Video: How are rubber keypads made?

Hi, I’m Mike Ryan, the CEO of RSP.

Have you ever made a waffle? You needed a waffle iron, heat and pressure to make a delicious breakfast.

Now, imagine that same process, but use a 250 ton waffle iron the size of a small mini-van.

While silicone can be molded by injection molding -- using liquid silicone rubber, most keypads are compression molded in a giant waffle iron.

Compression molding is much more efficient than injection molding, resulting in a lower cost per unit which means it is better suited for mass production.

Some silicone tools have 10, 50, 100 or even 200 cavities. This means every couple minutes you can produce 100 or 200 parts, while Injection molding is limited to only a couple cavities.

So how does compression molding work?

  • Silicone, prior to vulcanizing in the tool or machine, is similar to Play-doh which is pliable
  • Color is added to the silicone to match your requirement
  • It is rolled out into sheets
  • Using software, we determine exactly what amount of silicone is required to mold your part
  • It is carefully cut and weighed
  • Then cut pieces, in 1 or more colors, are placed strategically in the tooling cavity to ensure the right amount fills the cavity
  • The operator cycles the machine, the tray slides into the machine, heat and pressure are applied and the rubber is vulcanized
  • Cycle times vary from 30 seconds to 10 minutes
  • The pressure releases, the tray slides out
  • The operator, using gloves and air hose, carefully removes the silicone keypads from the tool
  • Process repeats itself 24 hours a day 6 days a week at our facility

This is obviously a very simple explanation. There are lots of other steps and procedures depending upon what is required.

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