Silicone earplugs look simple. They're not. The difference between a 90-night reusable plug and a one-use rejected sample comes down to material grade and three specific process controls. Here's the manufacturing flow at SIAN, plus where lower-tier suppliers cut.
Step 1: Raw silicone qualification
Medical-grade silicone for earplugs is typically LSR (Liquid Silicone Rubber) or HCR (High-Consistency Rubber). The grade we use is FDA food-contact compliant, meaning it's been tested per FDA biocompatibility guidelines for skin contact applications. Each batch of raw resin ships with a Certificate of Analysis from the supplier; we verify hardness (Shore A 5-15), tensile strength, and elongation before it goes on the line.
What cheap suppliers skip: the COA verification. A "silicone" earplug from a brokered material can be 30-50% filler (calcium carbonate). It still feels silicone-ish — until the user gets a skin irritation after a week.
Step 2: Compression moulding
The raw silicone is loaded into a steel mould heated to 180°C. Pressure of 8-12 tons compresses the silicone into the mould cavity. Curing time: 60-90 seconds. Each mould produces 8-16 earplugs per cycle depending on cavity count.
The mould itself is the most expensive piece of equipment per product. A new earplug shape requires roughly 21 days of tooling time and $3,000-8,000 in mould cost depending on cavity count. We amortize moulds across high-volume OEM runs.
What cheap suppliers skip: mould refresh. After 100,000 cycles, the mould develops micro-burrs. The earplugs come out with sharp edges that the user can feel. Real factories pull and refurbish moulds at scheduled intervals; brokered production runs whatever's already on the press.
Step 3: De-flashing and inspection
Out of the mould, each earplug has a thin "flash" line where the mould halves meet. Skilled operators trim the flash with curved scissors and inspect for:
- Surface bubbles (entrapped air during moulding)
- Color variation (incomplete pigment mixing)
- Hardness consistency (Shore A spot-test every 100 pieces)
- Dimensional check (calipers on every 50th piece)
Rejected plugs go to regrind for non-product applications — never back into product silicone.
Step 4: Sterilization and packaging
For our medical-grade SKUs (SA-3001, SA-3101), the plugs go through a UV sterilization tunnel before packaging. Foam-tipped plugs use ethylene oxide (ETO) gas sterilization instead, with a 14-day off-gas period before packaging.
Packaging happens in a Class 100,000 cleanroom for our hospitality and DTC SKUs — the same air-quality grade used for cosmetics packaging. This isn't legally required for hearing protection, but it matters for the touch-and-smell experience your customer has when they open the package.
Step 5: Final QC and outbound
Every shipment is sampled at 2.5 AQL (Acceptable Quality Limit) — the industry standard for textile and plastic PPE per the ISO 2859-1 sampling plan. That means for a 10,000-pair shipment, ~125 pairs get pulled and inspected for visual defects, hardness consistency, and packaging integrity. If more than 4 fail, the entire shipment gets re-inspected.
The buyer receives a digital Certificate of Inspection before the container leaves Shanghai port.
What this means for your tech pack
When you brief a factory on a new earplug SKU, the things that drive cost are (in order):
- Material grade: FDA food-contact silicone vs general-purpose silicone is ~20% cost difference.
- Mould cost: existing mould = $0 tooling; custom shape = $3-8K amortized.
- Cleanroom packaging: ~5-8% premium, but visibly increases retail conversion.
- Sterilization method: UV (silicone) is cheap; ETO (foam) requires the 14-day off-gas hold.
- OEM packaging: blister vs. jar vs. retail box; printing cost driven by colors and finish.
For a transparent quote that breaks all five line-items out, talk to SIAN wholesale. We'll send a per-pair cost sheet annotated against your spec.