ECCENTRIC AND STRAP – An eccentric is a disc having its axis of rotation out of its centre. It is equivalent to a crankpin which is so large in diameter that embraces the shaft to which it is attached and dispenses with arms. Converts rotary motion into reciprocating motion. EFFICIENCY – Ratio of the useful work performed…
DIRECT CONNECTED COMPRESSOR – A compressor in which the prime mover is attached direct to the compressor without any interposed transmission such as chain, belt etc. DISPLACEMENT OF COMPRESSOR – The volume displaced by the net area of the compressor piston. This is the capacity of an air compressor, usually expressed in cum per minute. DOUBLE ACTING…
CENTRIFUGAL COMPRESSOR – A compressor designed to deliver large quantities of air or gas at low pressure, moved by centrifugal force generated by a fast revolving rotor. CHARLE’S LAW – At constant pressure, the volume of a gas is proportional to its absolute temperature. At constant volume, the pressure is proportional to its absolute temperature. CLEARANCE VOLUME…
BOYLE’S LAW – At constant temperature, the absolute pressure of a gas varies inversely as its volume. BACK LOCKING – The steering gear is so constructed that it is easy to turn the vehicle by steering wheel, but it is difficult to turn the steering wheel by turning the front wheels. This back locking prevents the bumps…
ABSOLUTE HUMIDITY – Actual quantity of water vapour in the air, usually expressed as so many grains of moisture in a cubic foot of air. ABSOLUTE PRESSURE – Pressure measured from the true zero or point of no pressure. ADIABATIC COMPRESSION – Compression of air without receiving or giving up heat. AFTER COOLER – A type of surface heat…
A powder can be defined as a finely divided particulate solid. · Engineering powders include metals and ceramics. · The main purpose of powder testing is to ensure whether or not the powder is suitable for further processing. Principle characteristics of metal powders are 1. Chemical composition (purity) 2. Particle size and its distribution 3. Particle shape 4. Particle porosity 5….
A number of secondary and finishing operations can be applied after sintering, some of them are: · Sizing : cold pressing the sintered part to improve dimensional accuracy. · Coining : cold pressing to press details into its surface. · Impregnation : oil fills the pores of the part · Infiltration : pores are filled with a molten metal · Heat treating : annealing can be done for…
· Powder metallurgy is used to make parts from materials that are very difficult to machine. · When some machining is required on such parts, Presintering is done before actual sintering operation. · Compact is heated for a short time at a temperature below sintering temperature · Presintering removes lubricants and binders added to powders during blending operation. · After presintering, the part acquires sufficient strength…
Pressing the powders into desired part shape as closely as possible to final dimensions Powders are compacted using high pressure. · Degree of pressure required depends upon ü Required density of final product ü Ease with which powder particles will weld together. · Compacting processes are a) Die pressing b) Roll pressing c) Extrusion Die pressing ➢It consists of upper punch and lower punch as shown…
Blending : Mixing powder of the same chemical composition but different sizes Mixing : Combining powders of different chemistries · The blade continuously rotates and mixes the powder. · Wet or dry mixing is generally employed. · For wet mixing water or dry solvent is used to obtain better mixing. · Blending and mixing is necessary for · Addition of lubricants coats the powders and reduces…