Maharashtra HSC Multi-Skill General Engineering (NSQF) key terms

Wearable gear such as goggles, gloves, helmets, and safety shoes that shields a worker from specific hazards. Selection depends on the task, so a fitter grinding metal needs eye protection while an electrician needs insulating gloves.

Physical barriers or interlocks fitted around rotating or moving parts of machines to keep hands and clothing away from pinch points. Guards must remain in place during operation and be checked before starting work.

A procedure in which an energy source is switched off, isolated, and locked, with a tag naming the person responsible, before maintenance begins. It prevents accidental restart of machines or unexpected energisation during repair work.

The three elements needed for combustion: fuel, oxygen, and heat. Removing any one stops the fire, which explains why a carbon dioxide extinguisher smothers flames by displacing oxygen and cooling the surface.

Letter groups that match extinguishers to fuel types: A for solid combustibles, B for flammable liquids, C for energised electrical equipment, and D for combustible metals. Using the wrong class can spread a fire rather than control it.

Injury caused when current passes through the human body, producing burns, muscle contraction, or heart rhythm disturbance. Severity rises with current, path through the body, and duration, so even low-voltage circuits can be lethal.

A deliberate low-resistance connection between exposed metalwork and the earth, giving fault current a safe return path. It makes protective devices trip quickly instead of letting metal casings stay live and shock the operator.

A protective device containing a metal element that melts and opens the circuit when current exceeds its rating. Once blown it must be replaced, and the replacement must carry the same current rating as the original.

A resettable switch that automatically opens a circuit on overload or short circuit and can be closed again after the fault is cleared. Miniature circuit breakers in distribution boards are common examples in workshops and homes.

The relationship stating that voltage equals current multiplied by resistance in a linear conductor. Rearranged, it lets you find current from supply voltage and load resistance, which is the basis of most workshop circuit calculations.

The rate at which electrical energy is converted, equal to voltage times current in a direct-current circuit. It is measured in watts and tells you how much heat or work a device produces per second.

Current whose direction reverses periodically, typically 50 times per second on the Indian supply. Transformers can change its voltage easily, which is why transmission and most workshop machines use it.

Current that flows in one constant direction, supplied by batteries, solar cells, or rectified AC. Electronic circuits and battery-operated tools rely on it because polarity stays fixed.

A drawing method that shows an object from several directions at right angles, using parallel lines of sight. Front, top, and side views are arranged in first-angle or third-angle layout to describe shape completely in two dimensions.

A layout convention in which the object sits between the observer and the plane, so the view appears on the far side of the object. The top view is placed below the front view, which is the standard in Indian drawing practice.

A layout convention in which the plane sits between the observer and the object, so each view appears on the same side as the observer. The top view is placed above the front view, a practice common in American drawings.

A pictorial drawing in which the three axes are spaced 120 degrees apart and lengths along them are drawn to true scale. It shows depth and shape in one image but is not used for dimensioning machined parts.

The ratio between a drawn length and the real length of the object. A 1:2 scale means the drawing is half size, and the ratio must be stated on the sheet so readers interpret dimensions correctly.

The permissible variation between the maximum and minimum limits of a dimension. It tells the machinist how much a feature may deviate from the nominal size while still allowing the part to assemble and function.

The system that pairs an allowable hole size range with a shaft size range to produce clearance, transition, or interference. Choosing the right fit decides whether parts slide freely, locate precisely, or lock together permanently.

The smallest measurement an instrument can read reliably. On a vernier calliper it is the difference between one main-scale division and one vernier division, often 0.02 mm, and it limits the precision claimed for a reading.

A measuring tool with a fixed main scale and a sliding vernier scale, used for outside, inside, and depth measurements. The vernier divisions let the user read fractions of a main-scale division accurately.

A precision instrument that uses a calibrated screw and thimble to measure small thicknesses and diameters, typically to 0.01 mm. Its frame, anvil, and spindle must be cleaned and the reading checked for zero error.

A systematic instrument fault in which the scale does not read zero when the jaws or anvils are fully closed. The error is recorded as positive or negative and applied as a correction to every measurement taken.

The fine-scale irregularity left on a machined surface by the cutting tool, expressed as an average deviation value. It affects friction, wear, and sealing, so drawings specify a limit that finishing operations must achieve.

A metal whose main constituent is iron, such as mild steel, cast iron, or alloy steel. Ferrous metals are magnetic and generally strong, but most rust unless protected by paint, oil, or coating.

A metal containing little or no iron, for example aluminium, copper, zinc, or brass. These resist corrosion well and conduct heat and electricity effectively, making them common in wiring, roofing, and lightweight parts.

A material made by melting two or more elements together, at least one being a metal, to obtain properties better than either alone. Steel, brass, and solder are everyday examples used in workshop production.

Controlled heating and cooling of a metal to change its internal structure and therefore its hardness, strength, or ductility. Processes such as annealing, hardening, and tempering are chosen according to the service the part must give.

A manufacturing process in which molten metal is poured into a mould cavity and allowed to solidify into the required shape. It suits complex or hollow parts that would be difficult or wasteful to cut from solid stock.

A permanent joining process that fuses two metal surfaces, usually with heat and sometimes filler metal or pressure. Joint strength depends on proper edge preparation, current setting, and cleanliness of the surfaces.

A joining method that melts a low-melting filler alloy between two cleaned metal surfaces without melting them. It is widely used in electrical work and sheet-metal seams where heat damage must stay low.

A machining operation in which a workpiece rotates against a stationary single-point tool to reduce diameter or face an end. It produces cylindrical surfaces and is the basis of most work done on a centre lathe.

The rate at which the workpiece surface moves past the cutting tool, usually quoted in metres per minute. Too high a speed burns the tool, too low a speed wastes time and spoils finish, so it is matched to material and tool.

Progressive loss of cutting-edge material through abrasion, heat, adhesion, or chipping during machining. It shows up as poor surface finish, rising forces, or dimensional drift, and the edge must be reground or replaced.

A machine element that supports a rotating shaft while allowing it to turn with minimum friction. Plain and rolling bearings carry radial or thrust loads and must be lubricated and aligned to give long service.

Introducing oil, grease, or another film between moving surfaces to reduce friction and remove heat. Correct grade and quantity prevent metal-to-metal contact, wear, and seizure in bearings, gears, and slides.

Scheduled inspection, cleaning, lubrication, and replacement carried out before a breakdown occurs. It reduces sudden stoppages and extends machine life compared with repairing equipment only after it fails.

The non-technical abilities employers expect alongside trade competence, including punctuality, teamwork, problem solving, and safe working habits. They are assessed in this qualification because they decide how effectively technical skill is applied at work.

The sequence of sender, message, channel, receiver, and feedback through which meaning is exchanged. Feedback confirms whether the message was understood, and noise or unclear wording breaks the chain at any stage.

Paying full attention to a speaker, noting both words and tone, and confirming understanding by summarising or questioning. It prevents instructions from being misapplied and is essential when receiving technical directions on site.

Identifying a need, organising resources, and accepting financial risk to start and run a venture. For a skilled technician it can mean a repair workshop or fabrication unit, requiring costing, marketing, and record keeping.

The sales volume at which total revenue equals total cost, so neither profit nor loss is made. Knowing it helps a small workshop set prices and judge how much work must be completed each month to survive.