Types of Drilling tools -LearnMech

Types of Drilling tools -LearnMech

Drilling tools

Different types of drills are properly used for various applications depending upon work material, tool material, depth and diameter of the holes.

Read More : Classification/Types Of Drilling Machine use In Mechanical Workshop

General purpose drills may be classified as:

According to material:

  1. High speed steel – most common.
  2. Cemented carbides.
  3. Without or with coating.
  4. In the form of brazed, clamped or solid.
Types of Drilling tools
Types of Drilling tools

According to size:

  • Large twist drills of diameter around 40 mm.
  • Micro drills of diameter 25 μm to 500 μm.
  • Medium range diameter ranges between 3 mm to 25 mm (most widely used).

According to number of flutes:

  • Two fluted – most common.
  • Single flute – e.g., gun drill (robust).
  • Three or four flutes – called slot drill.

According to helix angle of the flutes:

  1. Usual: 200 to 350 – most common.
  2. Large helix: 450 to 600 – suitable for deep holes and softer work materials.
  3. Small helix: for harder / stronger materials.
  4. Zero helix: spade drills for high production drilling micro-drilling and hard work materials.

According to length to diameter ratio:

  • Deep hole drill; e.g. crank shaft drill, gun drill etc.
  • General type: L/φ ≅ 6 to 10.
  • Small length: e.g. centre drill.

According to shank:

  • Straight shank – small size drill being held in drill chuck.
  • Taper shank – medium to large size drills being fitted into the spindle nose directly or through taper sockets and sleeves.

According to specific applications:

  1. Centre drill [Fig. 3.126 (a)] for small axial holes with 600 taper ends to hold the lathe centre.
  2. Step drill and sub land drill [Fig. 3.126 (b and c)] for small holes with 2 or 3 steps.
  3. Ejector drill for high speed drilling of large diameter holes.
  4. Taper drill for batch production.
  5. Trepanning tool [Fig. 3.126 (g)] for large holes in soft materials.

Sachin Thorat

Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.

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