Milling and grinding machine www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Milling Milling is a metal cutting operation in which the work is progressively moved towards a rotating cutter for material removal process. Milling cutter is a multipoint cutting tool. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Milling machine A milling machine is a power operated machine tool in which the work piece is mounted on moving table is machined to various shapes when moved under a slow revolving cutter. Work piece is fed against a milling cutter. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Metal is removed in the form of chips by using a rotating multiple teeth milling cutter. Milling process is used for producing flat, contoured or helical surfaces for toothed gears, slots, etc. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Principle of milling The workpiece is mounted on the table can be fed either in the direction opposite to that of rotating cutter or in the same direction of the cutter. Classification Conventional or up milling. Climb or down milling. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Up milling Work piece advances against the rotating cutter. Chips are progressively thicker. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Down milling Work piece is fed in the same direction as that of the cutter tooth. Cutter enters top of the work piece and removes the chip that gets progressively thinner. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

comparison Up milling Down milling Work piece is fed in opposite direction of that of cutter. Chips are progressively thicker. Strong clamping is required since the cutting force is directed upwards and tends to lift the work piece. Poor surface finish and used for hard materials. Work piece is fed in same direction of that of cutter. Chips are progressively thinner. Strong clamping is not required since the cutting force is directed downwards and keeps work piece pressed to table. Good surface finish and used for soft materials. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

classification Milling machine can be broadly classified into : Plain or horizontal type of milling machine Vertical milling machine Universal milling machine Planer type milling machine Profile cutting milling machine www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Horizontal milling machine Base Column Arbor Knee Saddle Table Over arm YOKE www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Base – it is a hollow cast iron structure which forms the foundation of machine on which other parts are mounted. Column – houses main drive, transmission system, spindle. It is provided with vertical guide square or dovetail to accommodate knee. Knee – mounted on vertical guide of column moved up or down by an elevating screw. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS YOKE www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Saddle – mounted on knee which slides on it by operating cross feed handle. Table – mounted on top of saddle with a dovetail fit. Table slides perpendicular to the axis of saddle movement. Arbor – shaft which carries the cutter with its other end supported by yoke. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS YOKE www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Working Work piece is mounted directly on table using machine vice. Over arm – mounted on top of column. Supports the free end of arbor through yoke. Working Work piece is mounted directly on table using machine vice. Cutter of required shape and size are mounted over the arbor which is driven by spindle. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Feed in all 3 axis can be given by using knee elevating handle, cross slide handle, table movement handle. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS YOKE www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Vertical milling machine Base and column Spindle head www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Base and column – base is the foundation for the machine and column is the vertical part houses motor, transmission system. Spindle head – mounted on front face of the column at the top. It has a vertical spindle run by motor to which milling tool is fitted to end. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Working Work piece is mounted on table and cutter is mounted on vertical spindle. Feed is given by movement of saddle and table and also vertical movement of tool. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Milling process Plain milling End milling Slot milling Angular milling Form milling Straddle milling Gang milling www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Plain milling Process used to mill flat surfaces of the work piece. Milling cutter axis is parallel to the surface that is being milled. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

End milling Process of milling that is used to mill slots, pockets and keyways. Axis of milling cutter is perpendicular to the surface of the work piece. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Slot milling Cutter tool – “slot drill” Axis of spindle is horizontal or parallel to surface of work. To produce rectangular slots, T-slots, dovetail slots. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Angular milling To produce angular surfaces like dovetail, grooves and chamfers. Surface of slot is neither parallel nor perpendicular to the milling cutter axis. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Form milling This is a process used to machine special forms / contours consisting of curves. “form milling cutter” is the cutting tool which is shaped exactly to the contour to be milled. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Straddle milling Used to machine two parallel vertical surfaces at a single time. It has two cutters mounted parallel on the arbor separated by a calculated spacing. Also used to mill sides of hexagon. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Gang milling Gang milling is the term applied to an operation in which two or more milling cutters are used together on one arbor when cutting horizontal surfaces. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Specification of milling machine Clamping area – area of the work table where the jobs are to be clamped. Longitudinal movement (mm) – this is the distance along the X – axis by which the table along with the job moves longitudinally. www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

Speed – speed of the spindle rotation ( rpm) Transverse movement (mm) – distance along Y- axis by which the table travels in traverse direction. Speed – speed of the spindle rotation ( rpm) Power of milling spindle motor – power capacity of motor of spindle. (kW) www.bookspar.com | Website for Students | VTU NOTES | QUESTION PAPERS

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