Twin-Sheet Pressure Forming is a process where 2 sheets are kept separate while heating, then brought together in a double female mold arrangement. A blow pipe is inserted between the 2 sheets and air pressure inflates them against the respective molds. Twin-sheet forming can produce a relatively flat, hollow part with injection molding cosmetics and strength and stiffness not available with straight pressure forming.
Some applications where Twin-Sheet Pressure Forming can be used include:
- Security Gate Panels
- Large Electronic Panels
- Air Plenums
- Instrument Cases
- Tractor Roofs
- Material Handling Trays
- Side Panels
Dimensions – Tolerances
Please see the sheet titled “Standard Manufacturers’ Tolerances” for guidelines.
Draft angles for female (negative) aluminum molds should be 2° – 4° to prevent lockup of part in mold. Deep parts or complex configurations, texturing on the tool side, may require more draft angle.
Radii and Fillets
Radii and Fillets should be as large as possible. Sharp corners may be attained on shallow draw areas. Keep in mind that larger fillets and radii make stronger, stiffer parts and create thicker corners.
As in vacuum forming, material starting thickness will thin when part is formed. However, the amount of thinning will depend upon shape, size, depth of the draw, radii and fillets. For any special design considerations in Twin-Sheet Pressure Forming, pelase contact the Mayfield Plastics’ sales engineering team. For information on emi shielding check here.