process plastics Vacuum Forming

This process page is kindly sponsored by
Formech International Ltd.
For more information please e-mail ... sales@formech.com

Vacuum Forming

Virtually all thermoplastics can be supplied as sheet and vacuum formed. The more commonly used materials are listed below.

Typical Materials Used

Acrylonitrile Butadiene Styrene	ABS
Polyester Copolymer	PETG
Polystyrene	PS
Polycarbonate	PC
Polypropylene	PP
Polyethylene (sheet and foamed sheet)	PE
Polyvinyl Chloride	PVC
Acrylic	PMMA

Typical Products Produced

Baths & Shower Trays	Yoghurt Pots
Ski-Boxes	Boat Hulls
Machinery Guards	Vehicle Door Liners
Refrigerator Liners	Sandwich Boxes
Parts of vehicle cabs	Exterior Shop Signs

Overview

Thermoforming is one of the oldest and most common methods of processing plastic materials. Vacuum formed products are all around us and play a major part in our daily lives.
The process involves heating a plastic sheet until soft and then draping it over a mould. A vacuum is applied sucking the sheet into the mould. The sheet is then ejected from the mould. In its advanced form, the vacuum forming process utilizes sophisticated pneumatic, hydraulic and heat controls thus enabling higher production speeds and more detailed vacuum formed applications.

Nature of Use and Limitations

Vacuum forming offers several processing advantages over other forming processes. Low forming pressures are used thus enabling comparatively low cost tooling.

Since the process uses low pressures, the moulds can be made of inexpensive materials and mould fabrication time can be reasonably short. Prototype and low quantity requirements of large parts, as well as medium size runs therefore become economical.

More sophisticated machines and moulds are used for continuous automated production of high volume items like yoghurt pots, disposable cups and sandwich packs.

Unlike other thermoplastic forming processes, where powder or resin are the starting point, vacuum forming uses extruded plastic sheet. With vacuum forming a secondary process may be required to trim the formed sheet to arrive at the finished part. The trimmed waste can then be re-ground and recycled.

Vacuum Formings produced
using Formech Machines

The Process

Clamping
The clamp frame ensures the plastic sheet is held firmly in place during the forming process.

Heating
Radiant heaters are normally used to heat the sheet which has been positioned over the aperture of the vacuum forming machine. For thicker sheet both surfaces may need to be heated and more sophisticated machines allow this. Heaters move into position both above and below the sheet.

Pre-stretch
Is used to achieve "even" wall thickness. Air is introduced to blow a small "bubble" and the mould is then raised into the pre-stretched sheet.

Vacuum
A vacuum is applied, the sheet is drawn into intimate contact with the mould and the mould detail is picked up.

Plug Assist
Where a deep draw is required a top "plug" may be used to push material into the mould during the forming process.

Cooling and Release
The material is allowed to cool. The cooling process may be shortened with blown air or even a fine water spray. The moulding may then be released from the mould by introducing a small air pressure.

Finishing
After moulding, any mould finishing may be performed, trimming, cutting, drilling, polishing, decorating etc.

... For a more detailed Process Description Click Here

Links

Photograph Gallery of
Vacuum Formed
applications &
products...

Animation of the Vacuum
Forming Process...

Photo Sequence of the
Vacuum Forming Process...

Vacuum Forming Machines
and Moulds for Educational
Study Purposes...

About Formech International Ltd

Formech recognise the importance that plastics play in our society today and have been manufacturing and selling thermoforming equipment worldwide for over twenty years. The Company has provided industrial and educational users with a wide range of high precision engineered, easily maintained and cost effective vacuum forming machines to turn plastic sheet into innumerable shapes, objects and commercial products.

Formech's commitment is to support their customers at the forefront of technological change in implementing their product ideas. Through prudent monitoring of the industry and a constant awareness of customer requirements Formech has provided the vacuum forming solution to over 6000 customers worldwide.

Formech strive to ensure our machines and support services continue to meet the ever growing and rigorous demands of the international market. That combined with an innovative approach ensures Formech is now firmly established as the most popular producer of manual, semi and fully automatic thermoforming machines on the market.

This process page is kindly sponsored by
Formech International Ltd.
For more information please e-mail ... sales@formech.com

View printer friendly version of this page