Manufacturing Process II

Unit: 1 Drilling

According to WBSCTE revised syllabus of 2022

1.1 Basic concept on drilling and boring operations.
1.2 Classification of drilling machines.
1.3 Basic parts and their functions of pillar drilling machine & radial drilling machine.
1.4 Specifications of drilling machines.
1.5 Types of drills and reamers.
1.6 Twist drill nomenclature.
1.7 Drilling machine operations: Drilling, boring, reaming, counter boring, countersinking, chamfering, Spot facing, Trepanning and deep hole drilling.
1.8 Cutting parameters and machining time calculation in respect of drilling (simple numerical).

What is Drilling?

• The machining process in which a multipoint cutting tool is used to remove metal from the work piece, in the form of chips to make a circular shape hole (blind hole or, through hole) is called Drilling.

• It is the machining process (removing a volume of metal) of making circular hole in a work piece.

• The tool used is called a Drill Bit.

• The machine which drives the drill bit into the work piece is called Drill Machine.

Types of Drilling Machine

• Portable Drilling Machine

• Sensitive Drilling Machine

• Upright Drilling Machine

• Radial Drilling Machine

• Gang Drilling Machine

• Multiple Spindle Drilling Machine

• Automatic Drilling Machine

• Deep Hole Drilling Machine

Portable Drilling Machine

• Small

• Compact

• Used in any position

• AC and DC

• Up to 12mm drill bit

Sensitive Drilling Machine

• Small machine

• Light weight job

• Hand controlled feed

• Horizontal table with vertical column

• Up to 15 mm drill bit

• Can be bench mounted and floor mounted

Upright Drilling Machine

• Heavier and larger than sensitive drilling machine & more speed and feed options

• Medium size job

• Up to 75mm drill bit

• Table may rotate

Types of Upright Drilling Machine are -

• Round column or Pillar drilling machine

• Box column

Radial Drilling Machine

• Heavy round vertical column supporting a horizontal arm carries a drill head

• Arm can rotate and move up down

• Drill head can move horizontally at any position over the radial arm

• Medium to large work piece.

Gang Drilling Machine

• No of single spindle column are placed side by side

• Series of operations can be performed one after the another.

Multiple Spindle Drilling Machine

• No of holes can be produced at a time.

• It is used to reproduce the same pattern in a mass production work.

Automatic Drilling Machine

Deep Hole Drilling Machine

• Deep hole drilling machines are used for drilling holes whose depth exceed normal drill size.

• It operates at high speed and low feed generally.

• It can be either Horizontal or Vertical.

Working Principle of Drilling Machine Tool

• When the power is given to the motor, the spindle rotates, and thereby the stepped pulley attached to it also rotates. On the other end, one more stepped pulley is attached and that is inverted to increase or decrease the speed of the rotational motion.

• Now, a V-belt is placed in between the stepped pulleys so as to drive the power transmission. Here a V-belt is used instead of a flat belt, in order to increase the power efficiency.

• Now the drill bit also rotates which was placed in the chuck and which was in connection with the spindle. As the Pulleys rotates, the spindle also rotates which can rotate the drill bit.

• Now, by the rotation of hand-wheel, the spindle moves up and down in the vertical direction in order to give the necessary amount of feed to the work and this drill bit is used to make the holes on the component placed in the machine vice.