Enhance Your Thermoforming Molds with Additive Manufacturing

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Whether they are on your car, at the grocery store or in your company’s break room, thermoformed products are a part of everyday life.

Thermoforming is a collection of manufacturing methods commonly used for the production of high volumes of lightweight plastic parts, such as blister packaging and disposable cups, and larger products like automotive wheel covers and refrigerator door panels. The process works by heating a plastic sheet to a pliable temperature and then forming it around a mold. Two of the more common methods are vacuum forming, which draws the sheet against the mold with a vacuum, and pressure forming, which instead uses compressed air to force the sheet onto the mold.

vacuum-form-tool

Typically, these molds are machined out of wood or aluminum. However, companies have started using Fused Deposition Modeling (FDM) as an alternative process to produce molds faster and more efficiently.

Turning to FDM and additive manufacturing can advance your thermoforming applications in the following ways:

Reduce lead times: Thermoforming tools require vent holes to draw the plastic onto the mold. For machined molds, vent holes need to be drilled in manually which adds to production time and risks them being drilled unevenly. With FDM, parts are naturally porous, allowing for a finely distributed vacuum draw without the need for vent holes. One Stratasys Direct Manufacturing customer was able to reduce lead times for a thermoforming tool by 60 percent using FDM molds.

Lower costs: Machining a pattern out of wood or aluminum can require multiple set-ups and additional labor, which increases production costs. 3D printed FDM parts are built following an automated process that begins as soon as the design file has been prepared. And if design modifications are needed post-build, an updated mold can be printed almost immediately following adjustments to the original file.

Create custom mold densities: With FDM you can set the internal structure of the mold to a specific density. Instead of building it solid, designing a lattice or honeycomb structure inside solid walls will promote air flow through the mold, in addition to reducing build time and cost. Different areas of the part can be designed with varying densities, for example, you can increase the density around deep draws to enhance strength and avoid damage to the mold.

Increase strength: FDM parts are made with engineering-grade thermoplastics like ABS, polycarbonate (PC) and high-strength materials such as PPSF and ULTEM. This wide range of durable materials ensures that your molds will resist the heat and pressures of thermoforming, extending their service life. Although an FDM tool life will not equal that of aluminum, the materials available with FDM are strong enough for functional prototyping and short-run manufacturing.

Eliminate secondary operations: For thinner gauge plastic sheets, a mold surface needs to be especially smooth. In order to meet these requirements, FDM parts can be finished in a wide variety of ways including sanding, bead blasting and vapor smoothing. Aesthetics can also be impacted by the build orientation, or the direction by which a part is built in an FDM machine. Consult with a Stratasys Direct Manufacturing engineer to choose an orientation that will maximize functionality while achieving the aesthetics you need.

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