R D Allen

CAD/CAM solutions for STEP-compliant CNC manufacture

The ability to generate an NC tool path is now commonplace in CAD/CAM systems, but the technology used for programming and control of NC machines is still based on 1950s standards. Today, under the IMS project called STEP-NC in Europe and Asia, and Super Model in USA, industrialists and academics are collaborating to deliver a new data model as an ISO 14649 standard for CNC machines. This standard will enable software vendors to revolutionize the programming of these machines. This paper provides a futuristic view of how this standard could be used in manufacturing and highlights a number of possible generic frameworks for how CAD/CAM systems may evolve using the ISO 14649 standard. Finally, the paper proposes a prototype STEP-compliant CAD/CAM system based on one of these frameworks using the new ISO 14649 standard for milling components.

Surface roughness prediction model for CNC machining of polypropylene

Cutting strategy research has traditionally been focused on hard materials that are intrinsically difficult to machine. An increase in the desire for personalized products has led to the requirement of the direct machining of polymers for personalized products. Little research is evident in the literature on the analysis of optimal machining parameters for machining materials such as polypropylene. One of the vital factors that affects the quality of polypropylene products and the respective machining strategy is surface roughness. This research is aimed at extracting information on the machining of polypropylene materials. A surface roughness predictive model based on neural networks has been developed. The design of experiments approach is used to obtain an adequate predictive model for the process planning which is further utilized as an input to the predictive model. The model mainly hinges on three independent variables namely spindle speed, feed rate, and depth of cut. Extensive experimental work on different network topologies and training algorithms has been performed to predict the behaviour of the surface roughness for machined polypropylene products. The results illustrate the benefits of being able to determine surface roughness values. This allows for the determination of optimal cutting strategies and tooling for the required surface roughness. The performance predictive model has been found to be satisfactory over the dataset for polypropylene machining. Hypothesis testing has also been carried out to identify the confidence of the predictive model.

Application of mobile agents in interoperable STEP-NC compliant manufacturing

As the ratio of transport costs to total product cost increases, manufacturers try to fulfil the demands of each geographical region with products manufactured within the same region. Since the manufacturing resources available at each venue can be varied, it is necessary to adapt the manufacturing process plan for each production facility. Traditionally, this process is carried out manually by engineers utilizing computer-aided design (CAD) files. With the advances in artificial intelligence technology and emergence of integration standards such as STEP, it is now possible to automate the CAD/computer-aided manufacturing (CAM)/computer numerical control (CNC) interface. Distributed artificial intelligence techniques and mobile agents in particular can be used to transfer information throughout the manufacturing network and construct the distributed knowledge-base required for the intelligent interoperable integration of product data models and manufacturing resources. This paper explores the application of mobile agents as enablers of interoperability in a global manufacturing enterprise. A novel manufacturing chain based on the STEP-NC standard is proposed and the application of agents for transfer of manufacturing information is studied. The research is demonstrated through the use of a prototype manufacturing decision support system developed using agents.

Feature-Based Process Planning For Interoperable STEP-NC Manufacture

Abstract With the progress on STEP-NC standardization and implementation, STEP-NC-oriented computer systems in the process chain require evolution to support the STEP-compliant planning and manufacture. This paper explores process planning (CAPP/CAM) based on STEP-NC and presents a CAPP prototype system (PPS) in the light of future interoperable planning and manufacture. The PPS has been developed using STEP-NC features throughout the planning process and applies a two-stage strategy for STEP-NC part program generation, namely general workplan generation and specific workplan generation. The work is verified through use of case study components.