Maharashtra HSC Workshop Science & Calculation key terms

The rate at which the workpiece surface moves past the cutting tool edge, usually expressed in metres per minute and calculated from tool or job diameter and spindle speed.

The rotational frequency of the machine spindle, expressed in revolutions per minute, chosen so that the resulting cutting speed suits the tool and material.

The distance the cutting tool advances along the workpiece per revolution or per minute, controlling chip thickness, surface finish and the time needed to complete a pass.

The time a cut takes, found by dividing the total tool travel by the feed per minute, with allowances added for approach, overtravel and idle movements.

The thickness of material removed in one pass, measured radially on a lathe and axially on a milling machine, affecting cutting force, power demand and tool life.

A gradual, uniform reduction in diameter or width along a workpiece, defined by the difference in diameters divided by the length over which that change occurs.

The angle between the tapered surface and the axis of the workpiece, obtained from the inverse tangent of half the taper ratio.

A precision measuring device with two rollers set a fixed distance apart, used with slip gauges to set or verify angles to a high degree of accuracy.

Hardened, lapped steel blocks of accurately known thickness that are wrung together in combination to build up a required dimension for calibration or angle setting.

A measuring instrument with a main scale and a sliding vernier scale, used to read outside, inside and depth dimensions to a resolution typically of 0.02 mm.

A precision measuring instrument using a calibrated screw and thimble to measure small dimensions, commonly reading to 0.01 mm with a stated range of measurement.

The smallest measurement difference an instrument can display or distinguish, calculated from the value of one main-scale division divided by the number of vernier divisions.

The axial distance between corresponding points on adjacent thread turns or gear teeth, measured along the axis or pitch circle and used in feed and lead calculations.

The threaded shaft on a lathe or similar machine that drives the carriage, whose pitch determines how far the tool moves per spindle revolution during thread cutting.

The ratio of the number of teeth on a driven gear to that on the driving gear, setting the relationship between their speeds and torques in a transmission.

A gear design parameter equal to the pitch circle diameter divided by the number of teeth, expressed in millimetres and used to size metric gear teeth.

The diameter of the imaginary circle on which gear teeth roll without slipping, equal to the module multiplied by the number of teeth for a standard metric gear.

The mass of a substance per unit volume, commonly in kilograms per cubic metre or grams per cubic centimetre, used to convert a measured volume into an estimated mass.

The ratio of a material's density to that of water at a stated temperature, a dimensionless number convenient for quick workshop comparisons of materials.

The quantity of matter in an object, measured in kilograms or grams, calculated in the workshop as volume multiplied by density for stock and material estimates.

The three-dimensional space occupied by an object, found for common workshop shapes such as cylinders, prisms and cones using standard geometric formulae.

The measure of a two-dimensional surface, calculated for rectangles, circles, triangles and their combinations to estimate material use, paint or coating quantity.

A proportion expressed as a number of parts per hundred, used in the workshop for allowances, shrinkage, waste, efficiency and composition of alloys.

The difference between a measured value and the true or nominal value, expressed as a percentage of the true value, used to judge measurement accuracy.

Changing a quantity from one unit to another, such as millimetres to metres or kilowatts to watts, keeping the physical value unchanged by using the correct factor.

The internationally agreed system of measurement based on the metre, kilogram, second, ampere, kelvin, mole and candela, with derived units such as the newton and watt.

The rate at which work is done or energy is transferred, measured in watts, and calculated in electrical contexts as voltage multiplied by current for a resistive load.

The energy used by a load over time, calculated as power in kilowatts multiplied by hours of operation, giving the kilowatt-hour figure billed or tracked.

The ratio of useful output to total input, expressed as a percentage, showing how much supplied energy or power is converted into the intended work.

A metallic material made by combining a base metal with other elements to improve properties such as strength, hardness, corrosion resistance or machinability.

A material's resistance to indentation, scratching or wear, measured on scales such as Brinell, Rockwell or Vickers and used to judge suitability for tooling.

The ability of a material to absorb energy and deform plastically before fracturing, important where parts must withstand shock or impact loading.

Working out the expected cost of a job before production by summing material, labour, machine time and overhead charges, often with a percentage allowance for profit.

The quantity of stock needed for a batch, calculated from the finished part volume or mass plus allowances for waste, cutting stock and rejection.

Indirect costs of running a workshop, such as rent, supervision, power and maintenance, that are allocated to jobs as a rate or percentage of direct cost.

A method of representing a three-dimensional object by separate two-dimensional views projected onto perpendicular planes, showing true shape and size without perspective distortion.

The permissible variation between the upper and lower limits of a dimension, allowing parts to be made within an acceptable range while remaining interchangeable.

Applying a suitable oil, grease or solid film between moving surfaces to reduce friction and wear, carry away heat and protect against corrosion.

A fluid's resistance to flow, determining how readily a lubricant forms a film at a given temperature and speed, and guiding oil grade selection.

Scheduled inspection, cleaning, adjustment and replacement carried out before failure occurs, aimed at reducing breakdowns and extending machine life.