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Twin-sheet thermoforming is a process of vacuum or pressure forming two
sheets of plastic essentially simultaneously, with a separate mold on
the top and bottom platens. Once the plastic has been molded, it remains
in the molds, and while still at its forming temperature the two molds
are brought together under high pressures, and the two sheets are welded
wherever the molds dictate a weld. The process creates 3 dimensional
parts with formed features on both sides. The parts are typically very
strong, stiff, and quite light-weight.
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Step 1: Two preheated thermoplastic sheets are
simultaneously heated between the two molds till they are are
entirely plasticized. |
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Step 2: On reaching the the specific temperature the two
molds move together. The
two Sheets are deep-drawn and tightly molded to each other in one
step. No
adhesives are used. There are neither resulting pressure nor strain. |
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Step 3: To achieve a high level of detail or precision,
the forming can be supported by high pressure or (and) vacuum |
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Step 4: ... and the hollow body, without solvent, molding
additives and adhesives,
is finished. Furthermore, there are no inner strains. |
Materials
- H.M.W. HD Polyethylene
- ABS
- PC/ABS
- Polycarbonate
Typical applications are:
pallets, industrial dunnage, portable toilets, medical housings,
surfboards, fuel tanks, air/ventilation ducts, electrical enclosures,
recreational boats, cases, toys, marine products, doors, tables, spine
boards and numerous transportation-related products.
Main Advantages
- Increased Structural Integrity and Rigidity
- Enclosed Cross-Section Capability
- Low Tooling Cost
- Internal Reinforcement Options: Structural Member, Rigid Foam,
Etc.
- The process has some distinct advantages over blow-molding and
rotomolding.
The process has some distinct advantages over blow-molding and
rotomolding.
Compared to blow-molding, the twin-sheet process:
- Tooling and machines are more cost-competitive for small to modest
run sizes.
- Each sheet may be a different thickness, material or color.
- More flexibility with parting line structure is possible.
Compared to Rotomolding, the twin-sheet process:
- Many more resin types are available in twin-sheeting.
- More structural beams can be created in twin-sheeting
- Much higher production rates
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Molding
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