Semi-generative Approach

The semi-generative approach is an interim approach and it is still in its infancy. Emerson and Ham (1982), when they presented a semi-generative system titled ACAPS, stated that 'It must be said at this point that the purely generative CAPP system has yet to be developed. Until such time as a generative system emerges, much effort has gone into "semi-generative" CAPP systems. These serve to reduce user interaction through such features as standard operation sequences, decision tables and mathematical formulas. These schemes are not completely generative, but they can be extremely useful in terms of time and cost savings in the manufacturing environment'.

So far, under the assumption that no CA-generative process planning systems exist, the semi-generative approach, as a stand-alone process planning approach, is understandable. The term 'semi-generative' approach may be defined as combination of the generative and the variant approach, where a pre-process plan is developed and modified before the plan is utilized in a real production environment. It means that the decision logic, formulae, and technological algorithms as well as the geometry based coding scheme for translating physical features (such as features sizes and tolerances, locations and surface roughness, etc.) are built into the systems. At a first sight, the system working steps are the same as for the generative approach, but the final process plan has to be examined and errors corrected if it does not fit to the real production environment. It may be a good idea to break a generative system down in a generating planning stage and a modifying stage to correct the plans which may be in conflict with the specific production environment. Modifying is small compared with the variant approach. From a research point of view the semi-generative system may not be the desired direction, but it increases the system's competitiveness on the market. Industrial application of such current systems can

• Speed up automatic production,
• Reduce the process planners participation, and
• Ensure the quality of process plan.

Since it is a practical oriented system for industry, the semi-generative approach may be a good candidate during the transition period.