Extrusion is a high-volume manufacturing process in which any of a multitude of polymers are melted, formed into a continuous profile and then cut to length. The process results in a wide variety of low cost, high volume products that show up in every aspect of our lives from drinking straws, medical tubing and piping to weather stripping, deck railings and window frames. But because they are so common, profit margins can be slim and manufacturers are looking at every angle to find ways to lower costs and increase their margins.
Central to extrusion is the die. It molds and shapes the polymer into the finished product and is the key to a profitable process. However, most companies continue to design their own extrusion dies, depending on the experience of their die designers and using trial-and-error prototyping. These methods have changed little in the past half century. While the out of pocket cost of dies can range anywhere from $1000 to $10,000 there can be steep hidden costs.
First, trial-and-error takes time that eats up engineering capacity and slows response to customer requests. In fact, the cost and availability of tooling could be the deciding factor in winning contracts.
Second, a poorly designed die can produce inconsistent product and excessive scrap that increases manufacturing costs. The more complex the profile shape, the higher the risk.
So what is an extrusion engineer to do? Try CFD!
ANSYS PolyFlow allows companies to compensate for changes in local flow velocities, which induce deformations in the extruded profile. The difference between high speed flows (red) and slower flows along the wall (blue) induce deformations in the final product.
CFD enables the engineer to virtually design and test dies by simulating the extrusion process and automatically performing die shape optimization. All this can happen before any metal is cut. Once a stable result is achieved in the simulation, the die prototype can be built to validate the results. Experienced users of ANSYS Polyflow have been able to reduce the number of die iterations by 50% or more.
They have been able to:
- Consider multiple design options making “what if” strategies easy
- Design dies faster
- Understand and eliminate flow related problems
- Enjoy reduced costs for engineering and extrusion line time, die fabrication, and scrap material. One company using simulation for die design experienced a 200 percent ROI the first year!
Learn more and watch a webinar showing how ANSYS Polyflow can help you speed the design and creation of extrusion dies.
What has your experience been with extrusion molding? Have you been able to try CFD? I’d love to hear from you!
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