Vacuum Forming


Also found in: Dictionary, Wikipedia.

vacuum forming

[′vak·yəm ′fȯrm·iŋ]
(engineering)
Plastic-sheet forming in which the sheet is clamped to a stationary frame, then heated and drawn down into a mold by vacuum.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Vacuum Forming

 

a method of molding items from plastic sheets. During vacuum forming the sheet materials up to 2 mm thick, based on thermoplastic polymers, are secured to the mold, heated to the point of softening, and then shaped by the action of atmospheric pressure, and a vacuum on the order of 10 kilonewtons per sq m (100 mm Hg) is simultaneously produced in the cavity created by the sheet and the surface of the form.

Articles with a great depth of drawing are produced by the positive method of vacuum forming (the material is formed on the surface of a convex punch mold); articles with a lesser depth are produced by the negative method (the material is pulled into a depression in a matrix mold). Optically transparent parts (for example, airplane cabin windows) are obtained by so-called free vacuum forming, in which the hemisphere that forms as a result of a pressure drop does not touch the walls of the chamber (in this method a mold is not necessary); because of this, the finished article has a smooth surface.

The advantage of vacuum forming as opposed to other methods of forming items from a sheet is the low specific pressure required to produce molds from easily processed materials (gypsum, wood, aluminum, and so on). Various containers, hemispherical items, refrigerator parts, and such are produced by means of vacuum forming.

REFERENCES

Bratsykhin, E. A., S. S. Mindlin, and K. N. Strel’tsov. Pererabotka plasticiheskikh mass v izdeliia. Moscow-Leningrad, 1966.
Bernhardt, E. (compiler). Pererabotka termoplastichnykh materialov. Moscow, 1965. (Translated from English).

R. V. TORNER

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Allow them to explore on their own what vacuum forming is, what it can be used for, and how it relates to thermal technology as well as the food industry.
As with commercially available thermoplastics, biopolymers obtained in this way and containing between 5-30% Vinnex can easily be processed by injection molding, extrusion, vacuum forming, thermoforming and calendering.
DKI Form, based in Spentrup, Denmark, is the country's second largest vacuum forming company.
The company, which provides vacuum forming, moulding, prototype production and engineering expertise opened for business earlier this month as Thermotec Plastics.
The provider of vacuum forming, PU moulding, prototype production and engineering expertise has now opened its doors as Thermotec Plastics Ltd.
For example, the bathtub (an essential part of the hydro-spa system) is produced in two stages--in the first stage the shell is produced by vacuum forming, and in the second stage the shell is strengthened by adding a glass fiber epoxy layer on one side.
Twin-sheet thermoforming uses both vacuum forming and pressure forming.
Applications include plastic extrusion, vacuum forming and blow molding, packaging equipment, heat treating and other uses in which real time multi-zone temperature control is critical.
These units are ideally suited for a wide range of applications, including health care, pharmaceutical, packaging, vacuum forming, CNC machining, and removing contaminants and liquids.
The machines range from a semi-automatic belt system to an automatic rotary fill and seal unit, with or without gas flushing or vacuum forming. A bag-forming system can also be supplied to save on packaging costs; alternatively, a denester for pre-made pouches can be fitted.
But instead of outsourcing the vacuum forming process as many of its competitors have done, Blackhawk runs its own high-speed vacuum forming machines which are monitored closely by its engineers.
In vacuum forming, a thermoplastic sheet is heated to its softening temperature as it is held in a clamping device.