Pressure Forming | Pressure Thermoforming | Blow Forming

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Pressure Forming:

Pressure Forming is the method used to produce injection mold quality, high definition plastic component parts, housings and containers without the huge expense of tooling. It involves positive pressure to force the heated plastic into the mold cavity. This is called pressure thermoforming or blow forming

Pressure Forming Working Operation:

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The highly versatile pressure forming process utilizes air pressure, from 20 to 150 psi, to force the heated sheet into a temperature controlled mold cavity. Vent holes are provided in the mold to exhaust the trapped air. The final part features sharp definition of intricate contours and tight radii. Textures and accurate details are built right into the tooling. Low-cost, highly aesthetic plastic parts of varying sizes are possible due to the application of air pressure, as well as more sophisticated process controls that better monitor tool and sheet temperatures while controlling material shrinkage during forming.

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Types Of Molding operation:

  • Positive Mold
  • Negative Mold

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Negative molds  have concave cavities. A positive mold has a convex shape.

Pressure Forming over Thermo Forming:

The basic advantage of Pressure Forming over Thermo forming is the cost advantage for small production items. The mould cost for thermo forming is considerably higher in comparison to pressure forming thus for a lower quantity precision job the best suitable method used is pressure forming.

Application:

Pressure forming is used to create in a wide array of plastic products used for packaging of food trays, blisters, covers, internal parts, housings equipment, bezels, bases, and spare parts for use in business machines, electronics, computers and peripherals, bio-medical applications, and instruments.

Features:

Pressure forming achieves features beyond the capabilities of vacuum forming including louvers, ribs, recessed areas, crisp details and logos.

Pressure forming is ideal for small to medium sized production runs that do not justify the high cost of injection molding dies. Additionally, because the aluminum tooling used in pressure forming has an unlimited lifecycle, due to the non-abrasive process versus injection, it saves a great deal of money over many years of continued use. Pressure form tooling usually costs less than 10% the cost of an injection tool. There is also a significant time savings (sometimes 25%) in tooling lead time. Sheet gauges .020" – .500" are capable of being pressure formed.

Twin Sheet Forming | Twin Sheet Thermoforming | Twin Sheet Vacuum Forming

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Twin sheet thermoforming has advantages over other methods of thermoforming and other plastics manufacturing processes depending on the part and its use.

  • Has a lower tooling cost – about 20-30% less than blow molding
  • Yields parts with high structural integrity and rigidity compared to single walled thermoforming
  • Allows for an enclosed cavity
  • Can include various internal reinforcements, including structural elements and rigid foam components
  • Can have molded-in attachments and other features

Typical Application:

To Produce Hollow Molding Parts, Structural Products.

Working Of Twin Sheet Thermoforming Process:

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Twin sheet forming is a process of vacuum and compression forming two sheets of plastic simultaneously with a separate mold on the top platen and a separate mold on the bottom platen. Once the plastic sheets have been vacuum formed, they remain in their respective molds. While both sheets still remain at their forming temperature, the two molds are brought together under high platen pressures and the two sheets are bonded together wherever the mold-designed knit areas dictate. This will result in one single product with hollow areas and no secondary bonding required.The twin sheet process creates 3-dimensional parts with formed features on both sides.

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The production of twin sheet pallets up to 4 pallets per cycle are being made giving an individual cycle per part in seconds, not minutes. Production capacity therefore can be as large as required by sizing the equipment as required.

Methods:

  • Vacuum Forming
  • Pressure Forming
  • Mechanical Forming

Properties:

  • The parts are typically very strong, rigid and lightweight.
  • Increased Structural Integrity
  • Enclosed Cross-Section Capability
  • Low Tooling Cost
  • Internal Reinforcement Options: Structural Member, Rigid Foam, Etc.

Materials:

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HIPS, Acrylonitrile Butadiene Styrene (ABS), TPO, High Density Polyethylene (HDPE), Polypropylene (PP), TPU, & PETG

Important Points:

After forming of the bottom sheet and the entry of the top sheet into the forming area, there is an opportunity to insert other items such as wood, metal, foam etc. These can be inserted to add strength, give the ability to attach the final product to other items after forming, such as door hinges or even give the final product the ability to float as in the manufacture of floating docks. Also engineering plastics can be thermoformed by this method into detailed technical twin sheet parts.

Application:

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  • Pallets,
  • Industrial drainage,
  • 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.