3D Printing - Display Parts Finishing Solutions - PPSF (PolyPhenylSulFone) Finishing
PPSF or Polyphenylsuplhone is a high-temperature, high-strength and chemically resistant FDM (Fused Depositions Modeling) material, which is ideal for creating heavy duty parts and functional prototypes. The chemical resistance and durability makes it difficult, costly and time consuming to apply finishing processes to the PPSF material. To smooth PPSF material surface there are only two options used: sanding and milling. Sanding is a laborous process since PPSF is resistant abrasion. Performing milling with a CNC machine is also time consuming. The process requires long programming of the machine and the constant overseeing of the process by the operator.
If PPSF is used to make tools or molds, there is a new and faster alternative for surface smoothing, thermoforming. A thin sheet of plastic is drawn onto the surface of the PPSF part. While it conforms to the part’s shape, the plastic sheet does not transfer the layer lines to the outer surface. To preserve the mechanical, thermal and chemical advantages of PPSF, the thermoforming process uses sheets of plastic made from PEEK (polyether ether ketone) resin. Versus hand sanding, PEEK thermoforming can reduce lead time by 75 percent and cost by 90 percent.
How it works
Smoothing a PPSF part with an outer skin of PEEK is a relatively simple process that requires few modifications to a standard thermoforming operation. The key differences are that PEEK is the thermoformed material and the FDM part serves as the thermoforming mold. Following are highlights of the process. For a detailed, comprehensive description of thermoforming with FDM, see Stratasys' “Thermoforming for Prototype and Short-Run Applications” guide.
Select the desired thickness of the PEEK sheet that will be thermoformed. The recommended thickness range is 0.003 to 0.005 inch (0.08 to 0.13 mm), but sheets as thick as 0.010 inch (0.25 mm) may be used. Note that thicker sheets of PEEK will require more vacuum pressure during thermoforming and may resist drawing into small features. To compensate for the thermoformed sheet’s thickness, adjust the CAD model of the PPSF part by offsetting all external surfaces. Optionally, the CAD model may be modified to include a 0.050- inch (1.27 mm) deep ring around the perimeter of the mold. This ring will aid in bonding the PEEK film to the part. To simplify and expedite the thermoforming process, modify the FDM build parameters to make the PPSF part more porous. This allows the vacuum in the thermoforming machine to be pulled through the part without having to manually drill vent holes around its periphery. Do this in Insight by adjusting the raster air gaps of the two outermost surfaces to 0.001 inch (0.03 mm). Also, change the model’s body raster air gaps to 0.010 inch (0.25 mm) to promote air flow through the part. Next, build the PPSF part an Fortus system. After the build is complete, remove the supports in preparation for thermoforming.
Mount the PPSF part on a base plate cut to a size that fits on the thermoforming machine’s platen. The base plate can be made from any rigid material that will withstand the heat of the thermoforming process. Load the PPSF part in the vacuum forming machine and insert a sheet of PEEK material. To ensure that there is a strong mechanical bond between the PPSF part and PEEK film, adhesive-backed materials are suggested. Testing has shown that Victrex P500S, an APTIV PEEK film backed with silicone adhesive, works well for this application. Heat the sheet to 284-320 °F (140-160 °C) and draw it onto the PPSF part as soon as it reaches its forming point. Typically, this cycle should be completed in less than 20 seconds. Extended cycle times will cause the PEEK film to crystallize, which causes it to become stiff and opaque. To avoid crystallization, observe the PEEK sheet. As heat is applied, it will relax and then become taut. Once the PEEK sheet draws tight, quickly apply the vacuum and hold it until the PEEK film cools. Following the vacuum forming operation, trim the PEEK sheet to the size of the PPSF part. The PPSF/PEEK part is now ready to be put into service.
The Proto3000 Advantage
Create highly precise FDM parts or functional prototypes with our lineup of Stratasys Production 3D Printers. The Proto3000 manufacturing facility is equipped for PPSF finishing processes. Call the Proto3000 Services Team NOW for your display part finishing projects.
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The Technology Used for Our Display Part Finishing Solutions
Fused Deposition Modeling (FDM) Technology
Using FDM technology allows affordability and durability by printing concept models with production-grade thermoplastics.
FDM 3D Printers are office friendly and they produce small models in hours and large models in days. The FDM printed models can be drilled, sanded and painted according to your preference to create a perfect finishing of your prototype.
PolyJet 3D Printing Technology
As a 3D printing process, this technology produces amazingly realistic models. The printing technology builds accurate models by incorporating multiple materials into one automated part to create prototypes that look and feel like finished products. With fine details, smooth surfaces, rigid housings, soft-touch buttons, lettering, rubberlike seals and even clear components, your models can look the part at a trade show, a presentation or even during a sales pitch.