1.What is vacuum forming?
Vacuum forming is one of the common methods of processing plastic materials. The main principle is that the flat plastic hard sheet is softened by heating, adsorbed on the surface of the mold by vacuum, and formed after cooling.
Vacuum forming originates from the 1930s and yet it remains increasingly relevant today. This process is a simplified version of thermoforming. It can be used to form plastic into permanent objects or recyclable products such as display stand, 3D wall panels, television back covers, seedling tray, plastic trays and so on. Normally draft angles are present in the design of the mold (a recommended min of 3°) to make sure the products can easily release from the mold.
2.Two types of vacuum forming mold.
A good mold can make the whole product in smooth production, which says the mold is the first baby when we produce a vacuum forming product.
There are two types of mold we always used: Male mold and Female mold. Generally speaking, the surface of the male mold is convex, and the female mold is concave.
When we using a male tool, the visible surface of the formed part is usually the top surface and therefore the thickness of the plastic sheet tends to hide some of the imperfections on the tool surface, producing a more attractive surface finish. Male tooling costs are also usually less expensive than those for a female tool. Compared to a male tool, a female tool often reduces the possibility of webbing too and its closer spacing can give you cost savings in material.
3.How we produce a plastic product through vacuum forming?
Step by step, the process could be making a mold, vacuum forming processing, CNC drilling and cutting, burring and Quality testing finally.
Generally, professional mold makers are hired to evaluate 3D drawings. Aluminum materials can be used to make molds after the dimensions and draft angles of the drawings are confirmed.
Then we can go into the vacuum forming process, the main process is: Firstly, put a sheet of plastic placed in an open frame and clamped into place. Secondly, heated the hard plastic sheet to soft through a heat source, the mold is contacted with the softened material, and the air is extracted from the bottom of the mold through the suction hole on the mold to form a vacuum environment. Thirdly, cooled molded material. Finally, we can release the molded product from the mold and frame.
After vacuum forming, we can use CNC machines for doing the precision treatment on the products. All the processes are controlled by the computer. The CNC machines can be 3-axis CNC machines and 5-axis CNC machines (360 degree process).
When the previous work is done, it is necessary to burring the edge of the product to prevent the damage from sharp edges left behind by the CNC process.
4.The common application of vacuum forming products.
Vacuum formed parts always are single component parts. Such as plastic tray, plastic housing, plastic enclosures, plastic television back cover, plastic seedling tray, medical parts, hydroponics fodder tray and so on. These products are often replacements for sheet metal or fiberglass that need to be light but durable and have good strength relative to weight.
Here are some materials we always used to make vacuum forming plastic products: ABS (Acrylonitrile Butadiene Styrene), PETG (Polyester Copolymer), PS (Polystyrene), PC (Polycarbonate), PP (Polypropylene), PE (Polyethylene), PVC (Polyvinyl Chloride), Acrylic also called PMMA. These materials are all recyclable and can be customized with different surfaces. Meanwhile, the material can be UV resistant, V1/V0 nature, impact resistant and so on.