Thermoforming heavy gauge

Heavy-Gauge Machines. There are several common designs for heavy-gauge thermoforming machines. The simplest and most widely used is the shuttle machine (Fig. 5) (14), where the sheet, cut to size and palletized, is loaded, one... 

Fig. 5. Schematic of heavy-gauge shuttle thermoforming machine (Drypol/Zimco, no-longer in business) (14). Used with permission of Hanser Publications.

Sag bands or metal rods that mn length of the thin-gauge oven have been used for polymers that sag excessively when heated. Some heavy-gauge shuttle thermoforming machines are equipped with ovens that completely seal the sheet between the heaters. These ovens are equipped with vacuum and compressed air, so that the sheet is lifted when it begins to sag. 

Fig. 16. U.S. plastic materials consumption for thin-gauge (2.1 million metric tons) and heavy-gauge (682,000 t) thermoforming (32). PE = Polyethylene ABS = acrylonitrile-butadiene-styrene PS = polystyrene PP = polyproplyene PMMA = poly(methyl methylacrylate) PVC = poly(vinyl Chloride) PET = poly(ethylene terephthalate). Redrawn and used with permission of SPE Thermoforming Division.

Fig. 22. Bottom wall thickness variation during normal production—heavy-gauge ther-moformed part (41). Redrawn and used with permission of SPE Thermoforming Division.

Figure 16.17 Schematic of three-station thick-gauge rotary thermoforming press detailing major components (Note Four-station heavy-gauge rotary thermoforming presses have a preheating station prior to the primary oven).

The cut sheet may be manually inserted into the clamp frame of the thick-gauge thermoformer, but vacuum pick-up and placement devices are more common for long production runs. Pneumatic or mechanical tables are used to Uft very heavy or large sheets. Pneumatic clamp frame closures are usually... 

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