When selecting a soft material, Ritzema advises manufacturers to work closely with molders and mold builders for optimal results because they have knowledge of how each material performs.
Some of the most common soft materials in the market today include: LSRs, RTVs (room temperature vulcanization silicone), HCR (high consistency silicone rubber), EPDM rubber (ethylene propylene diene monomer rubber) and PVC compounds.
Beyond material characteristics, manufacturers also should pay attention to both material price and the overall cost of a project. Adding new materials to production may require additional tooling costs. Consulting experts, from the molder to the material supplier, will help guide a manufacturer to select the best soft material for their needs.
Each soft material has its own attributes and is best suited for different applications.
When needing a biocompatible option, manufacturers should look at LSR, HCR or soft PVC, he said. For a material with chemical resistant properties, LSRs and RTVs are suitable. They both also have excellent mold flow properties with a low compression set.
For instance, LSRs are resistant to compression sets, keeping its shape where a thermoplastic elastomer eventually would form to the set. The LSR material does not compromise the seal because it will not compress over time.
Beyond its inherent capabilities, the major function of LSRs serve the medical market because it's a medical grade product, whereas other soft materials are not.
“We needed to expand our quality procedures so we could become ISO 13485 registered,” Ritzema said about Rogan's medical grade LSR.
However, if a manufacturer does not need a medical grade product, they should not pay for it, he said. Some of the characteristics to pay attention to when choosing the material is temperatures, tolerances and bonding requirements.
Ritzema said there is no benefit in choosing the most technically advanced product if a less expensive one meets the manufacturer's and end user's needs.