Discover what it is thermoforming and vacuum thermoforming. Learn how heating thermoplastics allows you to create precise shapes in a variety of industries.
Vacuum is a technological process, during which products of specific shapes are formed from flat plates fixed in special frames heated to a certain temperature characteristic of a given thermoplastic material.
The molding of the desired shape is carried out when the plastic is in a highly elastic state. A vacuum is generated between the heated plate and the tool (mold), and under the influence of external pressure, a deformation takes place that reproduces the shape of the mold.
The final stage of the process is the solidification of the resulting shape during cooling and mechanical processing to obtain the final shape. Vacuum thermoforming is a very popular process for the production of plastic packaging and medium-sized and large parts. Vacuum thermoforming is an excellent alternative to injection molding, especially for medium-volume production, which means significant cost and time savings. Depending on the geometry of a component, its intended function and requirements for wall thickness distribution and appearance. Geo Globe Polska uses several vacuum deep-drawing processes:
a) positive forming
b) negative forming
c) positive negative forming
d) double-sided forming into two shapes
e) vacuum pressure forming
f) twin-sheet forming (TWIN SHEET)
What is positive forming?
With vacuum positive forming, the mold cavity is convex.
In the first phase, there is an initial stretching of the material, which is in a highly elastic state and fixed on the edges of the pressure-vacuum chamber; in the second phase, the mold cavity moves in a direction perpendicular to the material until it is initially covered by the material. The exact molding of the manufactured object occurs under the influence of the pressure difference on both sides of the material, caused by the rapid removal of air through the ducts from the space between the material and the socket.
Negative forming
The material (sheet) in a highly elastic state is trapped between the upper and lower frames, the mold with the concave cavity is moved towards the lower frame until it is sealed. Rapid removal of air from the cavity through the channel creates a pressure difference on both sides of the material, resulting in deformation of the material that reproduces the shape of the mold.
Positive/negative forming
The material is trapped in a highly elastic state between the upper and lower frames, the material is pre-blown, the balloon is rotated downwards by a plunger, the mold is moved to the lower frame until it is sealed, a vacuum pump is switched on to remove air between the material and the mold, after a certain cooling time the plunger is driven off and the part is demolded.
Double-sided forming into two shapes
Vacuum double-sided according to the technology developed by GGP is realized by using a second mold attached to a punch moved by servomotors.
A sheet in a highly elastic state is enclosed between the upper and lower frames, the material is pre-blown, the balloon is rotated down through the upper mold attached to the punch, the lower mold is moved to the lower frame until it is sealed, the upper mold pushes the material into the lower mold, a vacuum pump removes the air between the material and the two molds through vacuum channels, and after a certain cooling time, the punch is driven off and the part is demolded.
Vacuum pressure thermoforming
Vacuum pressure thermoforming using the technology developed by GGP is carried out with a punch moved by servo drives.
It is used to form parts with complex geometries, especially with small radii of curvature.
The heated thermoplastic material in a highly elastic state is trapped between the upper and lower frames, the mold is moved to the lower frame until it is sealed, the punch presses the material into the mold, a vacuum pump is switched on which removes the air between the material and the lower mold through venting channels, compressed air is supplied to the upper mold to support the mold cavity formed by the material. After a certain cooling time, the punch is removed and the part is demolded.
In twin-sheet thermoforming, two panels are formed and welded in a single thermoforming process.
In this process, the two panels are heated to a highly elastic state. After the sheets are pressed together by both molds, the sheets are welded together. Rapid removal of air from the cavity through the channel creates a pressure difference on both sides of the material, which leads to deformation of the material that reproduces the shape of the mold.
Vacuum thermoforming process
Depending on the product requirements (expected price, geometric tolerances, mechanical strength, chemical resistance, resistance to atmospheric ageing, transparency), extruded sheets made of various thermoplastics are used in vacuum thermoforming. Some thermoplastics must be pre-dried before processing. These include: ABS, ASA, PMMA, PA, PC i PET. The temperature and drying time depend on the type and thickness of the plastic.
In addition, the outer surface of the thermoformed panels can be protected with a protective film, which is only removed once the finished product has been installed in its final location.
Depending on the intended use, the panels can have fire-retardant, conductivity-enhancing or antibacterial additives in the outer layer of the panels from which the sanitary elements are formed.
An important advantage of this technology is that high-quality coextruded sheets can be used, the core of which consists of recycled materials and the visible surfaces after thermoforming consist of original materials that are dyed in the desired color and are resistant to environmental influences.
Thermoforming at a glance. Learn about thermoforming processes at Geoglobe.
Learn about the most important aspects at a glance: thermoforming i thermoforming of plastics, shown in practical, concise terms that will allow you to quickly assess the application of this technology.
Vacuum thermoforming involves heating a flat sheet of thermoplastic material to a highly elastic state, then molding it on a mold by removing air and fixing the shape during cooling. The process is completed with machining, trimming and possible finishing.
You have several methods to choose from: positive molding, negative forming, positive-negative formation, two-sided forming, vacuum-pressure forming and two-plate thermoforming (TWIN SHEET). Each method serves a different purpose, from simple packaging to items with complex geometries and high aesthetic requirements.
In preparation for the thermoforming of plastics, keep in mind the choice of material: ABS, ASA, PMMA, PA, PC and PET may require pre-drying. You can use coextruded sheets with a recycled core and high-quality outer layers, as well as fire-retardant, antibacterial or conductivity-enhancing additives.
Advantages that should interest you You: lower cost and shorter start-up time than injection molding for medium-volume production, ability to protect the surface with a protective film, ease of molding large-size parts, and flexibility in the selection of materials and functional additives.
Practical tips for your projects: design molds with wall thickness distribution in mind, consider air extraction ducts for better part representation, test heating and cooling parameters, and for geometrically complex parts consider vacuum-pressure or twin sheet technology. Geoglobe As a leader in this field will help you!
Follow us on social media
You may also be interested in:
- Thermoformed materials in electric cars - applications in lightweight components and interiors
One of the biggest design challenges of electric cars is vehicle weight. In many EV models, the battery pack can account for as much as 20-30% of the vehicle's empty weight, making many electric cars heavier than their combustion counterparts. Weight differences within the same model lineup can reach several hundred kilograms, depending on battery capacity and configuration ... - ABS concrete molds - how did we reduce the cost of production and increase the efficiency of precast products?The production of precast concrete products is all about repeatability, durability and time. Any mold inaccuracy means material losses, delays and additional costs. Check out how, at Geo Globe Poland, we designed recycled ABS molds that streamlined batch production and realistically reduced costs on the client's side. Who was the customer? The client was a company in the foundry and precast concrete industry, ...
- Thermoforming - process and applicationDiscover what thermoforming and vacuum thermoforming are. Learn how heating thermoplastics allows the creation of precise shapes in a variety of industries. Thermoforming is a technological process during which products of specific shapes are formed from flat plates fixed in special frames-heated to a certain temperature characteristic of the thermoplastic in question. Forming of the desired shape is carried out when, ...
- Plastic packaging sewn to sizeAre you looking for tailor-made plastic packaging because current solutions are starting to limit your process? Or are you facing a new product implementation and want to sort out packaging, transportation and storage from the design stage? Whether you're just planning an implementation or want to improve an existing solution, it's worth looking at plastic packaging more broadly than just through the prism of ...