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# Drilling

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### Drilling

1. 1. DRILLING OPERATION presented by group B
2. 2. Drilling .  Drilling is a machining operation for producing round holes in metallic and nonmetallic Materials.  The machine used for drilling is called drilling machine as shown in figure.
3. 3.  Tool which makes hole is called as drill bit.  Drill bit are the tools used to cut away fine shavings material of work piece in a rotational motion.  The most common drill used is the twist drill.
4. 4.  The drilling operation can also be accomplished in lathe, in which the drill is held in tailstock and the work is held by the chuck.
5. 5. CUTTING CONDITIONS IN DRILLING Cutting Speed (v):- It’s the peripheral speed of the drill v = *D*N where D = dia. of the drill in m N = Speed of rotation in rpm Feed Rate (f):- It’s the movement of drill along the axis (rpm) Depth of Cut (d):- The distance from the machined surface to the drill axis d = D / 2
6. 6. Material Removal Rate:- It’s the volume of material removed by the drill per unit time MRR = ( D2 / 4) * f * N mm3 / min Machining Time (T) :- It depends upon the length (l) of the hole to be drilled , to the Speed (N) and feed (f) of the drill t = L / f N min
7. 7. TYPES OF DRILL MACHINE 1. Portable drill machine. 2. Cordless drilling machine. 3. Hand drill machine. 4. Bench drilling machine or upright sensitive drill machine 5. Radial drilling machine 6. Gang drilling machine 7. Multiple drilling machine
8. 8. PORTABLE DRILL MACHINE  It is used in domestic work.  Its shape like a gun.  Holes of diameter is approx.3to12.7mm.
9. 9. A cordless drill is an electric drill which uses recharable batries.These drills are available with similar features to an AC mains- powered drill. They are available in the hammer drill configuration and most have a clutch, which aids in driving screws into various substrates while not damaging them Cordless drills
10. 10. Hand Drill
11. 11. HOW TO USE A HAND DRILL
12. 12. Bench drilling machine  These are light duty machines used in small workshops.  Also called Sensitive drilling machines because of its accurate and well balanced spindle. And bit is feed by hand.  Holes of diameter 1 mm to 15 mm.  Its spindle Rpm is approximately 800 to 1000.  The adjustment of the rpm is used by the help of step pulley’s
13. 13. BELT DRIVE SYSTEM
14. 14. Parts of drilling machine  Vertical main column  Base  Moving drill head  Work table  Electric motor  Variable speed gear box and spindle feed mechanism.
15. 15. Radial drilling machine  These are heavy duty and versatile drilling machine used to perform drilling operate on large and heavy work piece.  Holes up to 7.5 cm.  The range of speed of spindle 50 to 2800 rpm.
16. 16. Parts of radial drilling machine  Heavy base  Vertical column  Horizontal arm  Drilling head
17. 17. GANG DRILLING MACHINE The gang style drilling machine or gang drill press has several work heads positioned over a single table. This type of drill press is used when successive operations are to be done. For instance, the first head may be used to make hole. The second head may be used to boring . The third head may be used, along with a tapping head, to tap the hole. The fourth head may be used to reaming.
18. 18. GANG DRILLING MACHINE
19. 19. MULTIPLE SPINDLE DRILLING M/C The multiple spindle drilling machine is commonly referred to as a multi spindle drill press. This special purpose drill press has many spindles connected to one main work head . All of the spindles are fed into the work piece at the same time. This type of drilling machine is especially useful when you have a large number of parts with many holes located close together.
20. 20. MULTIPLE DRILLING MACHINE
21. 21. Typical Drilling Processes
22. 22. CENTREING  Also called center drilling, this operation drills a starting hole to accurately establish its location for subsequent drilling. The tool is called a center drill.
23. 23. REAMING OPERATION  A reamer enters the work piece axially and enlarges an existing hole to the diameter of the tool.  A reamer is a multi-point tool that has many flutes, which may be straight or in a helix.  Reaming removes a minimal amount of material and is often performed after drilling to obtain both a more accurate diameter and a smoother internal finish.
