Thermoforming Sheet Plastics
Thermoforming is a common practice in P&O to fabricate test sockets, flexible sockets, orthoses, and other products. It may be used with various types and thicknesses of thermoplastic sheets. Common plastics used in P&O are LDPE (low density polyethylene), HDPE (high density polyethylene), PP (polypropylene), Copolymer, Surlyn, Proflex with Silicone, Subortholene, PETG, Kydex, Pelite and Plastizote.
Thermoforming plastic is a process used to alter the shape of sheet plastic over a positive model. The plastic sheet is heated in the oven at a pre-specified temperature. Once the plastic has reached its melting point, the plastic is then draped or pulled over the positive mold using vacuum suction. Care must be taken to avoid wrinkles and imperfections. There are two general types of thermoforming, aka vacuum forming, used in P&O: 1) blister forming or bubble forming (Figure 1), and 2) drape forming (Figure 2).
Additional resources
Draping Polypropylene AFO with compcore
Fabrication Of Microcell Puff Innerboots For Use In Pediatric AFO’s
Introduction to Clinical Thermoforming 1 by Gary Bedard