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Tracking data | DFM


Closing the loop


Completion of a structured and detailed upfront Design for Manufacturing (DFM) programme not only enables the optimization of the design of an injection moulded component prior to tool construction and production, it also allows the design team to control production costs and to carry out very specifi c and precise computer- based predictions on cycle time, number of cavities, tool setup and required moulding equipment. This detailed analysis allows the design team to determine whether the anticipated future production volume can be achieved or if more capital investment will be needed. The predictions made during the DFM process will


typically be taken as the calculation baseline for a project. Once fi xed, they must meet the numbers achieved later on in production. For planning purposes, one of the most important fi gures is the cycle time. It is clear that, when combined with data on the number of mould tools and cavities in use, cycle time determines production volumes. But cycle time can also provide a basic but effective indicator of part quality, which can suffer if the injection moulding machine is not run within the DFM determined specifi cation. The intention of this article is not to get involved in


the details of process optimization, which is a topic on its own. But, during the DFM process, a cycle time will


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DFM considerations do not end at


mould qualifi cation. André Eichhorn discusses the importance of ensuring processing specifi cations are maintained in production


have been determined and the mould tool and the injection moulding process will have subsequently been qualifi ed to this specifi c target. It is important that once production is underway, that this cycle time is held to. If the cycle time is allowed to divert from this qualifi ed value, it can put quality, dimensions as well as the production volume of a component under risk. Many of the customers that AST provides in-depth


DFM, tool specifi cation and approvals to outsource their moulds to contract moulding companies for production. For a number of reasons, fully validated mould tools may subsequently undergo changes to their qualifi ed injection moulding settings. For example, it may be decided to run a mould tool on a longer cycle time to extend the tool life and to reduce predicted mould maintenance efforts.


January/February 2014 | INJECTION WORLD 61


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