These rules are projected area, flatness, draw, draft, undercuts, dimensional stability, flash, machined surfaces and directional solidification。 Hui and Tan [15] proposed the sweep method to form the cavity and core。 The cavity and core are generated in a number of steps。 Sweeping the mould part in the draw direction generates a solid。 One end of the swept solid is subtracted from the first mould block。 The other end of the mould block is subtracted from the mould part。 The results of the above steps are subtracted with the part at the closed position to obtain the cavity and core。 Shin and Lee [16] proposed a method of core and cavity development so that the side cores and corresponding core and cavity plates can be generated。 This method is composed of 3 steps。 The designer determines the parting line that separates the product into 2 groups of faces。 Each group face has the parting surface attached to it。 Then external faces are added to each group face。 Shin added that a mould could be made up of many pieces in addition to the cavity, core and side cores。 Hui [17] studied the mouldability of an injection mould based on an external and internal undercut analysis only for polyhedral solids。 A blockage concept is presented to determine the main parting direction and a subpision technique is developed to evaluate the geometry of an undercut。 Chen et al。[18] introduced the concept of visibility maps (V-maps) of the pockets to determine the parting direction。 The method did not take into account internal undercuts。 Fu et al。 [19] and Nee et al。 [20] gave a new classification of undercuts according to the external loops and the internal loops of a moulded part。 The parting direction is then determined based on the proposed parting direction criteria considering the directions, location, number and volumes of undercut features。 Fu et al。 [21] proposed an approach to generate the parting surface by extruding the parting line edges and create the core/cavity block using the Boolean regularised difference operation (BRDO)。 A methodology that generates non-planar parting lines and surfaces is presented by Nee et al。 [22]。 Wong et al。 [23] proposed a method to determine the cutting plane of a complex shaped product。 Their method uses an algorithm that slices the product。 The parting line and surfaces formed by this method are planar。 Current research on automatic mould design is ongoing。 However, some methods can be quite theoretical and the mould design can have a complicated product geometry。 Most mould development activities involve a high level of skill, a wide variety of design expertise and knowledge。 Due to the fact that automatic mould development is still far beyond the current technology, it is more reasonable to provide intelligent rules or guidelines that prevent the design from conflicting with design constraints。 These rules also provide interactive tools in the detailed mould design environment。 This paper presents an interactive knowledgebased injection mould design system (IKB-MOULD)。 This system integrates the initial mould design and detailed mould design with both knowledge base and interactive commercial CAD/CAM software。 The next section of this paper outlines an analysis of the injection mould design process based on the mould designer's point of view。 A later section introduces the basic structure of our IKB-MOULD for injection mould design。 A case study of the injection mould design for a plastic product in IKB-MOULD is then presented。 The conclusion and future work is located in the last section。

2 The injection mould design process requirement analysis 

An injection mould design is composed of two steps: the initial design and the detailed design。 The initial design is composed of decisions made at the early stage of the mould design, such as the type of mould configuration, the number of cavities, the type of runner, the type of gate and the type of mould base。 The detailed design is composed of the insert (core/cavity) design, the ejection system design, the cooling and venting component design, the assembly analysis and the final drafting。