Cosmetic caps
Essential Oil Cap (Zinc Alloy)
A zinc alloy cap for essential oil bottles, typically a small threaded closure with a reducer or dropper adapter. The shell is die cast in-house and the plastic inner liner is injection moulded in-house; plating and laser/print logo are outsourced; final assembly is done in-house.
Overview
- Made by
- Qinxi in-house
- Materials
- Zinc alloy (Zamak 3 / Zamak 5) shell, PP / PE inner liner (injection), Optional reducer / dropper adapter (sourced)
- Finish options
- High-gloss gold, Brushed gold, Matte black, PVD coating, Spray paint, UV coating
- Customization
- Bottle neck standard (18/415, 20/410, 24/410), Thread closure and reducer fit, Laser / pad-print logo, Plating and coating colour
Applications
- Essential oilsThreaded closure on an oil bottle
Selection tips
- Confirm the bottle neck standard (18/415, 20/410, 24/410) before tooling; oil bottles are standardised and the cap must match.
- Essential oils are aggressive to some platings; specify a chemical-resistant finish and verify with an immersion test.
- A reducer or dropper adapter must seat in the liner; confirm the bottle design before choosing the closure.
- EU skin-contact items need nickel-free plating to meet REACH nickel-release limits.
Manufacturing process & quality control points
- 1
Qinxi owns the 3D models and the dies for both the zinc shell and the plastic liner, so both are made in-house. Bottle neck standard and seat type are fixed at the enquiry stage.
Quality control points
- Neck standard and seat fit · Engineering review of the bottle drawing · Each new tool or project
- 2
The cap shell is die cast on Qinxi's own line, de-gated and tumbled. The neck seat and the outer face are the functional and visible surfaces, so fill and flash there are checked.
Quality control points
- Fill and porosity at the neck seat · Visual check under 600-1000 lx, 300 mm distance · First 5 pieces per cavity per shift
- Neck dimension vs bottle · Caliper and go/no-go gauge vs bottle neck · First article + every 2 hours
- 3
The PP / ABS inner liner is injection moulded on Qinxi's own line and trimmed. The liner carries the thread or seal that meets the bottle neck, so its seat dimension is the key fit check.
Quality control points
- Liner seat dimension and flash · Caliper and go/no-go gauge · First article + every 2 hours
- 4
Plating and coating
Supply chain / partnersThe shell is plated or coated to the target finish. Plating is outsourced to the supply chain; thickness, corrosion and colour are verified against the agreed specification.
Quality control points
- Coating thickness · XRF coating thickness gauge (ISO 3497 / ASTM B568) · One set per finish per batch
- Alcohol / sweat resistance (perfume contact) · Solvent wipe / immersion per agreed protocol · One sample set per batch
- 5
Laser / pad-print logo
Supply chain / partnersA logo is laser engraved or pad printed on the shell. This is done by the supply chain; logo position and legibility are checked.
Quality control points
- Logo position and legibility · 10x loupe vs master · Per lot, AQL 2.5 (ISO 2859-1 general level II)
- 6
Assembly and torque test
Qinxi in-houseThe shell, liner and any weight are assembled and the cap is screwed or pressed onto a test bottle. This final assembly is done in-house; open/close and sealing torque are checked so the cap seats squarely and does not loosen.
Quality control points
- Open/close and sealing torque · Torque gauge on a test bottle · Per lot, AQL 2.5 (ISO 2859-1 general level II)
- Liner-to-bottle seal · Fit check on the actual bottle · One sample set per batch
Relevant compliance
- EU REACH (SVHC)
EU
All metal & plastic parts, electroplated components and fabric coatings
- California Proposition 65
US
All products sold into California containing listed chemicals
- Nickel release (REACH Annex XVII Entry 27)
EU
Nickel-plated metal parts in prolonged & direct skin contact (handles, shafts, rings)
Get a quote for essential oil cap (zinc alloy)
Custom shapes, finishes and logos. Email us your artwork or sample photos.