Since it became commercially available in the early 1990’s, TPE (Thermoplastic Elastomer) materials have provided a new dimension to the engineering of elastomeric parts in a multitude of applications. While there are a number of possible advantages in designing TPE’s into applications, there are also quite a few drawbacks. When considering TPE as an option, bear in mind that there are several considerations that should be taken into account.
TPE’s offer process advantages that traditional rubber does not. Since TPE’s are processed in the same manner as traditional plastics, the production process is normally more capital intensive, repeatable, and generally produces a shorter cycle time. TPE’s normally don’t require finishing or post cure, so the TPE process is generally going to be leaner with fewer variables. On the down side, the tooling to produce TPE materials will generally be more expensive, and considerably more expensive if the geometry of the part is challenging.
TPE materials may offer economic advantage, depending on the productive throughput of the process. This normally boils down to the number of cavities that can be fabricated for each process. Comparing TPE materials with thermoset rubber, we can look to the following examples for comparison:
Product “A”:
TPE Process: 4 Cavity mold, 30 second molding cycle, no secondary processing required
4 Cavities X 30 second cycle = 8 parts per minute (480 per hour)
Rubber Process: 24 Cavity mold, 3 minute molding cycle, secondary processing required
48 Cavities X 20 cycles per hour = 12 parts per minute (960 per hour)
Even with required secondary processing (finish/post cure), the higher productive throughput means the rubber process will offer considerable economic advantage.
Product “B”:
TPE Process: 8 Cavity mold, 30 second molding cycle, no secondary processing required
8 Cavities X 30 second cycle = 16 parts per minute (960 per hour)
Rubber Process: 15 Cavity mold, 3 minute molding cycle, secondary processing required
15 Cavities X 20 cycles per hour = 3 parts per minute (180 per hour)
Although the rubber process includes almost twice the number of cavities, the TPE process will likely offer substantial economic advantage.
There are dozens of other considerations which could impact processing considerations and resulting economic advantage, and Real Seal engineering and design support has helped hundreds of customers make this determination.
Although TPE materials have improved dramatically in the last 20 years, they are still generally inferior in terms of physical properties. All else being equal, rubber materials will normally have better tensile strength, elongation, and especially compression set. TPE’s offer environmental advantages, as their thermal bonds are reversible, so they can be widely used as “filler” or regrind in a multitude of applications.
As technology continues at a blistering pace, Real Seal technical staff remain on the front of the wave, and are available to help support material and design engineering for elastomeric products.
