Drilling,boring & reaming.pptx

Drilling, boring and reaming operations

1. DRILLING - BORING - REAMING

2. contents :- 1. Drilling Machine Introduction Drilling characteristics Types Operations on drilling machine Geometry of twisted drills 2 . Boring Machine Introduction Types Tools Defects 3 - Rea m ing Introduction Types

3. Drilling Drilling is a cutting process that uses a drill bit to cut or enlarge a hole of circular cross-section in solid materials. The drill bit is a rotary cutting tool. . The bit is pressed against the work piece and rotated at rates from hundreds to thousands of revolutions per minute. It is estimated that 75 % of all metal cutting material removed ,comes from drilling operation

4. Working Principle :- The rotating edge of the drill exerts a large force on the work piece and the hole is generated. The removal of metal in a drilling operation is by shearing and extrusion.

5. Drilling :-

6. Drilling Characteristics The chips must exit out of the hole created by the cutting. Chip exit can cause problems when chips are large and/or continuous. The drill can wander upon entrance and for deep holes. For deep holes in large work pieces, coolant may need to be delivered through the drill shaft to the cutting front.

7. Types :- 1. Sensitive Drilling Machine

8. Sensitive Drilling machine :- It is a small machine used for drilling small holes in light jobs. In this drilling machine, work piece is mounted on the table and drill is fed into the work by purely hand control. High rotating speed of the drill and hand feed are the major features of sensitive drilling machine. .As the operator senses the drilling action in the work piece, at any instant, it is called sensitive drilling machine A sensitive drilling machine consists of a horizontal tab le. Drills of diameter from 1.5 to 15.5 mm can be rotated in the spindle of sensitive drilling machine.

9. 2.Upright Drilling Machine :

10. Upright Drilling machine:- The upright drilling machine is larger and heavier than a sensitive drilling machine It is designed for handling medium sized work piece and is supplied with power feed arrangement this machine a large number of spindle speeds and feeds may be available for drilling different types of work Upright drilling machines are available in various sizes and with various drilling capacities (ranging up to 75 mm diameter drills).

11. 3. Radial Drilling Machine :

12. Radial Drilling machine :- A Radial drilling machine consists of a heavy, round vertical column supporting a horizontal arm that carries the drill head. The table of radial drilling machine may also be rotated through 360 deg. The maximum size of hole that the machine can drill is not more than 50 mm. Powerful drive motors are geared directly into the head of the machine and a wide range of power feeds are available as well as sensitive and geared manual feeds. It is used primarily for drilling medium to large and heavy work pieces.

13. 4.Gang type drilling machine :-

14. Gang Type Drilling machine :- In gang drilling machine, a number of single spindle drilling machine columns are placed side by side on a common base and have a common worktable. A series of operation may be performed on the job by shifting the work from one position to the other on the worktable. 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

15. 5. Multi spindle drilling machine : -

16. 5.Multi spindle drilling machine:- The multiple-spindle drilling machine is used to drill a number of holes in a job simultaneously and to reproduce the same pattern of holes in a number of identical pieces in a mass production work. The entire drilling head works repeatedly using the same jig for batch or lot production of a particular job.

17. Geometry of twist drills :-

18. Geometry parts of twisted drill :- Twist drill geometry and its nomenclature are shown above. twist drill has three principal parts ( i ) Drill point or dead center ( ii ) Body ( iii ) Shank. Drill axis is the longitudinal line . Drill point is the sharpened end of the drill body consisting of all that part which is shaped to produce lips, faces and chisel edge. Lip or cutting edge is the edge formed by the intersection of the flank and face Lip length is the minimum distance between the outer corner and the chisel-edge corner of the lip.

19. Parts of twisted drill :- Face is that portion of the flute surface adjacent to the lip on which the chip impinges as it is cut from the work. Chisel edge is the edge formed by the intersection of the flanks. Flank is that surface on a drill point which extends behind the lip to the following flute. Flutes are the grooves in the body of the drill, which provide lips, allow the removal ofchips, and permit cutting fluid to reach the lips. Flute length is the axial length from the extreme end of the point to the termination of the flutes at the shank end of the body.

20. Parts of twisted drill :- Body is that portion of the drill nomenclature, which extends from the extreme cutting end to the beginning of the shank. Shank is that portion of the drill by which it is held and driven, Heel is the edge formed by the intersection of the flute surface and the body clearance. Body clearance is that portion of the body surface reduced in diameter to provide diametric clearance. Core or web is the central portion of the drill situated between the roots of the flutesand extending from the point end towards the shank; the point end of the core forms the chisel edge. Lands are the cylindrically ground surfaces on the leading edges of the drill flutes..

21. Drilling Operations :- Drilling :-operation of making a circular hole by removing a volume of metal from the job by a rotating cutting tool called drill. Boring :-Process of enlarging a hole. Reaming :-Operation of finishing a drilled hole. Counter boring :-Operation of boring a second hole ,larger in diameter than the first, but concentric with it. Counter sinking :-Operation of producing an angular surface at the end of a hole. Spot facing:-Operation of machining a flat ,circular surface around a hole to provide a seat for a bolthead, nut or washer.

22. Drilling operations..

23. BORING :- Boring is a process of producing circular internal profiles on a hole made by drilling or another process. It uses single point cutting tool called a boring bar. The boring bar can be rotated, or the work part can be rotated. Machine tools which rotate the boring bar against a stationary work piece are called boring machines (also boring mills).

24. Boring Machines :- 1.Horizontal boring machine :- A horizontal boring machine or horizontal boring mill is a machine tool which bores holes in a horizontal direction. There are three main types — table, planer and floor. The table type is the most common and, as it is the most versatile, it is also known as the universal type. Used for drilling ,boring, and milling operations.

25. Vertical boring machine:-

26. Vertical boring machine :- A large type of boring machine in which a rotating work piece is fastened to a horizontal table, which resembles a four-jaw independent chuck with extra radial T slots, and the tool has a traverse motion. Cutting tools are stationary except for feed movements.

27. Boring defects :- 1. Poor surface finish Cutting speed too low, feed rate too high ,blunt tool , 2. chatter:- 1. Incorrect front clearance ,lack of rigidity in boring cracking :- Improperly applied coolant ,cutting speed too low Excessive tool wear :-

28. REAMING :- The process of enlarging the hole is called reaming. There are many different types of reamer and they may be designed for use as a hand tool or in a machine tool, such as a milling machine or drill press. TYPES :- 1.Straight reamer :- A straight reamer is used to make only a minor enlargement to a hole. The entry end of the reamer will have a slight taper, the length of which will depend on its type

29. Types :- Hand reamer :-A hand reamer has a longer taper or lead in at the front than a machine reamer. This is to compensate for the difficulty of starting a hole by hand power alone. It also allows the reamer to start straight and reduce the risk of breakage. The flutes may be straight or spiral. Machine reamer:-machine reamer only has a very slight lead in. Because the reamer and work piece are pre-aligned by the machine there is no risk of it wandering

30. T yp es : - 4.Shell reamer:- Shell reamers are designed for reaming bearing and other similar items. They are fluted almost their whole length. 5. Taper reamer :-A precision tapered reamer is used to make a tapered hole to later receive a tapered pin.

31. Reamers : -