Factory Floor · All
Die Casting: How a Zinc Alloy Pin Blank Is Born
From the factory floor in Shenzhen: how molten ZAMAK 3 zinc alloy is shot into a steel mold on one of our 9 die-casting machines to make a pin blank.
Every cast pin we make starts on this floor. Molten ZAMAK 3 zinc alloy is injected under pressure into a steel mold, holds for a few seconds, and comes out as a blank with the design already raised and recessed. We run 9 die-casting machines at our Shenzhen plant. This is what happens at each one.
The bay runs as one line. Each machine is set up for one mold at a time. A short run of 500 pins and a long run share the same machines; the difference is how long the mold stays clamped in.
The alloy is ZAMAK 3: zinc with a small amount of aluminum, magnesium and copper. It melts at a low temperature compared with brass, flows into fine detail, and takes plating well. We buy it as ingots and melt it at the machine. The pot is kept at temperature all shift; a cold pot gives a rough surface.
The mold is two steel halves. Your design is cut into one of them in reverse. Every raised line on the finished pin is a groove in the mold; every enamel cell is a raised island. The mold also cuts the post location and any text on the back. Once the mold is right, every blank is the same. That is why we spend the proof stage getting it right before steel is cut.
The cycle is clamp, shoot, hold, open, eject. The alloy goes in under pressure so it fills thin lines before it cools. Holding time is short. Then the mold opens and the blank drops or is picked. A blank comes out warm, with a sprue where the alloy entered and a thin flash around the edge. Both are removed at the next station.
Fresh blanks are checked by eye at the machine. We look for short shots (a line that did not fill), cold shuts (a seam where two flows met), and porosity on the face. A blank with any of these goes back into the pot. Only complete blanks move on to trimming and polishing.
What the buyer sees of this stage is nothing, unless something went wrong. A good cast is invisible under the plating and enamel. A bad one shows as a pit, a fuzzy line or a weak post. Our quality checks are described on the factory quality page, and the full process from casting to packing is on the custom enamel pins page.
Book a live video walk-through of the casting bay: email pin@guangdongcs.com or WhatsApp +86 187 1868 4696 (Bella, Export Sales).
Order Facts
- From 100 pcs per design · better price at 500+, best at 1,000+
- Free artwork proof within 2 working days
- Sample 10–14 working days · bulk 30–60 days · rush from 10–15 days
- DDP door-to-door available: duties and taxes included in the quote
- Bella replies within 12 hours