24. 24. Reaming operation
25. 25. COUTERSINKING OPERATION  A countersink tool enlarges the top portion of an existing hole to a cone-shaped opening.  Countersinking is performed after drilling to provide space for the head of a fastener, such as a screw, to sit flush with the work piece surface.  Common included angles for a countersink include 60, 82, 90, 100, 118, and 120 degrees.
26. 26. COUNTERSINKING OPERATION
27. 27. COUNTERBORING OPERATION  A counter bore tool enlarges the top portion of an existing hole to the diameter of the tool.  Counter boring is often performed after drilling to provide space for the head of a fastener, such as a bolt, to sit flush with the work piece surface.  The counter boring tool has a pilot on the end to guide it straight into the existing hole
28. 28. COUNTERBORING OPERATION
29. 29. SPOT FACING OPERATION • Spot facing is similar to milling. It is used to provide a flat machined • surface on the workpart in a localized area. • Spot facing is commonly done on castings where irregular surfaces are found. • Spot facing may be performed on a drill press with a counter bore of suitable size for the operation.
30. 30.  A proper size pilot must be used whenever this is done on the drill press.
31. 31. TAPING OPERATION  This operation is performed by a tap and is used to provide internal screw threads on an existing hole.
32. 32. Drill Bit  The twist drill or drill bit is made from High Speed Steel, tempered to give maximum hardness throughout the parallel cutting portion  Different helix angles are available for drilling a range of materials.
33. 33. Drill Bit Fit in chuck Fit direct into spindle
34. 34. Drill Bit Features
35. 35. • SHANK The shank is the end of a drill bit grasped by the chuck of a drill. The cutting edges of the drill bit contact the work piece, and are connected via the shaft with the shank, which fits into the chuck or sleeve.• FLUTE Flute is a groove on drill bit start from the shank to the end point • Tang Tang is flat surface on the upper side of drill bit used to release drill bit from the socket or sleeve
36. 36. • Recess or neck It is in between body and shank it is also called stamp portion from industry where the drill bit made and also mention drill bit size • Body The body consist of flute,margin,body clearance and web• Point Point is cone shaped end of drill bit which lip clearance heel and dead center • Web Web is most important part of drill bit it is the thickness of drill bit b/w flute.
37. 37. Drill Bit Features  The point of the drill is ground to an angle of 118 degrees  each side is ground back to give " relief " of about 12 degrees to each cutting edge as shown
38. 38. The nomenclature of the twist drill is shown
39. 39. Twist drills Helix types Standard quick helixslow The helix angle of the twist drill is established during manufacture.
40. 40. Helix types  Drills with a helix angle of 20° — known as slow-helix drills — are available with a point angle of 118° for cutting brass and bronze and with a point angle of 90° for cutting plastics materials.  Quick-helix drills, with a helix angle of 40° and a point angle of 100°, are suitable for drilling the softer materials such as aluminium alloys and copper  The standard helix angle is 30 degrees, which, together with a point angle of 118°, is suitable for drilling steel and cast iron.
41. 41. Types of drill bits Wood bits masonry steel
42. 42. Precautions for Drilling machine  Lubrication is important to remove heat and friction.  Machines should be cleaned after use  Chips should be removed using brush.  T-slots, grooves, spindles sleeves, belts, pulley should be cleaned.  Machines should be lightly oiled to prevent from rusting
43. 43. Safety precaution  Do not support the work piece by hand – use work holding device.  Use brush to clean the chip  No adjustments while the machine is operating  Ensure for the cutting tools running straight before starting the operation.  Never place tools on the drilling table  Avoid loose clothing and protect the eyes.  Ease the feed if drill bit breaks inside the work piece.
44. 44. REFERENCES  Fundamental of modern manufacturing material processes and system by mikell p.groover  Wikipedia searches.  Slides from different universties.  Work-shop practice MT-236 by MOHAMMAD GYAAS.