1.2 MANUFACTURING PROCESSES
Before discussing the rules and planning strategy used, it is important to outline the manufacturing context they are used in.
1.2.1 Basic Factors Considered in Process Selection
There are a number of factors commonly considered when selecting processes. Some of these can be quickly listed, as below (not in order).
The priority of these factors vary depending upon the industry, and the product. The process selected also determines which of these factors are relevant.
1.2.2 Conceptual Process Groups
At present, processes are often described in loose terms. The classifications vary between applications, and therefore it is hard to develop a unified model of all manufacturing processes. A list of processing concepts is given which represents what the author feels is a reasonable division of some modern manufacturing processes. Each of these process groups is considered to be independent, and complementary.
• Molding - Forming amorphous material into a solid shape through the use of a form, or mold.
• Joining - Causing a permanent kinematic bonding between parts through some sort of connection on a molecular level.
• Assembly - A group of parts which form a new part through couplings, fasteners, screws, etc. An assembly requires no bonding.
• Cutting - Creating new parts by severing an existing part.
• Machining - Deliberate removal of material to develop a newer, smaller geometry.
• Finishing - Processes which have imperceptible effect on the geometry.
• Forming - An intentional deformation to produce a new geometry.
• Handling - The physical movement of parts between locations and orientations.
By grouping the processes in this way, they can be matched to geometric functions (eventually the Boolean equation templates will be used). A list is presented below that shows how various processes match the classifications above. While this is not complete, it does indicate the intention of the author. Please note that the classification items vary for each of the following process groups.
- Precision Molding (Investment Casting)
- The V-Process (Vacuum Casting)
- Cold pressure Welding of sheets and wires
- Hot Pressure Welding (Molten Metal)
- Hot Pressure Welding (Solid State)
This list is too long, but it is also far from complete. (See Chang , and Dieter  for more information on processes, and their limitations).
1.2.3 Process Data Parameters
Four common process selection parameters listed are Geometry, Material, Tool, and Machine. The machine specified will allow examination of factors like specific tolerances for a machine, horsepower of the machine, pressure of the machine, or other parameters of interest. The tool information will allow access to things such as tool material, tool geometry (including chip breakers, shape of tool, methods of fixation, etc.). Using this information along with workpart geometry and material, the machining process may be selected in terms of tolerance capabilities, time, and cost. Workpart geometry and material also give information about possible processes for the part. The Geometry of the feature (including dimensions, tolerances, and geometric form) to be produced will allow, or disallow a process as a candidate. The material can also be a design factor in selecting a process.
1.2.4 Manufacturing Materials and Process Groups
In some cases materials can determine a process. The list below shows some common processes and a couple of materials that they are suited to.
- Compacted Graphite Cast Iron
More information about processes, and materials is available in Dieter .