precision is how closely repeated readings agree with each other, so a precise instrument can still be inaccurate if it is badly calibrated.

Ohm's law

The current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance, written V equals I times R for a constant temperature.

Three-phase star connection

In a balanced star connection the line current equals the phase current, and the line voltage is the square root of three times the phase voltage, that is 1.732 times phase voltage.

Transformer turns ratio

The ratio of primary to secondary voltage equals the ratio of primary to secondary turns, and also equals the inverse ratio of primary to secondary current for an ideal transformer.

Zener diode regulation

A Zener diode is operated in reverse breakdown, where its voltage stays nearly constant over a range of current. It is used in shunt to hold a steady output voltage.

Earthing purpose

Earthing connects exposed metal parts to the general mass of earth through low resistance, so a fault current flows and trips the protective device instead of electrifying the enclosure.

Annealing versus normalising

Annealing softens steel and relieves internal stress by heating and very slow cooling. Normalising heats similarly but cools in still air, giving a finer grain and somewhat higher strength.

Brass and bronze

Brass is an alloy of copper and zinc, while bronze is mainly copper with tin. Both resist corrosion and are used for bearings, bushes, valves, and decorative fittings.

Pattern draft allowance

A small taper given to vertical faces of a casting pattern so it can be withdrawn from the sand mould without damaging the mould walls. It is added to the pattern dimensions.

Lathe cutting speed

Cutting speed in metres per minute equals pi times diameter in millimetres times spindle speed in revolutions per minute, divided by one thousand. It guides the correct rpm choice.

Velocity ratio of machine

The distance moved by the effort divided by the distance moved by the load. Efficiency equals mechanical advantage divided by velocity ratio, expressed as a percentage.

Gear train velocity ratio

For a gear train, the velocity ratio equals the product of teeth on driven gears divided by the product of teeth on driving gears. A larger driven gear slows the output.

Four-stroke engine cycle

The cycle needs two crankshaft revolutions and four strokes: suction draws the charge, compression raises pressure, power follows ignition, and exhaust clears the cylinder.

Stress and strain

Stress is force divided by cross-sectional area, in newtons per square millimetre. Strain is change in length divided by original length and has no unit.

First-angle projection

The object is placed between the observer and the projection plane. The view seen from above is therefore drawn below the front view, and the left view appears on the right.

Isometric scale factor

In isometric projection every true length is multiplied by 0.816 so the axes foreshorten equally. Isometric drawing skips this reduction and uses full lengths along the axes.

Representative fraction

The ratio of drawing length to actual length, written as a fraction such as 1:50. A larger denominator means a smaller drawing of the same object.

Hidden line convention

Hidden edges are drawn as short dashes of equal length with small equal gaps. They show features not visible in that view and are omitted where a centre line replaces them.

Fire extinguisher classes

Class A solid fuels use water or foam, Class B liquids use foam or dry powder, and electrical fires need carbon dioxide or dry powder. Water must never be used on live electrical equipment.

Machine guard rule

Guards must be fitted and secure before a machine starts. No measuring, cleaning, or adjustment is done while parts rotate, and the emergency stop is tested each shift.

Tap drill size rule

For metric threads the tapping drill diameter is approximately the nominal diameter minus the pitch. An M10 thread with 1.5 mm pitch therefore needs about an 8.5 mm drill.

Preventive maintenance

Scheduled servicing carried out by time or running hours before a fault occurs. It includes lubrication, cleaning, adjustment, and replacement of worn parts at set intervals.

Break-even quantity

Fixed cost divided by contribution per unit, where contribution is selling price minus variable cost per unit. It is the output at which total revenue equals total cost.

Working capital

Current assets minus current liabilities. A positive figure shows that short-term assets can cover short-term obligations, which matters for day-to-day running of a small enterprise.

Active listening

Listening that involves full attention, no interruption, and paraphrasing the speaker's meaning back to confirm understanding, followed by clarifying questions where something is unclear.

Situation-task-action-result

A structure for answering interview questions: describe the situation, state your task, explain the action you took, and give the measurable result achieved.

Newton's second law

The acceleration of a body is proportional to the net force acting on it and inversely proportional to its mass, written force equals mass times acceleration in SI units.

Latent heat

The heat needed to change the state of a substance without changing its temperature, calculated as mass times specific latent heat. Melting and boiling each need their own latent heat.

Sine bar principle

A sine bar sets an angle using slip gauges under one roller. The sine of the angle equals the gauge height divided by the fixed distance between the two rollers.