MILLING

1. MILLING

2. QUESTIONS. • What are the 2 main categories of milling. • Name the 3 categories of milling machine and state which is used in the workshop. • State clearly the difference between Horizontal & Vertical milling machines. • List the 4 types of column & knee type milling machine and explain how they differ • Sketch the machine and label 6 parts. • What are arbors. • List and give the use for (a) arbor mounted and (b) chuck mounted milling cutters.

3. What do you need to know ? • The types of machines and cutters… • The parts of each… • Different operations…(linked to cutters) • Workholding methods…

4. What is milling ? • Milling is a metal cutting process • The cutting tool rotates • The cutting tool has several cutting edges • The work is fed linearly against the cutter

5. Components Made by Milling

6. Cutting Process

7. 2 principal types of milling 1. Face Milling. 2. Peripheral (side) Milling.

8. Types of machine. 2 MAIN GROUPS OF MACHINE. • Horizontal spindle machines • Vertical spindle machines

9. Horizontal. Vertical.

10. Main parts of the machine. • The Base • The Column • The Knee • The Saddle • The Table • The Spindle • The Arbor • The Overarm

11. Milling Process i.e. How the cutters cut

12. Milling Processes . Milling is a metal removal process by means of using a rotating cutter having one or more cutting teeth Cutting action is carried out by feeding the workpiece against the rotating cutter. Thus, the spindle speed, the table feed, the depth of cut, and the rotating direction of the cutter become the main parameters of the process. Good results can only be achieved with a well balanced settings of these parameters.

13. In up cut milling, the cutter rotates in a direction opposite to the table feed. It is conventionally used in most milling operations because the backlash between the leadscrew and the nut of the machine table can be eliminated. Up Cut Milling

14. In down cut milling, the cutter rotates in the same direction as the table feed. This method is also known as Climb Milling can only be used on machines equipped with a backlash eliminator or on a CNC milling machine. This method, when properly treated, will require less power in feeding the table and give a better surface finish on the workpiece Down Cut Milling

15. Typical Milling Operations

16. Plain MillingPlain milling is the milling of a flat surface with the axis of the cutter parallel to the machining surface. It can be carried out either on a horizontal machine or a vertical machine

17. End MillingEnd Milling is the milling of a flat surface with the axis of the cutter perpendicular to the machining surface

18. Gang milling is a horizontal milling operation that utilises three or more milling cutters grouped together for the milling of a complex surface in one pass. Gang Milling

19. In straddle milling, a group of spacers is mounted in between two side and face milling cutters on the spindle arbor as shown. Straddle Milling

20. Cutting Tools

21. Arbour Mounted a. Slab Mills For heavy cutting of large and flat surfaces. Cutting Tools for Horizontal Milling

22. b. Side and Face Cutters This type of cutters has cutting edges on the periphery and sides of the teeth for cutting shoulders and slots.

23. c. Slitting Saws For cutting deep slots or for parting off.

24. Chuck Mounted a. End Mills Commonly used for facing, slotting and profile milling. Cutting tools for Vertical Milling

25. b. Rough Cut End Mills For rapid metal removal.

26. c. Slot Drills For producing pockets without drilling a hole before hand.

27. d. Face Milling Cutters For heavy cutting.

28. WORKHOLDING.

29. The milling machine vice is the most common type of work holding devise used on the milling machine Plain Milling Machine Vice

30. Swivel Base and Vice The plain milling machine vice is used for holding work which has parallel sides. The vice is bolted directly to the table using the T-slots in the machine table. The plain vice can be accompanied by a swivel base as shown below enabling the vice to be rotated to different angles.

31. For machining operations involving compound angles, a universal vice is commonly used The universal vice allows the operator to tilt the workpiece 90 degrees in the vertical plane as well as swivel it 360 degrees in the horizontal plane Universal Angle Milling Vice

32. Locate the part in the center of the vice. This equalizes the pressure on the vice jaws Holding the workpiece off center puts unequal pressure on the vice jaws.  This can cause the piece to loosen up. USING THE VICE

33. Keep the workpiece as low in the vice as possible Work that extends out of the vice has a greater chance of loosening up under cutting conditions.

34. V-Blocks • V-Blocks hold and support round work for milling or drilling

35. V-Blocks are typically clamped directly to the table • A V-Block and a strap clamp being used to clamp a round part to the table.

36. Angle Plates • An angle plate is an L shaped piece of Cast Iron or Steel that has tapped holes or slots to facilitate the clamping of the workpiece. • Angle plates are used when parts need to have machining operations performed at a 90 degree angle to the axis of the table.

37. Angle plate being used to machine the end of a long part.

38. Direct Mounting to the Table • Work that is too large or has an odd configuration is usually bolted directly to the table. This method of work holding takes the most ingenuity and expertise.

39. A variety of commercially available clamp sets are available for directly mounting workpieces

40. Parallels • Parallels are pieces of steel bar stock accurately machines so that the opposing sides are parallel to each other. • Parallels are provided in sets of two with identical dimensions.

41. Parallels are used in order to provide clearance under the work so the cutting tool does not damage the machine table or the vise base

42. Dividing Head • A dividing head is a tool that is used to divide a circle into equal divisions.

43. Indexing Plates Sector Arms Crank