Safe Use of Punches in Engineering

Safe Use of Punches

• Safe use of punches depends on hitting them squarely and keeping their heads free of burrs that lead to mushrooming.
• Mushrooming occurs when a punch shank has been continuously hammered, causing the shank end to deform into a mushroom shape.
• The mushroom shape should be removed and returned to its original crowned shape using a bench grinder to minimize the chance of the punch splitting or chipping.

Punches

• Prick punches are small, sharp-pointed punches used to transfer dimensions and locations onto sheet metal for drilling.
• Prick punches should never be used to drive a pin or rivet from a hole, as they can scar the material and have relatively delicate points.
• Letter and figure punches are made of hardened and tempered steel and are used to stamp identifying symbols, letters, or numbers on work.
• All working edges of punches should be kept sharp, and all mushroomed material should be ground off the shank end to prevent eye injury.

Holding Tools

• Pliers are a group of tools that have a pair of legs joined by a pivot, hinge, or fulcrum pin.
• Pliers can have three types of joints: fixed, toggle or compound, and slip.
• Pliers are made of high-carbon tool steel or alloy steel, are classified by type and length, and are provided with handles shaped to give an efficient grip.

Specific Types of Pliers

• Multi-grips pliers are used to tighten the packing gland nut around a water pump shaft and have several curved grooves that make up a series of interlocking joints.
• Needle nose pliers are used in aviation maintenance and are handy for electrical and electronic work due to their small size and ability to grip and hold small components and wires.
• Circlip pliers are used for fitting and removing circlips in assembly and maintenance work.

Chisels

• Cold chisels are made from square or octagonal stock and have a flat cutting edge ground to an angle of approximately 70°.
• The cutting edge of a flat chisel is slightly wider than the shank and is ground slightly convex to reduce stresses transmitted to the sides of the cutting edge.

Files

• Files are cutting tools that have a large number of cutting edges or points rather than a single cutting edge.
• Files are pushed across a material by hand, and as they move, the teeth act like small chisels, removing small chips of material.
• Files are generally manufactured from high-carbon steel and are available in a variety of lengths, sections, cuts, and grades to suit almost every requirement.

Parts of a File

• The parts of a file include the tang, heel, faces, edges, point, and back.
• A safe edge is an edge on which no teeth are cut, permitting a corner to be cleaned out without damage to adjacent faces.

File Characteristics

• The rate of cutting and the finish given to the work are mainly determined by the depth and spacing of the file's cutting teeth.
• The grade of cut refers to how fine the file's teeth are, ranging from rough to smooth.
• The type of cut refers to the arrangement of cutting teeth, which is provided to give the most satisfactory results when working on different metals.

Category B1 and B2 Licences

• CASA B-07b: Maintenance Practices - General

Knowledge Levels

• Category A, B1, B2, and C Aircraft Maintenance Licence
• Basic knowledge levels for categories A, B1, and B2 are indicated by knowledge level indicators (1, 2, or 3) against each applicable subject
• Category C applicants must meet either the category B1 or category B2 basic knowledge levels

Knowledge Level Indicators

• Level 1:
  • Familiarity with basic elements of the subject
  • Ability to give a simple description of the whole subject using common words and examples
  • Ability to use typical terms
• Level 2:
  • General knowledge of theoretical and practical aspects of the subject
  • Ability to apply knowledge
  • Ability to understand theoretical fundamentals of the subject
  • Ability to give a general description of the subject using theoretical fundamentals and specific examples
  • Ability to use mathematical formulae in conjunction with physical laws
  • Ability to read and understand sketches, drawings, and schematics describing the subject
  • Ability to apply knowledge in a practical manner using detailed procedures
• Level 3:
  • Detailed knowledge of theoretical and practical aspects of the subject
  • Capacity to combine and apply separate elements of knowledge in a logical and comprehensive manner
  • Ability to know the theory of the subject and interrelationships with other subjects
  • Ability to give a detailed description of the subject using theoretical fundamentals and specific examples
  • Ability to understand and use mathematical formulae related to the subject
  • Ability to read, understand, and prepare sketches, simple drawings, and schematics describing the subject
  • Ability to apply knowledge in a practical manner using manufacturer's instructions
  • Ability to interpret results from various sources and measurements and apply corrective action where appropriate

Standards of Workmanship

• Workmanship refers to the degree of skill with which a product is made or a job is done
• Factors affecting workmanship include:
  • The art of skill of a worker
  • The quality of the product
  • The product or result of the labour and skill of a worker
  • Attitudes of the AME, team, and organisation
  • Duty of care (self, others, and equipment)
  • Working done according to a standard

Tools

• Hammers:
  • Include different types and weights of hammers and mallets
  • Each type has a specific use
  • Importance of using hammers properly to avoid damage to aircraft components and injury to personnel
• Ball Pein Hammers:
  • Range in weight from 28 grams (1 oz) to 1-1.5 kg (2-3 lb)
  • One hammer face is flat, while the other is formed into the shape of a ball
  • Flat hammer face is used for working metal and driving, but should not be used to drive a nail
  • Ball end is used to peen over rivets in commercial sheet metal work
• Cross Pein:
  • Narrow cross pein helps gain access to limited working surfaces
• Letter and Figure Punches:
  • Used to stamp identifying symbols, letters, or numbers on work
  • Made of hardened and tempered steel
  • Caution: All working edges of punches should be kept sharp, and all mushroomed material should be ground off the shank end to prevent eye injury
• Pliers:
  • Include a group of tools with a pair of legs joined by a pivot, hinge, or fulcrum pin
  • Classified by type and length
  • Provided with handles shaped to give an efficient grip for the hand
  • Made with a great variety of jaw shapes designed for cutting, holding, gripping, pulling, pushing, twisting, or turning
• Multi-Grips:
  • Used to tighten the packing gland nut around a water pump shaft
  • Have several curved grooves that make up a series of interlocking joints
  • Length of handles allows a great deal of force to be applied to the jaws