Manufacturing companies that make items such as electronic components, automobile and aircraft parts, packaging, and toys are amongst those which often use a process that molds heated, thin sheets of plastic into the desired shapes. This industrial process is called thermoforming, and it can be done in one of several ways, all of which result in the production of plastic, molded objects.
There are multiple ways to thermoform plastic, but the general process is similar. A plastic sheet is held in place firmly as it's heated to the point of pliability in an industrial oven, it is then stretched over a mold, and cooled down with fans until it is firm. While there are multiple types of plastic that can be used, HDPE or "high density polyethylene" is the most popular. The technique used depends on the type of plastic and size of the mold.
A temperature-controlled vacuum unit is used for the vacuum thermoform technique. The mold is placed in the unit with the sheet of plastic directly above it. As the plastic is heated, the mold is raised until it contacts it directly, as air is pulled out from underneath it, resulting in a airtight connection, that enables the shape to take form.
Pressure forming is a method which implements the use of compressed air that forces the heated plastic sheet onto or into the mold. The air pressure released can range from 15 to 300 pounds per square inch, depending on how large the molded forms used are. The plastic is pressed into the shape of the mold, forming the desired object.
The mechanical technique involves a mold that consists of two halves, a positive upper half and a negative lower half. The sheet of plastic is draped over the bottom part, heated until it is pliable, then the upper part of the mold is lowered onto it, which in turn squeezes the plastic into shape. Air is forced out through vents in the lower half.
Other types include pressure diaphragm forming which fabricates plastic parts using a vacuum and pressurized fluid. Also, twin sheet forming is used particularly for joining two parts that are separated by a hollow space, and it involves first melting two sheets of plastic then joining them together.
This process is often preferred over injection molding by manufacturers since it provides several advantages. For one, thermoform equipment costs a fair deal less than that used for injection molding, and secondly it is much easier and cost efficient to design and build a suitable prototype for this kind of forming.
There are multiple ways to thermoform plastic, but the general process is similar. A plastic sheet is held in place firmly as it's heated to the point of pliability in an industrial oven, it is then stretched over a mold, and cooled down with fans until it is firm. While there are multiple types of plastic that can be used, HDPE or "high density polyethylene" is the most popular. The technique used depends on the type of plastic and size of the mold.
A temperature-controlled vacuum unit is used for the vacuum thermoform technique. The mold is placed in the unit with the sheet of plastic directly above it. As the plastic is heated, the mold is raised until it contacts it directly, as air is pulled out from underneath it, resulting in a airtight connection, that enables the shape to take form.
Pressure forming is a method which implements the use of compressed air that forces the heated plastic sheet onto or into the mold. The air pressure released can range from 15 to 300 pounds per square inch, depending on how large the molded forms used are. The plastic is pressed into the shape of the mold, forming the desired object.
The mechanical technique involves a mold that consists of two halves, a positive upper half and a negative lower half. The sheet of plastic is draped over the bottom part, heated until it is pliable, then the upper part of the mold is lowered onto it, which in turn squeezes the plastic into shape. Air is forced out through vents in the lower half.
Other types include pressure diaphragm forming which fabricates plastic parts using a vacuum and pressurized fluid. Also, twin sheet forming is used particularly for joining two parts that are separated by a hollow space, and it involves first melting two sheets of plastic then joining them together.
This process is often preferred over injection molding by manufacturers since it provides several advantages. For one, thermoform equipment costs a fair deal less than that used for injection molding, and secondly it is much easier and cost efficient to design and build a suitable prototype for this kind of forming.
About the Author:
Genevive B. Mata has over 20 years of professional sales experience, 10 of them directly in the plastic pallets and materials handling industry. On her spare time she works on applied-sustainability projects. If you are interested in plastic pallet containers, she suggests you check out her friends www.ptm.com/global.
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