Integrating data envelopment analysis and analytic hierarchy for the facility layout design in manufacturing systems

Additive manufacturing (AM) techniques such as selective laser melting (SLM) can enable the construction of injection moulding (IM) tools with conformal cooling channels that significantly improve performance through higher cooling uniformity and reduced cycle times. Design of IM cooling systems is typically achieved using commercial IM numerical modelling software originally developed for conventionally cooled mould designs. However, the accuracy of IM modelling software in predicting the performance of SLM manufactured tools with conformal cooling, across a range of moulding materials and processing conditions, has not been thoroughly evaluated in the literature. Furthermore, the SLM manufacturability and mechanical properties of tool steels typically applied in IM, such as AISI H13, are not well documented. This work addresses these deficiencies through the following: quantification of SLM H13 material properties, in particular fatigue strength which has not been previously reported; design and manufacture of a mould tool with easily exchangeable conventionally and conformally cooled inserts; and subsequent experimental validation of IM simulation software predictions under a range conditions. Result of mechanical testing showed SLM H13 parts to offer lower mechanical properties in the as-built condition compared to conventional materials; however, these increased substantially following residual stress reduction with heat treatment. Evaluation of the temperature prediction accuracy of IM numerical models showed generally high accuracy for conformally cooled SLM tools, although marginally lower when compared to conventionally cooled moulds. The outcomes of this work offer designers typical material property data for SLM manufactured H13 tooling, as well as an indication of the expected prediction accuracy of current commercial IM simulation software when applied to conformally cooled SLM tooling.

Numerical and experimental evaluation of a conformally cooled H13 steel injection mould manufactured with selective laser melting

With widely used concurrent and collaborative engineering technologies, the validity and consistency of product information become important. In order to establish the state of the art, this paper reviews emerging concurrent and collaborative engineering approaches and emphasizes on the integration of different application systems across product life cycle management (PLM) stages. It is revealed that checking product information validity is difficult for the current computer-aided systems because engineering intent is at best partially represented in product models. It is also not easy to maintain the consistency among related product models because information associations are not established. The purpose of this review is to identify and analyze research issues with respect to information integration and sharing for future concurrent and collaborative engineering. A new paradigm of research from the angle of feature unification and association for product modeling and manufacturing is subsequently proposed.

https://sites.ualberta.ca/~yongshen/index_files/%5bMa%20Y%20S%202008%20JIM%5d.pdf

Paradigm shift: unified and associative feature-based concurrent and collaborative engineering

Design and fabrication of conformal cooling channels in molds: Review and progress updates

The cooling system of an injection mould is very important to the productivity of the injection moulding process and the quality of the moulded part. Despite the various research efforts that have been directed towards the analysis, optimization, and fabrication of cooling systems, support for the layout design of the cooling system has not been well developed. In the layout design phase, a major concern is the feasibility of building the cooling system inside the mould insert without interfering with the other mould components. This paper reports a configuration space (C-space) method to address this important issue. While a high-dimensional C-space is generally required to deal with a complex system such as a cooling system, the special characteristics of cooling system design are exploited in the present study, and special techniques that allow C-space computation and storage in three-dimensional or lower dimension are developed. This new method is an improvement on the heuristic method developed previously by the authors, because the C-space representation enables an automatic layout design system to conduct a more systematic search among all of the feasible designs. A simple genetic algorithm is implemented and integrated with the C-space representation to automatically generate candidate layout designs. Design examples generated by the genetic algorithm are given to demonstrate the feasibility of the method.

Plastic injection mould cooling system design by the configuration space method

This research extends our previous investigation of the automation of the preliminary design stage to the layout design stage of the cooling system design process. While the functional aspects of the cooling system are considered during the preliminary design stage, the layout design stage addresses both the functionality and manufacturability of the design. A graph structure is devised to capture a given preliminary design and a graph traversal algorithm is developed to generate candidate cooling circuits from the graph structure. Heuristic search is employed to develop the cooling circuits into the layout designs by generation of tentative manufacturing plans. A framework for fuzzy evaluation of the layout designs is developed to rate the various design alternatives generated. An experimental system is implemented to verify the feasibility of the approach, and examples generated from the system are presented to illustrate the major steps of the automatic design process.

A. C. K. Mok

Papers

Automatic layout design of plastic injection mould cooling system