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.
The pressure method relies on air pressure to force the heated sheet of plastic into or around the mold. Compressed air is delivered from the top of the machine with a pressure that ranges from 15 to 300 pounds per square inch, depending on the size of the molded forms. The object forms as the plastic is pressed into the mold.
Mechanical forming is that which uses a double-mold that has a negative bottom half and positive top half. The plastic sheet is placed over the bottom of the mold, heated until it is pliable, and then covered with the top half of the form which squeezes the softened plastic in the particular shape being made. Air vents in the bottom piece provide ventilation.
Other methods of forming are used as well in certain instances. A technique known as twin sheet forming that involves melting and fusing pieces to each other, is used to join together components separated by an empty space. Some plastic parts are formed by way of pressure diaphragm forming which uses pressurized fluid and a vacuum.
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.
The pressure method relies on air pressure to force the heated sheet of plastic into or around the mold. Compressed air is delivered from the top of the machine with a pressure that ranges from 15 to 300 pounds per square inch, depending on the size of the molded forms. The object forms as the plastic is pressed into the mold.
Mechanical forming is that which uses a double-mold that has a negative bottom half and positive top half. The plastic sheet is placed over the bottom of the mold, heated until it is pliable, and then covered with the top half of the form which squeezes the softened plastic in the particular shape being made. Air vents in the bottom piece provide ventilation.
Other methods of forming are used as well in certain instances. A technique known as twin sheet forming that involves melting and fusing pieces to each other, is used to join together components separated by an empty space. Some plastic parts are formed by way of pressure diaphragm forming which uses pressurized fluid and a vacuum.
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 industrial plastic pallets, she suggests you check out her friends www.ptm.com/global.
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