The concept Design for Manufacturing (DfM) is ill-defined, which often results in DfM being brought into play far too late in the manufacturing process. In practice, this turns what should be a proactive design and manufacturing process into a reactive one.
An example of this is when the chassis architecture design team of a leading automotive manufacturer approached Sarginsons to support the first phase of a new concept for the use of common aluminium chassis architecture across future new vehicle launches. Because none of the Tier one assembly organisations had been involved prior to the final designs being frozen, there were many costly engineering changes made throughout the programme. Every one of these changes could have been avoided had robust DfM processes been implemented at the design stage.
Another example is an analysis of sheet metal manufacturing, as seen by Metal Working World magazine, where it was estimated that metal sheet manufacturers spend between 30% and 50% of their time fixing errors and almost a quarter of those errors are related to manufacturability.
Getting the best out of DfM, therefore, means proactively designing products to optimise every stage of the manufacturing process. This ensures cost-effective production of the highest quality products and takes into account shipping, transportation, continuity of supply, customer service and regulatory and environmental compliance. While actual costs will vary on a part-by-part basis, it is a fact that the cost to repair defects in a part at the design stage will be significantly less than at assembly or distribution. In design flow terms, DfM should precede and define every prototype.
If the above factors are the key to realising value in the DfM process, it is clear that by far the most important factor is early adoption of DfM practices. In casting, where the aim is to minimise material volume in order to reduce weight and cost, DfM can mean designing pockets to reduce cross-section thickness, calculating where best to locate these pockets to optimise accuracy and reduce non-constant shrinkage, adding ribs on thin walls to increase strength, allowing tolerance where no draft is provided, designing an inside corner with a fillet and an outside corner with a radius where possible, avoiding holed and undercuts that are parallel to the parting line and combining a component’s features in one casting to save costs.
Despite the fact that avoidable, secondary processes can represent as much as 80% of the component cost, many companies still do not embrace DfM early enough. Sarginsons set up the Sarginsons' Technology Centre (STC) to rectify this problem. The STC de-risks every aspect of the manufacturing process by advising Product Directors and Engineers during the scoping and decision-making process and by acknowledging that the greatest value in DfM is always at the beginning!