Ask DAAV: rubber and plastics engineering basics

These short examples were answered by DAAV, COi’s AI assistant, and checked against public engineering references. They are general information, not a material specification, design approval or performance guarantee. Final choices depend on your application and review by the engineering team.

什么是 压缩永久变形?

General information: Compression set is the permanent deformation a rubber part keeps after it is squeezed for a set time at a set temperature and then released, usually reported as a percentage of the original deflection.

What does Shore A durometer measure?

General information: Shore A durometer measures the resistance of a rubber surface to indentation by a spring-loaded pin, which is how the hardness reading is produced.

Why does the exact fluid and temperature matter when choosing rubber?

General information: The exact fluid and temperature matter because rubber compounds swell, harden, soften, or degrade differently depending on the chemical and the heat they are exposed to, so a compound that works in one fluid at one temperature may fail in another.

What is a parting line on a molded rubber part?

General information: A parting line is the seam or witness line left on a molded rubber part where the two halves of the mold meet, and it is often a small raised ridge of flash that may need trimming.

Why should critical dimensions be identified on a molded rubber drawing?

General information: Critical dimensions should be identified on a molded rubber drawing so the manufacturer knows which features affect fit or function and must be controlled most closely, since rubber is flexible and shrinks or varies during molding, which makes clear priorities essential for quoting and inspection.

How does a thermoplastic elastomer differ from a thermoset rubber?

General information: A thermoplastic elastomer softens when heated and can be remelted and reprocessed, while a thermoset rubber forms permanent crosslinks during curing and cannot be remelted once set.