AG:8.1 OVERVIEW

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If we had an engine block, how would you manufacture it ?

When deciding how to produce a product there are a number of factors to consider,

- Product geometry, material, tolerances, weight, etc

- Available processes/machine tools/skills

- Available tools and fixtures

- Inventory

- etc

Requicha and Vandenbrande [1988] describe the process of process planning as,

"A process planner and a set-up planner (often the same person) examine a part's blueprint and consult various files and handbooks to produce a process plan. A plan contains process specifications and information on fixtures and clamping devices to be used, and on set-up of the workpiece on a machine tool. Set-up specifications are typically conveyed through annotated sketches or engineering drawings."

A process plan will vary from factory to factory, but there are some basic elements to be found on all. An example is shown below.

Obviously a process plan is important when there is a high product mix, because it lets us know were to send the parts, and what to do with them. In a high volume setting, a process plan lets us decide exactly how something will be made before equipment is bought or moved.

A Process Plan includes,

- Part routings (Indication of where to send finished parts)

- Bill of Materials (for each operation)

- Work Orders (A description of what operations to perform at a work station).

Every company uses process planning. In smaller companies the process planner may also be the craftsman who makes the product. In larger companies there may be large departments set aside to perform this function.

As the size of a company grows, and so do the possible methods for manufacturing, and process planning become more difficult.

A Diagram of the traditional Two-Stage Approach to Process Planning

Depending upon who defines process planning, it may, or may not include operation planning.

In their purest sense, the definitions are,

- Process Planning - Choosing the technological means whereby a feature(s) of a product will be manufactured (eg. drilling, milling, or casting). Also known as high level process planning.

- Operation Planning - Choosing the parameters of the operation which is used to create the feature(s). (eg. feeds, speeds). Also known as low level process planning.