Thanos Kanatsoulis: DFMA (Design for Manufacturing – Design for Assembly) for mass production of small wind turbine
DFMA is used as the basis for concurrent engineering studies in order to provide guidance to the design team in simplifying the product structure, to reduce manufacturing and assembly costs, and to quantify improvements. The practice of applying DFMA is to identify, quantify and eliminate waste or inefficiency in a product design. DFMA is, therefore, a component of Lean Manufacturing and is also used as a benchmarking tool to study competitors’ products, and as a ‘should-cost tool’ to assist in supplier negotiations. There are various DFMA methods used globally. Three of the better-known quantitative evaluation techniques are those of Boothroyd-Dewhurst (USA), Lucas (UK) and Hitachi (Japan). All three are being used for industrial purposes. The Hitachi Assembly Evaluation Method (AEM) was first developed in the late 1970s, with Design for Assembly (DFA) being introduced later (around 1980) to reflect the work of Professor Geoffrey Boothroyd at the University of Massachusetts. Professor Boothroyd and Dr Peter Dewhurst coined the term “Design for Manufacture and Assembly” (DFMA) to reflect their continued work into manufacturability analysis (machining, die-casting, powder metal, etc.) and assembly techniques. On this essay we are using the Lucas method.
The first part of this essay is the application of DFA method on Piggott’s turbine. This method combines theory, experiment and experience. It points on the analysis of the design and the subsequent difficulties on the overall assembly of the parts. The original philosophy of DFA, to reduce component count and ensure assemblability and handlability of the remaining components, has been built upon and expanded by many sources. The final aim of this process is to optimize the assembly so that it becomes an easier and cheaper process. At the same time, the factors of high productivity rates and low cost of manufacturing are highly important. In order to achieve the above, each part is analyzed according to some principles that derived from the revolution of manufacturing of industrial parts and are based on old design malfunctions and failures. After the analysis of each part, comes a numerical value which occurs at the end of the procedure. If this value exceeds a particular limit, then the component has to be redesigned.
The second part of this essay is the application of the DFM method for Piggott’s turbine. The aim of this method is to design a product which can be manufactured easily and at low cost. This is achieved by taking into account the limitations related to manufacturing at the early stage of the design. Using this technique, the designer engineer can make a selection among the different materials, different technologies and estimate the manufacturing cost quantitatively and rapidly among the different schemes. According to the feedback information of the analysis, you can determine the most satisfying design and technology plan. Finally, in this method, each part is analyzed and has a numerical value that, combined with all other parts, is a cost indication. The optimization is achieved by obtaining the minimum value for each part.