Chapter 5 basic design for manufacturing
- 1. ME3101 / ME3102 Mechanical Systems Design Chapter 5 Basic Design for Manufacturing
- 2. DFM - Design for Manufacturing? While product specifications and customer’s wants are important, there are other design issues to consider. DFM decisions are applied throughout the design process and it affects all aspects from the design phase to the production phase Consider: •Costs control •Methods of production •Time required to production •Production process impact on performance •Availability of raw materials
- 3. DFM - Design for Manufacturing? Ask the following questions: •Can the same demands be met with a cheaper material? •Is it possible to use lesser material? •What kind of materials are available? And in what specifications? •How many units do I have to make?
- 4. Estimating Manufacturing Costs Estimate manufacturing Costs of Proposed Design Reduce costs of Reduce costs of Reduce costs of components assembly Supporting Production Consider DFM impact on other factors Recompute Manufacturing Costs N Y Good Enough? Accepted Design Extracted from: Karl T. Ulrich, Steven D.Eppinger (2008) Product Design and Development McGraw Hill International
- 5. Breakdown of component costs Components of a product may be: •Standard parts. Available for purchase from vendors. •Custom parts that require modifications by vendor. (Different sizes/dimensions/finish etc.)
- 6. Comparing costs of standard components Do: •Compare costs of different suitable materials to explore alternatives •Obtain quotations from several vendors to make comparisons •Some vendors offers a discount if multiple purchases are made or when purchase quantity is high. Students can find a list of useful vendor contacts on the website. The link is under the resources tab Sample Vendors
- 7. Costs of custom components On top of the base Material Costs, custom made components costs more due to: 1. Additional processing steps required (Eg. Machining) 2. Additional overhead costs for processing
- 8. Reducing Component Costs Reductions of component costs requires the following: •Understand process constraints and related costs •Eliminate processing steps through smart design •Selection of production methods w.r.t. scale of production •Standardization of components
- 9. Process Constraints •Understanding process constraints are important as designers might create features that are difficult to achieve in manufacturing •Examples: •Delicate internal features are difficult to manufacture using standard processes. EDM might achieve a small internal corner radius, but the process is costly •Tight tolerances are difficult to attain
- 10. Eliminating Process Steps Complicated Design Simpler Design
- 11. Eliminating Process Steps While most real life examples will not be as simple as the comparison made between the bikes, some general guidelines can be followed to reduce processing steps: •Reducing number of components. Make it as one whole piece rather than many small pieces fixed together. •Eliminate redundant steps. For example, painting internal components that are not visible. •Wherever possible, avoid using complex shapes.
- 12. Economies of scale Hypothetical costs vs number of units When considering the number of units to be made, take into consideration: 1. Initial start up costs Costs Machining Injection Molding 2. Incremental costs per unit There will be a point of Number of units production volume whereby another production method will An example to show that at certain production be more economically viable. volumes, alternative production methods becomes increasing viable
- 13. Standardization of Parts During the design process, it will be good for the designer to try to use the same components as much as possible. For example: 1. Using the same drill sizes and screws 2. Using the same length of materials This reduces the types of tools required and minimizes processing time.
- 14. In conclusion… Take into consideration the ease of manufacturing during the design process! While the design can be spectacular, it means nothing if it cannot be made!