Quality Control

AQL Inspection Specs for Custom Pins, Coins and Keychains

Why “Looks Good in Photos” Is Not an Inspection Standard

Most failed shipments of custom metal promotional products are not total disasters. The usual problem is a mixed lot: 80 to 90 percent acceptable pieces, 5 to 10 percent cosmetic defects, and 1 to 5 percent defects serious enough to cause retailer returns, event complaints or repacking costs. If the purchase order only says “good quality,” “same as sample” or “factory standard,” there is no objective basis for deciding whether the order should pass, be sorted, be reworked or be remade.

For enamel pins, challenge coins, keychains, fridge magnets, brooches and similar small metal giveaways, inspection criteria should be agreed before mass production starts. The inspection sheet should define the sampling standard, AQL limits, defect classes, dimensional tolerances, plating and color checks, functional tests, packing checks and the commercial response if the lot fails.

At ZheCraft, we align in-line QC and final pre-shipment checks to the buyer’s AQL sheet before export packing. That is important because many defects are cheap to correct at the workbench but expensive after shipment: weak split rings, loose clutch backs, plating burn marks, wrong Pantone enamel, misaligned epoxy domes, under-filled enamel, wrong backing cards and mixed SKU cartons.

Set Sampling, AQL and Commercial Risk Early

Most finished-goods inspections use ANSI/ASQ Z1.4 or ISO 2859-1 sampling logic. For small promotional metal products, General Inspection Level II is the normal default because it gives a practical sample size without requiring 100 percent inspection. Level III is stricter and increases sample quantity, which is useful for retail programs, paid collector merchandise, child-use items, mixed-SKU campaigns or orders with no time for replacement.

AQL is not a promised defect percentage. It is a statistical acceptance rule for the inspected sample. For example, under a common Level II plan, a 10,000-piece lot may require 200 inspected pieces. At AQL 2.5 for major defects, the lot may still pass with several major findings in the sample. It does not mean the factory guarantees exactly 2.5 percent defects in the shipment.

A balanced starting point for custom pins, coins and keychains is Critical 0, Major 2.5 and Minor 4.0. Tighten to Major 1.5 and Minor 2.5 for retail, licensed brands, safety-sensitive brooches, magnets, children’s items or urgent event orders. Avoid writing “AQL 0 for all defects” unless the budget includes 100 percent inspection, higher scrap and longer production time.

Lot quantity	Typical Level II sample	Suggested AQL	Typical FOB range	Normal China lead time
300-499 pcs	50 pcs	Critical 0, Major 2.5, Minor 4.0	US$0.65-1.80 for pins/keychains	12-18 days after sample approval
500-999 pcs	80 pcs	Critical 0, Major 2.5, Minor 4.0	US$0.45-1.35 for soft enamel pins	14-20 days
1,000-2,999 pcs	80-125 pcs	Critical 0, Major 2.5, Minor 4.0	US$0.30-1.10 depending on size and finish	18-25 days
3,000-9,999 pcs	125-200 pcs	Critical 0, Major 2.5, Minor 4.0	US$0.22-0.85 for common 25-50 mm items	22-30 days
10,000-50,000 pcs	200-500 pcs	Critical 0, Major 1.5, Minor 2.5	US$0.16-0.65 for repeat tooling orders	28-40 days

MOQ also affects inspection economics. Many factories accept 100 to 300 pieces for trial orders, but 500 pieces is a more realistic MOQ for stable unit pricing, color setup and plating line control. For multiple colorways under one design, confirm whether the MOQ applies per design, per plating finish or per enamel colorway.

Define Critical, Major and Minor Defects Clearly

Defect classes must be written in product language that an inspector can apply while holding the item. “Bad finish” is vague. “Exposed base metal larger than 0.5 mm on the front visible surface” is inspectable. The same approach should be used for enamel fill, plating, soldering, printing, magnet adhesion, barcode readability and carton assortment.

A critical defect creates safety risk, legal risk or total product failure. Examples include sharp burrs above 0.2 mm on a wearable edge, detachable small magnets, broken pin posts that can puncture skin, incorrect safety warning labels, lead or cadmium above the agreed regulatory limit, or nickel-containing plating when nickel-free plating was specified for skin contact. Critical defects should be AQL 0: one confirmed critical defect fails the lot.

