The Thermoforming Process - Vacuum / Pressure Forming

VTI has manufacturing engineering expertise.

VTI has both In-Line Equipment (for thin film) and Shuttle Machines (heavier gauge).

VTI produces parts from all thermoplastic materials; both thin film and heavy gauge stock, via the thermoforming process. Thermoforming is a method of shaping plastic sheet to conform to the contours of a mold through the use of heat and pressure. Vacuum forming uses a negative pressure between the sheet and the mold. Pressure forming uses a positive pressure on the opposite side of the sheet and a negative pressure between the sheet and the mold. With all thermoforming, dry sheet is heated to a controlled softening temperature, stretched to conform to the mold contours and cooled to the temperature at which the part becomes rigid and maintains the desired shape. The formed part is then trimmed to eliminate edges and fabricated into the final configuration.

Each step in the forming process is vital to the quality of the finished part. Sheet quality, heating processes, forming paramaters and cooling conditions must be monitored and controlled to obtain quality parts. Wall thickness variation, surface appearance and material physical properties are dependent on accurate process control to achieve the desired final product.

Thermoforming accommodates a wide range of sheet thickness' from thin gauge used to produce packaging containers to heavy gauge sheet for large parts such as recreational vehicle tops and boat hulls. Intermediate gauges are used for the majority of applications such as shipping and handling trays, displays, instrument housings and many others.

VTI has both thin film and heavy gauge capability to service our customers' needs. Some of the advantages of thermoforming, based on many years of industry experience, are as follows:

VTI uses aluminum molds almost exclusively to provide thermal uniformity and long lifetimes. Thermoform tooling is relatively inexpensive compared to other plastic manufacturing processes. As little as 1/10 the cost of other process molds can be expected with thermoforming tooling. Also, the life expectancy of thermoform tooling is extremely long due to the no-wear process. Molds can be either male or female as shown below. Tooling design and manufacture is performed in-house by VTI to assure complete control of customer requirements.