Mechanical Engineering Design: The Role of DFM and DFA
What is Design for Manufacturing?
Essentially, DFM refers to the best practices being followed in the design of end products, parts and machine components which greatly reduces the cost of manufacture because it takes care of several factors including raw material costs, tolerances, quality methodologies being used (SPSS, Six Sigma etc.), and testing procedures. It gives a whole new fillip to product design because its main role is to help identify stress and strain factors in the product in advance, while providing a means to map and monitor defects avoidance. It further visualizes any possible ergonomic aspects which can impact the usability of the end product and future sustenance requirements. Basically, DFM is one of the best ways to achieve cost leadership, quality assurance and fulfilling sales objectives.
Some of the ways DFM can help reduce costs and achieve better design:
• Using common datum features and primary axes
• Tapping into existing marketing knowledge, DFSS techniques, process capabilities
• Optimized design to ensure fast production-readiness
• Better symmetry in design
What is Design for Assembly?
Design for Assembly (DFA) refers to the best practices being followed in the design of end products, parts and machine components which ensures reduction in overall costs during assembly. It follows the principle that individual components are more difficult to design, than final assemblages. A lot of costs can be saved if the design keeps in mind the final assembled product instead of singular parts. The Sony Walkman was one of the first products to follow DFA principles which explains its rapid popularity and uptake in the early 1990s. DFA allows more flexibility in terms of incorporating product safety features and workmanship. This plays out in the following ways:
• Rapid fastening of features
• Minimized relocation of parts and components
• Saving of money in material costs
• No repetitive work
• Testing the assembled product in initial conditions such as temperature, humidity, vibrations etc.
• Part controls
In order to meet functional requirements of product manufacturing, assembly design has to be more seamless. As a result, DFM and DFA often come together in what is today known as Design for Manufacturing and Assembly (DFMA).
Design and process improvements sit at the heart of a successful product development initiative. The basic way to do it is through minimization of parts involved in design. DFMA analysis is based on knowledge behavior where functional design has to be taken into account. DFMA analysis helps align the marketing position of the company with cost, purchase and material requirements. Some of the factors that are taken into account include:
• Understanding the movement of all parts and components with respect to their neighboring parts and components
• Understanding the material requirements of various parts and knowing about replacement procedures
• Reducing complexity of design to an easy level so that best value can be derived from the entire operation
• Achieving final value
Mechanical engineering services are focusing on details of value engineering where “small is increasingly better” and migration from old methods to new is in vogue through legacy conversion. Increasingly, Design for Manufacturing and Design for Assembly are seen as the best ways to get results.
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