Custom Containers - Thermoform Molded

SUMMARY
Advantages:
Very low tooling costs
Very low lead times
Excellent durability and impact resistance
Can replace serveral pieces into one part
Large parts are easily available
Disadvantages
Non-uniform wall thickness
Not suitable for small intricate parts
Some secondary work will be necessary
Design limitations compared to other processes
Slow cycle times
TYPICAL APPLICATIONS
Commercial containers and dunnage
Pallets
Toys
Agricultural products
Automotive under hood applications
Recreational products

Thermoform molding (or as some refer to as vacuum forming) is a forming process that utilizes low cost and widely available tooling. Lead times are much shorter than injection molding and may offer some flexibility in part redesign. Thermoforming is simply a method of suspending a sheet of plastic over an open mold and heating the sheet until softened. The sheet is then lowered onto the mold and a vacuum is achieved by the usage of multiple holes in the mold, pulling the softened plastic into, or onto, the mold. The softened plastic takes the form of the mold and is usually cooled with the aid of fans. On occasion a “plug” is necessary to assist in forming the plastic sheet into the cavity of the mold.

The molds may be constructed of wood; however, aluminum is the preferred material for high volume production. The low cost of the mold offer the greatest advantage of this process costing only a few hundred dollars for simple parts. An extension of this process offers twin sheets to produce layered parts for dunnage and other products. An inherent disadvantage of thermoforming is the necessity of trimming the excess material from the perimeter of the part, and if openings or holes are desired, these must be drilled with a secondary operation. Another possible disadvantage of thermoforming is the thinning of the material on the corners of the part, especially if the part has a deep draw.

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