The following examples of typical KBE applications demonstrate some of the considerable benefits to be gained from its use.

1) Lotus engineering. This used the integrated car engineer (ICE) system in the design of the Lotus Elise. ICE consists of a vehicle layout system, and modules to support the design of suspension, engines, power-train, wheel envelope and wipers [17].

2) The Boeing Commercial Airplane Group. This uses KBE as a tool to capture airplane knowledge to reduce the resources required for producing a design [18].

3) Jaguar cars. The company’s KBE group devised a system that reduced the time taken to design an inner bonnet from 8 weeks to 20 min [19].

2.2 Problem to solve in a CAPP system based on KBE

A stamping CAPP system should deal with all knowledge including geometry, non-geometry, engineers experience, rules and criteria, results of tests and numerical simulation, or even successful cases, because of the complexity of automobile body panels. The knowledge is involved in perse fields, such as metal forming technology, metal forming mechanics, modern design methodology, numer- ical simulation technology, and artificial intelligence. Accordingly, the CAPP system has to solve the problems with expression and application of all knowledge, and integration of all multidisciplinary design.

A CAPP system is essentially a set of instructions and guidelines on how to perform a complex procedure. It details the inpidual sub-tasks, how they should be carried out, in what order, and how the work should be doc- umented.  Furthermore,  as  system  requirements change,

new solutions tend to evolve from existing ones, so com- puter applications and their descendants can outlive the personnel involved in their initial development. All in all, a stamping CAPP system for automobile panels based on KBE should readily solve the following problems:

(1) Representations for all knowledge.

(2) Reasoning based on all this knowledge.

(3) Appropriate operation features acquired from stamping features and process rules incorporated with form- ability analysis.

(4) Process routes based on process sequencing and process combination knowledge.

(5) The control or management of process procedures for rapid response to all changes.

not only the foundation of intelligent CAPP for automobile panels, but also the integration of knowledge and methods, which combines the KBE system with the process plan- ning. With this model, KBE acts as a knowledge source to drive PCS, PIM, and LE, which makes process planning integrated and associative.

The PIM is a dynamic expanded information model, in which the information can be added and updated along with process planning. Using knowledge multi-expression format, the integrated information model of process plan- ning is built based on a feature model. For the hierarchy and framework of the features, semantic net and object- oriented methods are adopted to express knowledge and establish an information model in which process knowl- edge, e.g. database, parameter, rules, and experience, act as rules and attributes of the objects, and where whole product

  knowledge acts as a framework for relationships of objects.

3 Framework of a CAPP system

3.1 The integrated master model for a CAPP  system

To solve all corresponding problems mentioned above, the integrated master model is advanced at the system level to control and frame the CAPP system for automobile panels. It is a common concept and framework to generalize and spe- cialize the function, course control, process planning cir- cumstance, and activities involved in the development of an integrated and intelligent system into abstract groups, and to make them carry out all contents and processes. This model is suitable for knowledge expression and application, process controlling, information integration, change response, etc.