PDI Plastics puts a lot of focus on the front end of the product realization process. We work closely with our customers to optimize their product design, tooling and production process to:
- satisfy their application and intended use
- achieve the desired aesthetics
- produce highly repeatable parts
- minimize total production cost
In order to best quote on your requirements we would appreciate the following information:
- Part shape and basic dimensions
- Expected annual demand
- Material required (if known)
- Finish required
- Special criteria (medical, food contact, ESD etc.)
- Labeling and packaging requirements
We can work from a simple sketch, 2-D drawings, all the way up to a full 3-D model.
One of the first things we will do on your project is determine if the part is suitable for thermoforming. If we feel that it is then we look closer at the design. We might suggest modifications to make the part better to form or trim. Such modifications might include increasing radii of corners and increasing draft angles on vertical surfaces, things that typically improve the formability and strength of the part.
Knowing the limitations of particular manufacturing processes is critical. If a part is not suitable for thermoforming (or fabrication) we will suggest options that you might want to look consider.
We can work from multiple different 3-D Model file formats including:
PDI Plastics has experience in a wide range of materials and will help the customer decide what is appropriate. One feature of thermoforming is that once you have a mold, different types of material can generally be used on that mold without modifying the mold. Materials we work with include ABS, HIPS, PETG, HDPE, Kydex and Boltaron.
For thermoformed parts generally two types of tooling are needed, a mold to form the part and some type of trimming fixture.
PDI Plastics designs and produces nearly all of the molds that our customers need. Each mold is designed using the 3-D model of the part and adjusting dimensions for plastic shrinkage. We CNC machine most of the molds directly from aluminum plate. This is more accurate than the conventional method of pouring a cast aluminum mold, where tolerances and shrinkage allowances at the different stages can combine to make a significant difference to the formed part dimensions. Machined molds are also quicker to produce with fewer steps and being produced all in house.
We do sometimes make resin or even plywood molds for product development projects but prefer to use aluminum and convert the prototype mold into a production mold as the project progresses.
Once the prototype mold is ready it is mounted on a base and used to form the first parts. These sample moldings are checked dimensionally and then trimmed to final dimensions. Trimmed samples are then sent to the customer for review and approval. Any issues or concerns are discussed and addressed, modifying the design and mold if need be. Once the customer approves the mold is set up for full production runs. Additional cavities are added for multi-cavity molds
At PDI Plastics we put a lot of focus on getting the part design, tooling and manufacturing process optimized so that consistent, high quality, cost effective parts are produced. Time is well spent at the front end of a project getting everything optimized so that production runs smoothly. Weak designs and manufacturing processes generally result in product variation and high scrap rates. Considerations include:
- Balancing the molding and trim times for example by making multi-cavity tools. The molding time tends to be longer than the time to trim one part, but trimming 2, 3 or 4 parts might equal the molding time.
- Making the mold base bigger than it needs to be so there is more plastic sheet over which to spread the stretching during molding which helps produce more consistent wall thicknesses across the part.
- Increasing draft angles and radii so that the corners of the part are thicker, stronger and less likely to crack.
- Advising to use a stronger material such as ABS even though cheaper polystyrene might work.
- Adding ribs or other features that strengthen the part.