ProComp Fabrication and Forming

Reinforced polypropylene available exclusively from Curbell Plastics

ProComp Technical Considerations

Sheet Heating

  • 380°–410°F: top surface
  • Measured with portable IR thermometer

Reinforcement

  • ProComp can also be used as a reinforcement when fabricating an orthosis. For example, you can laminate a strip of ProComp into the AFO to strengthen the ankle.

Cosmetics

  • ProComp is compatible with standard polypropylene heat transfer image papers.

Vacuum Forming

  • Minimum of 20″ Hg of vacuum with 420 cu.ft./min of flow.
  • Surge tank required. 

Corrugation

  • Corrugation as a means to selectively improve the rigidity of an orthosis is compatible with ProComp.

Lab Processing

  • ProComp is compatible with the standard vacuum thermoforming process utilized by orthotic and prosthetic laboratories. Measure and cut the fabrication coupon from the original laminate in the standard fashion. Set up of the positive model with a bleeder layer on the top of the plaster surface. Nylon hosiery will work as the interface for vacuum forming.

Heating

  • If you are using an infrared oven to heat your materials, you must minimize the temperature differential between the top and bottom surfaces.

Melt Temperature Sag Strength

  • The carbon fibers in ProComp improve sag strength to ease the transfer of the sheet from the oven tray to the positive model.

Molding (Drape Forming)

  • ProComp’s carbon fibers slightly resist the draping of the laminate onto the positive model. Gloved finger pressure should be used to flatten the dart in the material at the fold of the ankle and foot in the fabrication of an AFO.

Molding (Blister/Bubble Forming)

  • For best results, ProComp needs to be evenly heated to forming temperature throughout the complete thickness. Uneven heating can produce minor ripples on the exterior. It is also important to get and maintain a good vacuum seal when pulling ProComp. Any loss of vacuum as material is cooling can cause imperfections on the interior of work piece.

Trim Out

  • ProComp can be cast saw trimmed from the positive model once the surface temperature can be touched with bare hands (below 120°F).

Finishing

  • Standard router finishing cones that are compatible with polypropylene can be utilized.

Safety

  • Dust mask and eye protection should be used.

Wall Thickness:

  • It is necessary to minimize excessive stretching of the material while molding to prevent the development of surface orange peel, especially in the area of the heel and instep in an ankle foot orthosis. The surface orange peel effect will occur in this area. It is common to see some surface “blocking,” as it is called by the polymer engineers, in the presence of too much stretch. It is critical that the darts or folds that occur during molding of the ProComp around the ankle be managed by gloved finger manipulation rather than just stretching or pulling the material to move the darts beyond the trimlines of the finished product. The end result will be a reduction in the blocked or orange peel surface effect and increased wall thickness, which will offer increased sagittal plane stiffness in the orthosis.

Positive Model Archive

  • It is recommended that you archive positive models in cases with expected high gait loads. Polypropylene has a 40-year history of use with respective success and failure potentials. The predicated design of ProComp allows the practitioner the ability to extend their current polypropylene design portfolio into an expanded realm with the use of a material that may be considered a “super polypropylene.” But take note: The descriptor “super” should not be taken as meaning it is unbreakable. All materials have their design limitations. 

Disclaimer:
Material processing temperature and vacuum molding pressure are critical elements of successful ProComp fabrication. It is the responsibility of the fabricating lab to control process elements.