Muhammad ZaroonUniversity of Central Punjab (UCP) Lahore

Mechanical Engineering

a machine for making holes with removal of chips. Drilling machines are used for drilling, boring, countersinking, reaming, and tapping.

Vertical drilling machines are the most widely used in metalworking

Drill machine (Introduction)

Drill Machine (Drill bit)

Cutting Diameter is the largest diameter measured across the top off the land behind the point.

Drill Bit (ELEMENTS)

Back Tapper The diameter reduces towardsthe shank to provide the clearanceAnd prevent the Friction and Heat

FLUTES AND TYPES

parabolic Conventional chip breaker

Provide greater space for the

chips to .

In industry most of the drills have

this type of construction.

Process where long chips are produce , tight flute radii helps to breakdown of chips

The axial length from the outer corners of the cutting lips to the extreme back end of the flutes

To form the cutting edge on the pointTo allow the chip to escapeTo cause the chip to curlTo permit the cutting fluid to reach the

cutting edges

Why we Create FLUTES

The part of drill body between the flutes is called Land.Increase land increase Tensional StrengthDecrease Land Chip width increases

HELIX ANGLEThe helix or rake angle is the angle formed by the leading edge of the land with a plane having the axis of the drill.

TYPESHELIX ANGLE

HIGH SPIRAL degree

REGULAR SPIRALdegree

SLOW SPIRALdegree

34 to 38 28 to 32 12 to 22

Fast spiral Drills Slow spiral Drills•Greater lifting power for chips•Used for deeper holes•Weaker in strength

•Lesser lifting Power for chips•Generally for shallow holes•Stronger in Strength

Effect of helix angle on performance ??