A major defect affects function, saleability or brand acceptance. Examples include wrong plating finish, missing logo detail, bent pin post, clutch back not locking, split ring opening under light pull, cracked epoxy, wrong Pantone enamel beyond the approved tolerance, unreadable QR code, missing backstamp, wrong attachment, wrong backing card or front-side scratch longer than 3 mm. Minor defects are small cosmetic issues that do not affect normal use, such as a tiny polishing dot under 0.3 mm on a non-logo back area.

Defect class	Concrete examples	Recommended limit
Critical	Sharp burr above 0.2 mm, loose magnet, toxic material mismatch, broken wearable point	AQL 0
Major	Wrong color or plating, bent post, weak clutch, missing logo, plating peel, unreadable QR code	AQL 1.5-2.5
Minor	Small back rub, tiny dust speck in enamel, slight shade variation within approved range	AQL 4.0
Observation	Non-repeated issue outside the checklist but useful for next order improvement	Record only unless repeated

Use Measurable Tolerances, Not Visual Guesswork

Inspection should not rely only on judgment. The PO should list tools and tolerances: digital calipers with 0.01 mm resolution, coating thickness gauge, Pantone book or spectrophotometer, pull-force gauge, 3M 600 or equivalent tape for adhesion checks, barcode scanner and go/no-go fixtures where fit matters.

For metal items up to 50 mm, practical finished-size tolerance is usually ±0.20 mm for stamped brass, iron or stainless steel and ±0.30 mm for zinc alloy casting. Thickness tolerance is commonly ±0.20 mm for 1.2 to 2.0 mm pins and ±0.30 mm for 3.0 to 4.0 mm challenge coins. If the product fits a retail tray, acrylic box, backing-card slot or magnetic display, specify the tighter tolerance before tooling, not after first production.

Plating thickness should be specified in microns. Standard decorative nickel, gold, rose gold, antique brass, copper or black nickel plating is often 3 to 5 microns for promotional use. Premium or frequent-handling orders should use 5 to 8 microns, and outdoor or high-humidity use should add a salt-spray target such as 24 hours minimum for basic decorative resistance or 48 hours for higher durability, depending on base metal and finish.

• Finished size: ±0.20 mm for stamped metal under 50 mm; ±0.30 mm for zinc alloy castings.
• Thickness: ±0.20 mm for most pins; ±0.30 mm for 3.0-4.0 mm coins and heavy keychains.
• Pin post position: ±0.50 mm from approved artwork; tighter if the card hole or anti-rotation layout requires it.
• Enamel fill: no overflow on front logo lines; underfill not lower than adjacent metal by more than 0.20 mm unless approved.
• Epoxy dome: no bubbles over 0.30 mm on logo areas; no bare edge wider than 0.30 mm.
• Plating: 3-5 microns for standard use; 5-8 microns for premium handling or higher abrasion risk.
• Color: approved production sample controls; if using instruments, agree Delta E before production, commonly under 2.0 for strict brand colors.

Add Functional Tests for Attachments and Wear Points

A pin can look acceptable and still fail if the post bends, the clutch slips or the magnet detaches. Functional tests should be included in the AQL plan, and destructive tests should be identified separately because pull tests, bend tests and adhesion tests may damage samples. The inspection sheet should state how many pieces are sacrificed and whether they are counted inside the AQL sample.

For enamel pins and brooches, test the clutch, rubber cap, safety clasp or brooch bar under normal handling. A practical pull-force target for standard pin posts is 2.0 to 3.0 kgf, depending on post diameter, solder area and base metal. Brooch bars should complete at least 20 open-close cycles without hinge looseness or catch failure. If the pin is heavy or larger than 40 mm, consider two posts or a wider solder base.

For keychains, the failure point is often the connector rather than the logo plate. Common promotional split rings are 25 to 30 mm outside diameter with 1.6 to 2.0 mm wire. For heavier zinc alloy keychains, specify ring closure gap under 0.30 mm and a connector pull test of 3 to 5 kgf. For premium retail keychains or bottle opener keychains, increase the connector specification and inspect the jump ring after torque or pull testing.

Product	Functional check	Practical test level
Enamel pin	Post bend and clutch retention	2.0-3.0 kgf pull on selected samples
Brooch	Hinge, catch and bar strength	20 open-close cycles with no looseness
Keychain	Split ring, jump ring and chain opening	3-5 kgf pull depending on item weight
Fridge magnet	Magnet adhesion and holding power	No hand detachment; holds stated paper load on painted steel
Challenge coin	Edge burr, relief and plating rub	No burr above 0.2 mm; high points pass rub check

Control Visual Conditions and Color Approval

Many disputes start because the buyer reviews defects under a desk lamp at 10 cm while the factory inspected at arm’s length under room lighting. Define the inspection condition. A practical standard is 40 to 50 cm viewing distance, 600 to 800 lux white light, normal or corrected vision, and no magnification unless checking QR codes, micro text, suspected safety defects or plated-surface contamination.

