engineering mechanic.pdf

Thermal Abrasive Waterjet Cutting Fundamental Manufacturing Processes Study Guide, DV13PUB1 - 1 - Training Objectives After watching the program and reviewing this printed material, the viewer will gain knowledge and understanding of the primary thermal cutting and waterjet cutting processes and the operational aspects of each. ? the basis for specific process selection is detailed ? the oxy-fuel gas process is presented ? plasma and laser cutting applications are explained ? abrasive waterjet cutting is examined Thermal and Waterjet Cutting The four most commonly used non-contact methods of metalcutting are oxy-fuel gas, plasma, laser, and abrasive waterjet. The first three cutting processes are thermal in nature, while the waterjet method cuts by abrasive erosion. These four processes are primarily used to make precision external and interior cuts on flat sheet and plate material. These processes are also used to trim previously formed parts. The selection of the most efficient process for a specific application is based on several factors: ? the type of work material ? work thickness ? intricacy of the cut ? quality of cut ? the desired cutting speed ? metallurgical effects ? environmental concerns ? cost of system ? cost per foot, or meter of cut The advantages of these four non-contact cutting processes include not having to rely on perishable cutting tools to shape parts, or elaborate workholding methods and systems to clamp parts. These processes do, however, use consumable items such as torch tips, gases, and abrasive materials. The thermal processes and the oxy-fuel gas process in particular share two disadvantages. First, heat changes the structure of metal in a ‘heat-affected zone’ adjacent to the cut. This may degrade some metallurgical qualities at the cuts edge, requiring pre-treatment or trimming. Secondly, tolerances may be less accurate than a machined cut, except for laser cutting. The therma