Factory Direct Plastic Zipper Bottom Stop Accessories

Plastic zipper bottom stops are precision‑molded components that secure the lower end of a zipper chain, preventing slider run‑off and maintaining chain alignment during repeated opening‑closing cycles. As a factory‑direct supplier we control the entire molding process, allowing tight tolerances on critical dimensions and consistent material properties across large production runs.

Material Composition and Performance

The stops are manufactured from acetal copolymer (POM‑C) with a nominal density of 1.41 g/cm³ and a melt flow index of 8 g/10 min (230 °C/2.16 kg). This material provides a tensile strength of approximately 65 MPa, a flexural modulus of 2.8 GPa, and excellent resistance to oils, solvents, and repeated flexing. Typical operating temperature range is –40 °C to +85 °C, suitable for apparel, luggage, and industrial fastening applications.

Dimensional Specifications

Standard bottom stops are designed for zipper chain widths of 3 mm, 4 mm, and 5 mm. The stop height (measured from the chain base to the top of the stop) is typically 2.0 mm ± 0.1 mm, while the thickness across the chain is 1.2 mm ± 0.05 mm. Critical features include a molded radius of 0.3 mm at the chain entry point to reduce stress concentration and a flange width of 0.6 mm that engages the zipper teeth to prevent lateral movement. All dimensions are verified using a coordinate measuring machine (CMM) with a repeatability of ±0.02 mm.

• Chain width compatibility: 3 mm, 4 mm, 5 mm (±0.05 mm)
• Stop height: 2.0 mm ± 0.1 mm
• Flange thickness: 1.2 mm ± 0.05 mm
• Entry radius: 0.3 mm ± 0.02 mm

Mechanical Properties in Service

Under cyclic loading simulating 5000 open‑close operations at a speed of 30 mm/s, the stops retain >95 % of their original retention force, measured as the pull‑off load required to disengage the slider from the stop. The retention force for a 4 mm chain stop averages 12 N ± 1 N. Impact resistance is evaluated using a falling‑weight test (0.2 kg from 100 mm height); no cracking or deformation is observed after 10 impacts. These values are derived from internal validation tests and are representative of typical production lots.

Typical Applications and Functional Benefits

In apparel manufacturing, bottom stops prevent slider detachment on jackets, sportswear, and outdoor gear where repeated flexing occurs. For luggage and bags, the stops maintain chain integrity under dynamic loads caused by handling and vibration, reducing the likelihood of zipper failure during transport. In industrial settings such as protective covers for machinery, the chemical resistance of POM‑C ensures long‑term performance when exposed to lubricants and cleaning agents. The low friction surface of the molded stop also contributes to smooth slider travel, lowering the actuation force required by the end user.

Quality Control Philosophy

Each production lot undergoes incoming material verification via FTIR to confirm polymer composition. In‑process checks include dimensional sampling every 30 minutes using automated vision systems that flag deviations beyond ±0.05 mm. Final inspection consists of a visual check for flash, a functional test where a slider is run across 20 stops to confirm free movement, and a pull‑off test on a sample of five stops per lot. All data are logged and traceable to the specific mold cavity and shift, supporting root‑cause analysis if a non‑conformance arises.

Customization Options

Beyond standard geometries, we can adjust stop height, flange width, and entry radius to match specific chain designs or to accommodate reinforced tape thicknesses. Color customization is available through masterbatch blending, offering standard black, white, or any Pantone‑matched hue upon request. For applications requiring additional wear resistance, a PTFE‑filled POM‑C variant can be supplied, reducing the coefficient of friction from 0.20 to 0.12. Tooling modifications are quoted based on the complexity of the feature change, with typical lead times of 3‑4 weeks for new molds.

Packaging and Shipping

Stops are packed in anti‑static polyethylene bags containing 5000 units each, then placed in corrugated cartons sized 300 mm × 200 mm × 150 mm with a maximum gross weight of 12 kg per carton. Cartons are sealed with pressure‑sensitive tape and labeled with part number, lot code, and quantity. For overseas shipments, cartons are stacked on ISO‑standard pallets, stretch‑wrapped, and corner‑protected to withstand typical handling forces of up to 1.5 g. Delivery terms are ex‑works (EXW) or FOB Shanghai, with transit times dependent on destination.

Frequently Asked Questions

Technical Inquiry

To discuss your specific zipper bottom stop requirements, share your chain specifications, target quantities, and any performance criteria. Our engineering team will review the details and return a feasible solution with pricing and lead‑time information within two business days.