What is thermoforming?
Thermoforming is a generic term for the process of forming plastic parts from a flat sheet using vacuum or pressure. Thermoforming offers close tolerances, tight specifications, and sharp detail. When combined with advance finishing techniques, pressure-forming results in products comparable to those formed by injection molding. Thermoformed plastic parts are used for many applications in our daily lives and have replaced many parts previously manufactured from metal, fiberglass, urethane and wood.
What are the benefits of thermoforming?
Thermoforming is efficient and very cost-effective for the production of many plastic parts. Depending on their size, shape and quantities initial project costs are usually much lower, and lead times to tooling and production can be shorter than other processes. Modifications to design can be achieved easily. Temporary or composite tooling offers an inexpensive short-term test for design and product and market acceptance.
What is Pressure Forming?
This thermoforming process uses positive pressure to force plastic material against the tool surface to achieve finer detail and allow for logos and texturing on the exterior surface of the part. Closer tolerances, better distribution of the material, and lower residual stress are also achieved. This process provides an excellent solution for product detail, reduced lead times and competitive pricing.
What are the benefits of pressure forming?
One of the advantages of pressure forming is a greater reproduction of detail from the mold surface, such as sharp crisp corners and edges, textures, letter and logo reproduction, as well as accurate location of features. This process gives you greater accuracy in part size through tighter control of shrinkage and post forming warpage. This can be accomplished using properly engineered temperature controlled molds. Pressure formed parts typically provide high detail, close tolerance parts in lower volumes at less cost than injection molding.
When and where does thermoforming fit?
Large panels, housings, enclosures, and similar parts are especially well suited to the thermoforming process. Tooling costs for these parts is considerably less than injection molding, which may have prohibitive tooling costs. Parts with features mostly confined to one side of the part are best suited to thermoforming with trimming, fabrication and assembly processes to address features on the uncontrolled surfaces of the part. Many pressure formed parts are developed for housings for medical and electronic equipment and can have EMI/RFI shielding applied on the interior surface to comply with UL electromagnetic emissions requirements.
What thickness of materials do we work with?
We typically deal with materials ranging in thickness from .040” to .500”.
What types of plastics can you thermoform?
Plastics that lend themselves best to thermoforming are; acrylonitrile-butadiene-styrene copolymer (ABS), high impact polystyrene (HIPS), high density polyethylene (HDPE), high molecular weight polyethylene (HMWPE), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate modified (PETG). Many other available materials allow for U/V exposure, UL Flammability, High Temperature, Anti-Static and Anti-Microbial properties.
What kind of cosmetic features can be achieved
Sharp, crisp detail with close tolerances can be achieved. Undercuts, formed in texture, formed in logos, formed in inserts, and custom colors are just a few of the many features that can be accomplished with thermoforming.
What other tooling is required in the thermoforming process?
A vacuum fixture is required when a part must be CNC trimmed. Vacuum fixtures are constructed by taking a reverse impression of the part and mounting this impression into a vacuum box. The trim fixture then holds, under vacuum pressure, each part being CNC trimmed to ensure consistent results.
If other tooling is specifically required in the forming, trimming, fabrication, and assembly of each part, it is designed by our engineers and constructed in house.
What kinds of thermoforming molds are there?
Machined Aluminum, Cast Aluminum, Composite
Machined aluminum molds are typically built for shallow parts with small draw ratios. Plastics Design & Manufacturing uses 6061-T6 aluminum for the construction of these molds, which can be held to very close tolerances. These molds are then mounted on a temperature-controlled base to control the mold temperature during the forming process. Male or female molds and vacuum-form or pressure-form molds can be machined aluminum molds. Molds can be textured and may offer features such as loose cores, pneumatic cores, and inserts.
Cast aluminum molds are cast at a foundry from a machined pattern made of composite material. The temperature controls are cast into the back and sides of the molds at the foundry. Cast aluminum molds typically are built for large parts with large draw ratios and may be male or female and vacuum-form or pressure-form. Features such as texture, loose and pneumatic cores, and inserts are available.
For prototyping and short production runs, cost-efficient composite materials are used for mold construction. These molds produce parts that are to be evaluated for fit, form and function and may be modified to evaluate possible design changes. Composite molds are used in vacuum forming only and have a limited life.