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Flow analysis | DFM Make the most of simulation


Flow simulation tools such as MoldFlow, CADfl ow, Moldex3D and the like are simple to use and provide increasingly accurate predictions. Unfortunately, it is a fact that fl ow studies are not performed on every new component design during the DFM phase. Too often, an analysis will only be performed on a component once it is in production and causing issues. Flow analysis can then only confi rm problem areas. Performing a fl ow analysis during the DFM process means it is possible to change problem areas, saving a signifi cant amount of money that would otherwise be spent on people traveling around and mould tools being modifi ed. Figure 1 shows how precise fl ow analysis can be by comparing the fi lling pattern from a fl ow study with a physical short shot study from the fi nal mould tool. And a fl ow study should not only be used during DFM


for troubleshooting - the fi nal component design should be analysed again purely to ensure all fi nal data is on hand to setup the basic process parameters on the injection moulding machine. For example, a very important aspect for the toolmaker is to ensure venting requirements are incorporated into the tool design. This will save a great deal of hassle by avoiding short shots and burn marks on complex components. Incorporating a fl ow study into the DFM process


means information can be provided to the toolmaker as a part of the Tool Specifi cation Sheet, which also contains other tool and component design-related data for the tool designer. One AST Technology client found


www.injectionworld.com


Computer-based fi ll simulation is an invaluable design tool but is too often left out of the DFM process, writes André Eichhorn


that specifying a fl ow study for every component requiring new tooling enabled it to reduce its trouble- shooting costs for problem tools in production by 70% (including costs for travel, resources, tool and compo- nent changes). A fl ow study can reveal a huge amount of data. Here


we examine the main areas that can be analysed and the benefi ts that can be realised:


Gating and material selection Once a component design is meshed and prepared for the analysis it is possible to test several gating solutions and evaluate moulding materials. This can be done without additional effort as long as the component geometry does not change (otherwise a new mesh needs to be created). Most fl ow analysis applications also provide the opportunity to design the anticipated coldrunner layout; it is always good practice to include the coldrunner geometry in the analysis as some performance loss will result from it.


October 2013 | INJECTION WORLD 79





IMAGE: AUTODESK


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