WHAT IS VACUUM FORMING?
Vacuum forming is a type of thermoforming that involves taking a plastic sheet and draping it over a mold to form a part of a shape. The sheet is heated to form over the mold, and then completely vacuum-sucked to the mold so there is no air between them. Then, the sheet is removed from the mold and cooled off. Finishing services can be performed, including trimming if the sheet is too long for the actual part.
Vacuum forming utilizes either male or female molds; the former requires the sheet to be placed over the mold, and the latter has the sheet placed inside the mold.
HOW DOES VACUUM FORMING WORK?
There are several steps involved in the vacuum forming process, which begins with the clamping of the thermoplastic sheet into a frame. Heat is then applied until the sheet starts to sag.
Once the sheet has been heated enough to be formed, vacuum pressure is applied to pull the sheet across the mold and form the final shape. The next step is the cooling process, followed by the removal of the plastic part from the frame and the trimming of excess material.
WHAT KINDS OF PLASTICS DO YOU USE FOR VACUUM FORMING?
Many types of thermoplastic can be used in the vacuum forming process. Some of the most common materials include:
- HIPS (High-impact polystyrene)
- ABS (Acrylonitrile butadiene styrene)
- PET (Polyethylene terephthalate)
- PVC (Polyvinyl chloride)
- HDPE (High-density polyethylene)
- LDPE( Low-Density Polyethylene)
CAN POLYPROPYLENE BE VACUUM FORMED?
Yes. Below are some of the pros of using this type of polymer in the process:
- Polypropylene is less expensive than some other plastics.
- It is good at high temperatures, of 100°C and up.
- It is good in harsh environments.
Tips to keep in mind when vacuum forming with polypropylene:
- Putting cavities or moats in the mold can prevent the polypropylene sheet from sliding.
- Pressing the sheet between two surfaces also helps keep it in place.
- Female molds are better when using polypropylene sheets.
- Cooling times are about 50% longer than for other plastics.
BENEFITS OF VACUUM FORMING
Vacuum forming isn’t expensive, due to the low pressure required that allows molds to be made from less expensive plastics. The process is quick and efficient, so anything from prototypes to large production runs can be created easily.
Less tooling is involved than in traditional thermoforming, which can be very complicated. It is also a good alternative to other thermoforming processes, 3D printing, and injection molding.
APPLICATIONS OF VACUUM FORMING SERVICES
An expanding application is growing trays for greenhouse and indoor growing applications including flood benches, sub-irrigation, and re-circulation systems.
Some of the common applications include:
- Medical devices and components
- Machinery guards
VACUUM FORMING BY WS HAMPSHIRE
WS Hampshire is a class-leading specialist in vacuum forming operations. We can form acrylonitrile butadiene styrene, high-density polyethylene, high-impact polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate, and most other polymers.
We can also form your choice of materials, with a tolerance of .250”. Our molding processes include deep drawing, pressure forming, and both single-sheet and twin-sheet vacuum forming.
Our processes conform to many different industry standards, with the most common being:
- American National Standards Institute (ANSI)
- American Society for Testing and Materials (ASTM)
- Military specifications (Mil-spec)
- Restriction of Hazardous Substances (RoHS) compliant
To learn more about our vacuum forming processes or to get started on a project, contact us to request more information.