Rubber Mold

Rubber Mold

the way we actually do it at ABIS when the customer needs 50 to 300 pieces next week and the steel tool is still two months out

Most of the time the master comes from a quick CNC aluminum block. Sometimes the customer just hands us a 3D-printed part that’s already pretty close, we sand it, spray a couple of coats of release, and call it good enough. We build a simple plywood box around it, stick the master to the bottom with a bit of clay so it doesn’t float, and that’s the casting frame. Nothing fancy.

How we pour the silicone in the shop

Silicone is almost always a Chinese platinum-cure 40 Shore A, 10:1 mix. We weigh it on a cheap digital scale, mix by hand for three minutes, then throw the cup under the vacuum bell until the bubbles stop climbing – usually 90 seconds. Pour slow from one corner so the air can escape. If we’re in a hurry we put the whole box on a vibrating table for another minute. Cure overnight in the corner of the shop where the temperature stays around 25 °C. Next morning we take a cutter and slice the block open along the line we drew the night before. Pull the master, spray a little more release into the cavity, clamp the two halves between two scrap aluminum plates with four bolts and a couple of dowel pins. Done.

How many parts you really get

One mold normally gives us 25 to 70 clean pulls. Flat gaskets with no undercuts can go past 80. Anything with thin ribs or sharp corners starts tearing around shot 30 and we make a new one. We tell customers up front: if you need more than 80 pieces, think again about soft tooling.

What resins we actually use every week

We pour mostly two-component polyurethanes. For soft seals we use a 50 A that feels almost exactly like production TPE. For stiff housings we have an ABS-like 80 D that machines okay if they need to drill holes later. If the part sees temperatures above 120 °C we switch to a slow epoxy – smells terrible, cures in 24 h, but it survives.

Real job example – German transmission seal

Last year a German automotive Tier-2 showed up with a transmission seal that had eight tiny undercuts. Steel tool quote was nine weeks and €28 000. We made the rubber mold on a Tuesday, poured the first ten samples Wednesday morning, and the guy flew back to Stuttgart the same afternoon with parts in his carry-on. Later they ordered 180 pieces in three batches while waiting for the P20 tool. We charged them $620 for the mold and $6.80 a part. Everybody happy.

Real job example – medical silicone buttons

Another job was a batch of 44 overmolded silicone buttons for a medical device. The insert was a small PC board with LEDs. We froze the brass threads into the mold with a little wax, poured clear 50 A silicone around them, cured, and the buttons came out ready to click. Took us four days from CAD to finished samples.

Money talk – what it actually costs here

Cost-wise it’s simple: a rubber mold here costs between 350 and 800 USD depending on size. Steel starts at 12 000 USD and up. If the quantity stays under 200 pieces nobody even discusses steel anymore.

The three rules we beat into every designer

Keep walls above 0.8 mm or the rubber tears, put half a degree draft wherever you can, round every inside corner to at least 0.2 mm or you’ll hate life after shot 15. That’s it.

That’s how rubber molds work in the real world – quick, dirty, cheap, and usually good enough to get the product into the first real tests or even low-volume sales. When the order finally jumps to thousands we hand the master pattern to the tool shop and wave goodbye. Until then, silicone keeps the project moving.

ABIS Mold Technology Co., Ltd. is one of the most famous rubber mold manufacturers and suppliers in Shenzhen, China. Welcome to wholesale high quality rubber mold from our factory.