Saws

• Sawing machines are important machine tools found in the machine shop
• Sawing machines are used in metalworking industries
• Types of sawing machines:

  • Reciprocating Saw
  • Band Saw
  • Circular Saw
• Two types of reciprocating saw:

  • Manual Hacksaw (hand operation)
  • Power Hacksaw (machine operation)
• Frame holds the hacksaw blade

  • Blades are responsible for cutting the workpiece
• Driving Head houses the main driving motor
• Coolant is used to dissipate heat due to friction
• Workpiece should be securely fastened in the vise
• For power hacksaw operation:

  • Use 130 rpm for mild steel
  • Use 90 rpm for tool steel (annealed)
• Sawing machines are important machine tools in the machine shop and are used in metalworking industries
• Types of sawing machines:

  • Reciprocating Saw
  • Band Saw
  • Circular Saw
• Two types of reciprocating saw:

  • Manual Hacksaw (hand operation)
  • Power Hacksaw (machine operation)
• Base is the lowermost and rigid part of the power saw machine, supporting all other elements
• Vise is used to hold the workpiece, with one fixed jaw and one moving jaw that can be swiveled to 45° on either side for clamping of workpieces of different sizes
• The movable jaw of the machine can be moved using a screw and nut arrangement
• Frame holds the hacksaw blade, responsible for cutting the workpiece
• Driving Head houses the main driving motor
• Coolant is used to dissipate heat due to friction
• Workpiece should be securely fastened in the vise
• For power hacksaw operation:

  • Use 130 rpm for mild steel
  • Use 90 rpm for tool steel (annealed)
• Base supports all other elements of the machine.
• Power hacksaw operation:

  • 60 rpm for mild steel (unannealed)
  • 90 rpm for tool steel (annealed)
  • 130 rpm for mild steel
• Band saw types:

  • Horizontal Band Saw
  • Vertical Band Saw
• Horizontal Band Saw:

  • Portable and hand-operated
• Vertical Band Saw:

  • Fixed on the foundation and machine-operated
• Band saw:

  • Employs the continuous action of an endless high-speed toothed blade
• Advantage of bandsaw over hacksaw:

  • Can cut irregular curves in metals
• Band saw controls:

  • Contains the switch to stop and resume the band saw operation
• Column in band saw:

  • Holds the head of the band saw
• Wheels in band saw:

  • Hold the band saw blade
• Workpiece Table in band saw:

  • Place where the workpiece is being cut
• Band saw bed:

  • Contains the lower wheel
  • Encloses the electric motor that drives the power band saw
• Circular sawing machine:

  • Also known as a cold sawing machine
  • Widely used for cut-off operation
• Circular saw blades:

  • Fairly large in diameter (250 to 400 mm) and operate at low speeds
• Main advantage of segmented teeth saw:

  • Disk can be made of less expensive steel
  • Teeth can be made up of high-speed steel or tungsten carbide
• During cutting operation with circular saw:

  • Saw is fed into the workpiece
  • Workpiece is positively clamped by mechanical or hydraulic means
• Circular saw cutting:

  • Cutting fluid is recommended for all metals except cast iron
• Circular saw blade:

  • Most important part of the circular saw
  • High-speed blades are coated with special nitrate treatment
• TPI (teeth per inch) calculation:

  • For 100 teeth in a blade and a circular blade diameter of 10, TPI is 3.67
  • For 120 teeth in a blade and a circular blade diameter of 10, TPI is 4
  • For 120 teeth in a blade and a circular blade diameter of 12, TPI is 3
  • For 180 teeth in a blade and a circular blade diameter of 10, TPI is 6
  • For 180 teeth in a blade and a circular blade diameter of 12, TPI is 5
  • For 200 teeth in a blade and a circular blade diameter of 10, TPI is 62
• Recommended blade speed for circular saw cutting:

  • Mild steel: 60-165 rpm
  • High carbon steel: 40-50 rpm