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Mechanical Engineering
Alokesh Pramanik

Definitions: Inventory Control: Manufacturing logistics: Manufacturing engineering: The organization of a factory so that products are fabricated and assembled to the assembled design, having specified tolerances etc, at the required rate, from appropriate materials, at the least cost on the equipment available. Mass production: When production volume gets high, especially in an assembly line. Results in a very high production rate where specialised equipment is used and the entire plant is often designed exclusively to increase production. Product Design: Turning: Process of machining external cylindrical and conical surfaces. Usually performed on a lathe where the workpiece is rotated and a single-point cutting tool is fed longitudinally into the workpiece then travels parallel to the axis of rotation, reducing the diameter by the depth of cut. Milling: Basic machining process by which a surface is generated by progressive chip removal. The workpiece is fed into a rotating cutting tool, often a multiple-tooth cutting tool to increase the material removal rate. Often good for mass-production work as a single pass of the cutting tool is often enough and results in a good surface finish. Arc Welding: Uses a carbon rod and the metal workpiece as two electrodes which an arc of energy is conducted between to create concentrated heat sources at temperatures approaching 4000⁰C. A filler metal is independently fed into the arc from the rod which replaces the carbon rod as the upper electrode and as it melts in the arc supplies the filler metal to complete the weld. Drilling: Basic machining process making up 25% of all processes which is unexpectedly complex. Most operations done with a twist drill with two cutting edges at the end of a relatively flexible tool. Planing operation: Sand casting: Most common and versatile casting process, makes up 90% of casting activities. Granular refractory material (silica, zircon, olivine or chromite sand) is mixed with small amounts of clay or water then packed around a pattern. Because the grains can pack into thin sections and can be economically used in large quantities, large sizes and great details can be used for this method. Grinding: Abrasive machining is a material removal process that involves the interaction of abrasive grits with the workpiece at high cutting speeds and shallow penetration depths. Sawing Cluster mill: Uses backup rolls to support the smaller work rolls. Used in the hot rolling of wide plate and sheets and always used for rolling foil as the smaller thickness requires small-diameter rolls. Several layers of foil are often rolled together (pack rolling) the simulate a thicker input material while still receiving a smaller roll. Continuous rolling mill: When the volume of a product justifies the investment, rolling may be performed on a continuous or tandem rolling mill. The slabs are heated and fed through a series of non-reversing rolling mill stands. This often consists of a roughing train of around 4 four-high mill stands and a finishing train of 6 or 7 additional four-high stands. Four-high mill: Similar to a cluster mill, a four-high mill uses backup rolls to support the smaller rolls which are used to create a much thinner final product. Two-high mill: two-high non-reversing mill is the simplest design but the material can only pass through the mill in one direction. A two-high reversing mill permits back and forth rolling but the rolls must be stopped, reversed and brought back to rolling speed between each pass. Three-high mill: Eliminates the need for roll reversal however requires some form of elevator on each side of the mill to raise or lower the material and mechanical manipulators to turn or shift the product between passes. Investment Casting: offers almost unlimited freedom in complexity of shapes and the types of materials that can be cast, (wax model, coated in ceramic and melted out) GO gauge Green Mold Casting flask CNC Functions: M30 Start spindle clockwise Spindle off Cutting fluid on Cutting fluid off End of program Miscellaneous: Change in diameter of the workpiece 1 x depth of cur 2 x depth of cut 1 x feed 2 x feed Basic metal cutting model Calculations: Revolutions/min =diameter, speed Removal rate = speed, feed, depth Clearance, min and max Short Answer: Name four ways in which a work-piece can be held in a lathe:  Three-jaw self-centring chucks are used for work that has a round or hexagonal cross- section. The jaws are moved inward or outward simultaneously by the rotation of a spiral cam. The chucks will provide automatic centring.  Four-jaw independent chuck: each jaw can be moved inward and outward independently of the others, thus it can be used to support a wide variety of shapes. Undue pressure on one jaw also does not destroy the accuracy of the chuck, therefore it can be used for heavy work.  Combination four-jaw chucks: available in which each jaw can be moved either independently or simultaneously.  Lathe Centres: Used for workpiece that are relatively long in comparison to their diameter. Two lathe centres are used, one in the spindle hole and the other in the hold in the tailstock quill; two types are used: dead and live centres.  Mandrels: Workpieces that must be machined on both ends or are disk shaped are often mounted on mandrels for turning between centres. Three common types include plain solid mandrels, gang mandrels and cone mandrels.  Collets
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