Thermal and Other Methods of Material RemovalCompetencyThermal Methods of Material RemovalSlide 4Slide 5Slide 6Slide 7Slide 8Chapter 7 IT 208 1Thermal and Other Methods of Material RemovalChapter 7Chapter 7IT 2082Competency Describe the process of oxy-fuel cutting and laser cuttingChapter 7IT 2083Thermal Methods of Material RemovalHot Wire CuttingUsed to cut foamed thermoplastic material (Thermoplastic - Soften repeatedly when heated)Requires good ventilationCannot cut thermosetting polymers, insulation materials or polyurethane foam (Thermosetting -When hardened cannot melt again)Chapter 7IT 2084Thermal Methods of Material RemovalOxy-Fuel Gas Cutting•A cutting torch uses a circle of oxy-fuel jets to bring the material to its melting point then compressed oxygen is released in a center nozzle to “blow away” the molten metal.•Typical oxy-fuel is oxygen-acetylene or oxygen-hydrogen •It is a fast, inexpensive process that requires fairly little operator training. •Plates as thick as 12 inches may be cut•Industry often uses computer controlled machines with multiple cutting torches to produce multiple parts simultaneously.Chapter 7IT 2085Thermal Methods of Material RemovalLASER Cutting - source of energy is a light -Light Amplification by Stimulated Emission of Radiation•Uses a highly focused light source as energy•Removes metal by melting and then vaporizing the workpiece, gas blows liquid and vapor away•Reflectivity and thermal conductivity of materials are important (dull materials preferred)•A gas stream helps to clear the path for beam•Small holes with deep depth can be made the size of the laser beam (blind holes cannot be made to exact depth)•Never look into a laser – can cause major damage to retinaChapter 7IT 2086Thermal Methods of Material Removal•Advantages•Material savings from very narrow kerf•Minimum heat effected zone•Fine finishes on thin pieces•Cut complicated shapes•Can cut material of any hardness•Can produce short runs quickly and efficiently •Disadvantages•Cost of machine can be as high as $2 million and more•Cost of maintenance can be $4,000 per machine per monthChapter 7IT 2087Thermal Methods of Material RemovalWater Saw (Waterjet)•Water that has been filtered for minerals and debris is increased in pressure from 20,000 to 60,000 psi and forced through a small orifice (0.003” to 0.023”) to cut through materialElectron Beam Machining - high velocity electrons strike work piece causing heat and melt the work piece•Voltages of 50,000-200,000 V•Must be done in a vacuum or loss of power results •Makes cuts accurately on smaller size work piecesChapter 7IT 2088Thermal Methods of Material RemovalAdvantages Disadvantages Oxy-Acetylene Flame Fast; can be used on large cuts Rougher cut surfaceWorkpiece surfaceoxidized Electron Beam clean; good precision Expensive; requires vacuum Water Saw Good on hard materialsRelatively fast Expensive