Injection Molded Rubber Door Stops

Rubber door stops

  • Industry: Material Handling Industry
  • Application: Used on floor to hold door open
  • Process: Injection Molded
  • Material: EPDM
  • Highlights: 8 different colors available

Molded EPDM Rubber

Molded EPDM rubber is ideal for door stops because of its ability to resist harsh conditions. Also recommended for its ability to stabilize color and resist heat. EPDM is an economical choice because it offers the advantages of neoprene, at a lower cost. EPDM is also widely used in the automotive industry because it is ozone resistant, temperature resistant and has an attractive appearance.

We do not recommend the use of EPDM for applications that involve petroleum derivatives. Mineral oils and solvents can cause an adverse reaction when used with EPDM. EPDM is also not recommended as an electrical insulator.

Rubber Injection Molded Door Stops Process

Rubber injection molding was first used in the mid-1960s and was based on the plastic injection molding process.  The key difference between plastic and rubber injection molding is that in rubber requires significantly higher pressure to cure the rubber thus leading to longer cure times.

The process starts with the tooling, a rubber injection mold typically with multiple cavities.  The mold consists of a nozzle plate, runner plate, cavity plate, and a base plate with a post-molding ejector system.  The rubber compounds and additives are mixed to create rubber stock.  The stock is formed into continuous strips of uncured rubber stock approximately 1.25″ wide & .375″.

The continuous strip is automatically fed from a hopper into the injection molding machine into a heated barrel, conveyance channel, which softens, plasticizes the rubber.  The stock is then pushed by a large auger, screw-type plunger through the injection nozzle. After flowing into the nozzle plate, the rubber is routed through the runner plate, through the gates, and then into the mold cavities.

When the cavities have been filled the heated mold is kept closed under pressure. The temperature and pressure activate the cure of the rubber compound, vulcanizing it.  Once the rubber reaches and required level of cure, it is allowed to cool and reach a solid state within the mold. The molds open and parts are removed or ejected and ready for the next cycle.

In cases where rubber injection molding is used to encapsulate metal components with rubber or bond rubber to metal, the components are loaded, either by hand or using a loading fixture, into the heated mold cavities. The mold is then closed and the injection molding cycle can begin. After curing is completed, the mold is opened and parts are removed. The cured rubber in the runner is removed, cured rubber in the injection nozzle is purged, and the mold cavities are cleaned in preparation for the next molding cycle.

Rubber Injection Molding Advantages

  • A mid-to-high volume, efficient process
  • Full automation is available
  • Provides high-tolerance, precision rubber molded products
  • The best rubber process for consistency and repeatability
  • Allows for molding of complex geometry
  • Ideal for rubber to metal bonding,  insert molding and over-molding
  • Color molded rubber
  • Lower unit cost
  • Eliminates preforms and preform labor cost
  • Flashless molding / flashless tooling / eliminating secondary trimming
  • Rapid cavity filling
  • Reduced cycle time
  • Minimal material waste

Rubber Molding Capabilities

Different molding processes have different strengths.  That’s why Qualiform offers quality custom rubber compression moldingcustom transfer moldingcustom rubber injection molding, and rubber to metal bonding .  Our experts help you match the best process to your project.

Our technical staff is ready to assist you with all your custom rubber molding needs.