Front surfaces should be judged more strictly than backs because they carry the logo and retail value. A 2 mm scratch across a front enamel field is usually major. The same mark on the back, away from the backstamp and attachment, may be minor. Back-side tooling marks, light rubs or polishing waves can be acceptable if they do not affect function, corrosion resistance or brand identification.

Color approval must be physical. Screen artwork is not a production standard. Use signed pre-production samples, Pantone references and material-specific expectations. The same Pantone number will not look identical in soft enamel, hard enamel, PVC, printed paper, polyester lanyard fabric and plated metal. If brand color is strict, define the method: visual match to the approved sample under D65-style light, or a measured Delta E target with the instrument and surface preparation agreed in advance.

Tie AQL to Packing, Cartons and SKU Control

A product can pass visual inspection and still fail receiving if the packing is wrong. The final inspection should cover unit packing, polybag sealing, backing cards, barcode labels, carton marks, carton weight, inner box counts and assortment ratios. For small metal items, over-heavy cartons increase the risk of crushed retail boxes, torn export cartons and mixed inventory during unloading.

A practical carton limit for pins, coins and keychains is 12 to 18 kg gross weight unless the buyer specifies otherwise. Use inner boxes, dividers or individual polybags when plated surfaces can rub. For epoxy domed products, avoid tight bulk packing immediately after doming; epoxy that is not fully cured can dent or show pressure marks after transit.

For multi-SKU programs, inspect at carton level, not only piece level. A 10-design campaign with 1,000 pieces per design should verify design count, backing card match, barcode match and carton label. A 1 percent cosmetic defect rate may be manageable; a 5 percent SKU mix-up can stop distribution because warehouse teams cannot confidently allocate stock.

• Confirm unit packing: bulk, individual polybag, backing card, velvet pouch, acrylic box or gift box.
• Check carton labels for SKU, PO number, quantity, gross weight, net weight and country-of-origin marking if required.
• Verify inner box quantities against the packing list instead of relying only on master carton totals.
• Use double-wall cartons for heavy coins or cartons above roughly 15 kg gross weight.
• Separate mirror-polished, antique, black nickel and epoxy items if rubbing or pressure marks are known risks.
• Photograph one sealed carton, one open carton and one complete inner packing layout for the shipment record.

Write the Failure Response Before Shipment

The inspection sheet should state the reaction plan before a failure occurs. If the lot fails for critical defects, shipment should stop and root cause review is required. If the lot fails for major defects, the practical options are 100 percent sorting, rework, replacement production or buyer concession with a documented discount. The right choice depends on deadline, defect type and whether the defect can be reliably separated.

Sorting works when defects are visible and binary: wrong clutch, missing backing card, mixed barcode, open jump ring or plating stain. Sorting is weak when the defect is borderline or distributed across the lot, such as slight color drift, shallow relief, low plating thickness or marginal magnet strength. In those cases, rework or remake is usually cleaner than arguing piece by piece.

Commercial responsibility should also be clear. If production does not match the approved sample, artwork or written spec, the factory should normally absorb sorting, rework or replacement cost. If the buyer changes acceptance criteria after production, approves a high-risk design against factory advice, or compresses curing and packing time to meet an event date, cost sharing may be more realistic.

Failure type	Best response	Avoid this response when
Wrong attachment or packing	100 percent sorting and repacking	Deadline does not allow manual verification
Plating peel or corrosion	Reject, replate if feasible or remake affected lot	Issue is only removable polishing compound
Color outside tolerance	Sort if batches are clearly separable	Every piece varies within normal process limits
Weak glued magnet	Rework with stronger adhesive and full cure time	Magnet pocket is too shallow for secure bonding
Sharp burrs	Deburr and reinspect 100 percent	Deburring damages plating or changes product shape

Before your next custom pin, coin, keychain or magnet order reaches mass production, attach a one-page AQL sheet to the PO. Include the sampling standard, inspection level, AQL limits, defect classes, tolerances, functional tests, packing checks and failure response. Attach approved artwork, the signed golden sample, packaging dielines, barcode rules and carton mark requirements. ZheCraft can align in-line QC, final inspection photos and pre-shipment sampling to the same document so the buyer, factory and third-party inspector judge the shipment by one written standard.

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