Friday, January 31, 2014

The Steps Involved In Custom Plastic Thermoforming

By Serena Price

Thermoforming involves heating thermoplastics extruded from pellet forms until they reach a pliable state. The sheet is usually removed from the heat once it reaches the forming temperature. A mold then enters the softened sheet before it is sealed on the edge. Thereafter, a vacuum is applied to eliminate the air that might have been trapped between the sheet and the mold. There are various things done in custom plastic thermoforming before the final product comes out according to the wants of a client.

The sheet is usually pushed by the atmospheric forces, which result to cooling both internal and external parts of the sheet. The next step involves separating mold from the mold, trimming, completing the finishing per print, and the readying it for shipping. Cast aluminum molds are highly recommended for thermoforming.

Aluminum offers the best heat transfer which enhances accurate control of the cycle times, part war-page, and part shrinkage. In order to achieve trimming and quality control, it is essential to ensure consistency in the forming process. Molds can be made in single or multiple cavities, though it depends with the size and geometry. They can also be categorized under either female or male groups.

The female and male groups are determined by the aesthetic requirements, dimensional needs of the client, and compatibility with the rest mating parts in the assembly. The material used for the process can come in various types of grains and placed on only one side of the sheet. The sheet, however, is normally formed with the smooth side against the mold. When the sheet is formed with the grain on the mold side, it can be washed away to leave an unpleasant display.

Textured molds normally have several uses. For instance, they can be used with grains on both sides thereby enhancing the grain or the part that must have a grained finish on a female mold. Unlike other mold forms, textured molds are often expensive.There are several techniques used in thermoforming.

Some of the most common techniques include; pressure forming, twin sheet forming, snapback forming, billow forming, and plug assist forming. Each of the aforementioned techniques are normally used in line with several factors that influence them. For example, the pressure forming is usually used to form the appearance of a structural foam part or injection mold with a small piece of the molding material.

The above method is the most preferred technique for thermoforming because it results with the highest details of the process. Just like all the other types, pressure forming begins with heating the sheet plastic and forming it by exerting pressure on the plastic on top of a mold. The process requires large air pressure amounts in order to achieve the desired product.

Despite being one of the most expensive forms, pressure forming is suitable for production of items with exceptional quality. Examples these include ABS, other thermoplastic materials, Acrylic PVC, and Polycarbonate. Pressure forming technique is also suitable for use in special cases. Some of which include the formation of clear and sharp molded-in details such as texture, logo or label recess. The best person to handle your custom plastic thermoforming projects is a qualified and experienced professional.

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