Manufacturing enginnering

• Chiseling


  Cutting away excess metal with a chisel
• Chiseling


  1. Hold work piece in a vice

  2. Hold chisel firmly but lightly

  3. Strike hammer handle near end with force suited to metal

  4. Hold chisel at 60 degree angle
• Cutting angle of chisels

  • Aluminium: 30 degrees
  • Copper: 45 degrees
  • Brass: 50 degrees
  • Low Carbon Steel: 55 degrees
  • Cast Iron: 60-65 degrees
  • High Carbon Steel: 65 degrees
• Tang chisel


  Chisel with a tang on the end of the blade that fits inside the handle
• Socket chisel


  Chisel with a handle fitted in a socket which is part of the blade
• Types of chisels


  • Flat chisels
  • Cross cut or cape chisels
  • Diamond point chisels
  • Round nose chisels
• Flat chisels


  • Conventionally used for chipping, cutting thin sheet metal, removing rivet heads
  • Cutting angle approximately 60 degrees
  • Width of cutting edge 20-25mm, length 10-250mm
• Cross cut or cape chisels


  • Used to cut keyways, grooves and slots
  • Narrow cutting edge, 6-10mm wide
• Diamond point chisels


  • Used to cut into corners of slots, internal angles
  • Cutting edge shaped like a diamond
• Round nose chisels


  • Used to cut grooves
  • Cutting edge is semi circular
• Care of chisels and chipping

  1. Use safety goggles

  2. Check head of chisel and handle of hammer

  3. Chip away from your body

  4. Place chisel against work piece and strike with hammer

  5. Cut grooves along long surfaces with cross cut chisel before chipping

  6. Lubricate cutting edge for longer life and quicker cutting
• File

  Tool used for smoothing and shaping metal
• Parts of a file

  • Body
  • Teeth
• Classification of files


  • By effective length
  • By type of cut (single cut, double cut)
  • By grade of cut (super smooth, dead-smooth, smooth, second cut, bastard, rough)

  
• Single cut file


  File with teeth slanting in one direction
• Double cut file


  File with two sets of teeth, used with greater pressure
• File selection


  • Depends on type of metal, shape of piece, shape to be filed, and degree of accuracy required
  • Begin with bastard-cut file, finish with second-cut or smooth file
  • Use file of proper length for work

  
• Methods of filing


  1. Cross filing (rough filing): cross the stroke at short intervals

  2. Draw filing: hold file at both ends and push/pull sideways
• Tap


  Cutting tool used to cut internal threads
• Taps


  • Made from high quality tool steel, hardened and ground
  • 2, 3 or 4 flutes cut lengthwise to form cutting edges, provide chip clearance, and admit cutting fluid
  • Shank is square to allow use of tap wrench
• Metric tap


  Tap with thread size specified as M(metric), nominal diameter in mm, and pitch in mm
• Tap drill diameter


  • Major diameter - thread pitch
• Comparison of American and Metric thread sizes

  • American Standard Thread Size and Tap Drill Size
  • ISO Metric Thread Size and Tap Drill Size
• Orthogonal cutting


  Cutting with the tool edge perpendicular to the direction of cutting

  
• Oblique cutting


  General case of cutting where the tool edge is not perpendicular to the direction of cutting

  
• Terms used in metal cutting

  • Rake face (tool face)
  • Tool flank
  • Rake angle (rake)
  • Clearance angle (clearance)
• Rake + Clearance + Wedge angle


  • Sum is 90 degrees
• Practical cutting tools


  • Single point tools
  • Multi point tools
• Single point tool


  Rectangular section 'tool shank' with ground tool faces and flanks forming the cutting edge
• Multi point tool


  Series of two or more single point cutting tools attached to a common body, e.g. twist drill
• Materials


  Substances that make up the physical world, including metals, ceramics, polymers, and composites
• Materials Science


  Understanding of how materials behave and why they differ in properties, based on atomistic understanding allowed by quantum mechanics
• Materials Engineering

  Development of materials science to design materials and provide a knowledge base for engineering applications
• Classification of materials


  • Crystalline (Metals, Ceramics)
  • Amorphous (Glass, Polymers)
  • Type of Bonding
  • Molecular & crystal Structure
  • Physical & Mechanical properties
• Types of materials


  • Metals and alloys (Iron, steel, Cu, Al & its alloys)
  • Polymers (Plastics/ Rubber, Nylon, Polyethylene)
  • Ceramics & Glasses (Al2O3, MgO, SiO2, SiC, Si3N4)
  • Composites (Wood, Fiber glass)
• Metals


  Valence electrons are detached from atoms, and spread in an 'electron sea' that "glues" the ions together. Metals are usually strong, conduct electricity and heat well and are opaque to light (shiny if polished).
• Semiconductors


  Bonding is covalent (electrons are shared between atoms). Their electrical properties depend extremely strongly on minute proportions of contaminants. They are opaque to visible light but transparent to the infrared.
• Ceramics


  Atoms behave mostly like either positive or negative ions, and are bound by Coulomb forces between them. They are usually combinations of metals or semiconductors with oxygen, nitrogen or carbon (oxides, nitrides, and carbides).
• Polymers


  Bound by covalent forces and also by weak van der Waals forces, and usually based on H, C and other non-metallic elements. They decompose at moderate temperatures (100 – 400 C), and are lightweight.
• Composites


  Made of different materials in intimate contact to achieve specific properties.