1. DRILLING
Drilling is a metal cutting process carried out by a rotating cutting tool to make circular holes in solid materials.
Tool which makes hole is called as drill bit or twist drill.

2. Through Holes vs. Blind Holes
Through holes - drill exits the opposite side of work
Blind holes – drill does not exit work on opposite side
Two hole types: (a) through hole and (b) blind hole

3. A power operated machine tool which holds the drill in its spindle rotating at high speeds and when actuated move linearly against the work piece produces a hole.

4. Classification of Drilling Machines
Based on construction:
Portable, Sensitive, Radial, Up right, Gang,
b)Based on Feed:
Hand and Power driven

5. Sensitive Drilling Machine
Drill holes from 1.5 to 15mm

6. Up-Right Drilling Machine
Drill holes upto 50mm
Table can move vertically and radially

7. Radial Drilling Machine
It the largest and most versatile used fro drilling medium to large and heavy work pieces.

8. Gang Drilling Machine
In this almost single purpose and more productive machine a number (2 to 6) of spindles with drills
(of same or different size) in a row are made to produce number of holes progressively or simultaneously

9. Operations on Drilling Machine

10. Reaming
It is a process of smoothing the surface of drilled holes with a tool.
Tool is called as reamer.
Initially a hole is drilled slightly smaller in size.
Drill is replaced by reamer.
Speed is reduced to half that of the drilling.
Used to enlarge a hole

11. Boring
It is process carried on a drilling machine to increase the size of an already drilled hole.
Initially a hole is drilled to the nearest size and using a boring tool the size of the hole is increased.

12. Counter boring
This process involves increasing the size of a hole at only one end.
Cutting tool will have a small cylindrical portion called pilot.
Cutting speed = two-thirds of the drilling speed for the same hole.

13. Counter sinking
This is an operation of making the end of a hole into a conical shape.
Cutting speed = half of the cutting speed of drilling for same hole.
Special angled cone shaped enlargement at the end of the hole
Cutting edges at the end of conical surface.
Cone angles of 60°, 82°, 90°, 100°, 110°, 120

14. Spot facing
It is a finishing operation to produce flat round surface usually around a drilled hole, for proper seating of bolt head or nut.
It is done using a special spot facing tool.

15. Tapping For cutting internal thread Multi cutting edge tool.
Tapping is performed either by hand or by machine.
Minor dia of the thread is drilled and then tapping is done.

16. Accurate Hole-making Pilot (Center) Drill Drilling Boring Reaming
Sequence of Operations:
Pilot (Center) Drill
Drilling
Boring
Reaming

17. DRILL MATERIALS The two most common types are 1. HSS drill - Low cost
2. Carbide- tipped drills
- high production and in CNC machines
Other types are
Solid Carbide drill,
TiN coated drills, carbide coated masonry drills,

18. Tool Nomenclature

19. MILLING
Machining operation in which work is fed past a rotating tool with multiple cutting edges
Axis of tool rotation is perpendicular to feed direction
Usually creates a planar surface; other geometries possible either by cutter path or cutter shape
Other considerations and terms:
Milling is an interrupted cutting operation
Cutting tool called a milling cutter, cutting edges called "teeth"
Machine tool called a milling machine

20. Figure 22.23 (b) vertical knee‑and‑column milling machine
Vertical Mill
Figure (b) vertical knee‑and‑column milling machine

21. CNC Vertical Mill
Column
Head
Table
Saddle
Knee
Spindle Speed

22. CNC Vertical Mill: Axes & Tools
Spindle
Tool Holder
+ Z-axis
Cutter
Alternate Tools (in quick-change magazine)
+ X-axis
Air Vise
– Y-axis

23. Milling Parameters Illustrated
Two forms of milling: (a) peripheral milling, and (b) face milling

24. Horizontal and Vertical Spindle Column and Knee type Milling Machines
Fig : Schematic illustration of a horizontal-spindle column-and-knee type milling machine.
Fig : Schematic illustration of a vertical-spindle column-and-knee type milling machine.

25. Arbors
Fig : Mounting a milling cutter on an arbor for use on a horizontal milling machine.

26. Slab Milling
The basic form of peripheral milling in which the cutter width extends beyond the workpiece on both sides

27. Slab Milling Slab milling also called as peripheral milling
Cutters have straight or helical teeth resulting in orthogonal or oblique cutting action
Fig : (a) Conventional milling and climb milling (b) Slab milling operation, showing depth of cut , d, feed per tooth, f, chip depth of cut, tc, and workpiece speed, v. (c) cutter travel distance lc to reach full depth of cut.

28. Slotting
Width of cutter is less than workpiece width, creating a slot in the work

29. End Milling
Cutter diameter is less than work width, so a slot is cut into part

30. Fig:Some of the basic type milling cutters and milling operations.
Highly versatile machining operation
Multitooth tool that produces a number of chips in one revolution
Fig:Some of the basic type milling cutters and milling operations.

31. MILLING
Addition to producing various external or internal round profiles,cutting operations can produce many other parts with more complex shapes
Fig:Typical parts and shapes produced with the machining process

32. Milling parameters

33. Cutters for different types of Milling
Fig : Cutters for (a) Straddle Milling, (b) form milling, (c) slotting, and (d) slitting with a milling cutter.

34. Other Milling Operations and Cutters
Fig : (a) T-slot cutting with a milling cutter. (b) A shell mill.

35. Shaping Machine