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Adjusting & fastening

Three-Bar / Three-Position Adjuster and Needle-Through Buckle

A frame with two cross bars that gives the webbing three distinct seats, so the strap can be indexed to fixed positions instead of sliding freely. The related needle-through (zhen-tong) fitting pins the strap end through both layers so it cannot draw back. Zinc die casting allows a shaped frame, a logo on the bridge and a thicker section where the load path runs.

Overview

Made by
Qinxi in-house
Materials
Zinc alloy (Zamak 3 / Zamak 5), Brass (stamped version), Iron / steel (stamped version)
Finish options
Nickel, Nickel-free, Antique brass, Gunmetal, Black nickel, Matte black electrophoresis, Brushed
Customization
Number and spacing of positions, Logo on the bridge, Sizes for 15 / 20 / 25 / 32 / 38 mm webbing, Pin length and pin-hole diameter for needle-through versions, Plating matched to the hardware set

Applications

  • BackpacksShoulder strap and sternum strap indexing; positions are meant to be repeatable
  • Crossbody bagsStrap-end fixing and length indexing in one part
  • HandbagsUsed on webbing or thin leather straps where a visible indexed adjuster is part of the design
  • BeltsWebbing belt indexing behind the buckle
  • Denim & workwearUtility strap and tool-loop indexing on workwear

Selection tips

  • Use a three-bar adjuster where the strap is set once and must stay set; use a single-centre-bar slide where the user re-adjusts often.
  • Indexing depends on webbing thickness as much as on the metal: confirm with the production webbing, not with a sample off the shelf.
  • Avoid holding a strap permanently at the first or last position, which loads one bar continuously; rotating positions spreads wear.
  • For needle-through versions, specify pin diameter and length together with the strap build-up - a pin that is too short does not lock, too long and it snags.
  • Ferrous stamped versions can trigger needle detectors; zinc die-cast and brass versions do not.

Manufacturing process & quality control points

Qinxi in-houseSupply chain / partnersIn-house or supply chain
  1. 1

    Position layout and fit study

    Qinxi in-houseZinc & Aluminum Alloy Die Casting

    The number of positions and the bar spacing are laid out against the webbing thickness and the adjustment range the designer wants. Bar spacing that is too tight makes threading hard; too loose and the strap jumps a position under load.

    Quality control points

    • Position spacing vs webbing thickness · Prototyping and threading trial · Each new tool or project
  2. 2

    Tool build and die casting

    Qinxi in-houseZinc & Aluminum Alloy Die Casting

    Tool machined in-house and parts die cast, de-gated and tumbled. The bars are the load path, so fill at the bar roots is checked rather than only the outer frame.

    Quality control points

    • Fill and porosity at bar roots · Visual check under 600-1000 lx, 300 mm distance · First 5 pieces per cavity per shift
    • Slot width on the production webbing · Fit test with the actual webbing to be sewn · First article + every 2 hours
  3. 3

    Deburring and polishing

    Supply chain / partners

    Slot edges, bar ends and the reverse side are deburred. Sharp bar ends cut webbing over time and are a needle-breakage risk on automated lines.

    Quality control points

    • Bar end and slot burr · Gloved touch check plus 10x loupe · Per lot, AQL 2.5 (ISO 2859-1 general level II)
  4. 4

    Plating

    Supply chain / partners

    Plated to the target colour with thickness and corrosion verified against the agreed specification.

    Quality control points

    • Coating thickness · XRF coating thickness gauge (ISO 3497 / ASTM B568) · One set per plating colour per batch
    • Corrosion resistance · Neutral salt spray, 5% NaCl, 35 C (ISO 9227 / GB/T 10125) · One sample set per batch
  5. 5

    Index retention and pull test

    Supply chain / partners

    Finished parts are threaded with the production webbing, loaded, and checked for position jump, then pulled to failure. For needle-through versions the pin-hole alignment and the pin's resistance to pull-out are checked on the actual strap build-up.

    Quality control points

    • Position retention under load · Fit test with the actual webbing to be sewn · One sample set per batch
    • Pull-to-failure and failure mode · Universal tensile machine, 50 mm/min, record peak and failure mode · One sample set per batch

Relevant compliance

Get a quote for three-bar / three-position adjuster and needle-through buckle

Custom shapes, finishes and logos. Email us your artwork or sample photos.

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