P08428: Design for Manufacture Introduction Christine Lagree Industrial Engineer Product Design and Development, 4th Ed. Karl T. Ulrich and Steven D. Eppinger 3/13/2008
Overview of the DFM Process Estimate the manufacturing costs. Reduce the costs of components. Reduce the costs of assembly. Reduce the costs of supporting production. Consider the impact of DFM decisions on other factors. 3/13/2008
1) Estimate the manufacturing costs. Component costs Standard (purchased from suppliers) Custom (designed in house, raw materials, processing, tooling) Assembly costs Labor Equipment and tooling Overhead costs Support costs (material handling, QA, purchasing, shipping, receiving, facilities, equipment maintenance) Indirect allocations (cannot be linked to one product but necessary to stay in business, not relevant to DFM) 3/13/2008
1) Estimate the manufacturing costs. Fixed costs Incurred at a predetermined amount, regardless of how many units are manufactured (machines, tools, may change over time) Variable costs Incurred in direct proportion to the number of units produced (raw materials) 3/13/2008
2) Reduce the costs of components. Redesign components to eliminate processing steps Economies of scale Fixed costs are divided among more parts Variable costs are lowered, justification to buy larger and more efficient equipment Standardize components and processes 3/13/2008
3) Reduce the costs of assembly. DFA index = (theoretical min # of parts) x (3 seconds) Estimated total assembly time 3 seconds reflects the theoretical minimum time required to handle and insert a part that is perfectly suited for assembly (quick as placing ball in circular hole) Maximize ease of assembly Part is inserted from top of assembly Part is self aligning Part does not need to be oriented Part requires only one hand for assembly Part requires no tools Part is assembled in a single, linear motion Part is secured immediately upon insertion Consider customer assembly 3/13/2008
4) Reduce the costs of supporting production. Inventory management # production workers Supervision Engineering support Quality assurance Minimize systemic complexity # of new parts, new vendors, custom parts, new major tools, new production processes Error proofing Exaggerate differences Eliminate subtle differences Color code (not to add time to production) 3/13/2008
5) Consider the impact of DFM decisions on other factors. Development time Annual cost savings vs. delay time Development cost Product quality Ex: reduce size (amount of mat’l), reduce product strength External factors Component reuse Lifecycle costs (toxic materials, service costs, warranty costs) 3/13/2008