Milling and grinding machine

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

2. 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

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5. 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

6. 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

7. 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

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

9. 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

10. 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

11. 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

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

13. 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

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

15. 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

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

17. 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

18. 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

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

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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

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30. 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

31. 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

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33. 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

34. 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

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