PET Strapping Quality Inspection Checklist

Inspection on this product is not about checking everything — it is about checking the handful of characteristics where a defect would survive installation, be invisible at the time, and fail later. Those characteristics are known, and they can be written into an inspection plan in an afternoon.

This is that plan for pet strappings.

Start from the failure modes, not from the drawing

The three defects that actually cost money on this product:

• 1. Strap losing tension on the pallet. strap stressed near its limit at tensioning; PET creeps back a few percent — tension to 50–60 % of breaking load, not 80
• 2. Weak friction welds. wrong weld time for the gauge on the tool; the joint fails at 60 % of strap strength instead of 80+
• 3. Roll deforming in heat. strap wound too tight or stored in the sun; the coil sets an oval and then feeds badly on the machine

Every inspection point below exists to catch one of those, or to catch the material and dimensional drift that produces them.

What a pet strapping must be checked against

polyethylene terephthalate (PET) embossed strap, UV-stabilised is the specified material; the accepted grades are hand grade 12.7–16 mm; machine grade 15.5–19 mm; heavy duty 19–32 mm; UV-stabilised outdoor grade; printed (customer logo) strap. The governing standard is ASTM D3950, ASTM D882, ISO 4892-3, and the dimensions covered are width 12.7–32 mm; thickness 0.6–1.3 mm; breaking loads 300–850 kg; core 200 or 406 mm.

Write those four facts at the top of the inspection plan. An inspector with no specification will measure what is easy to measure and pass the batch.

Incoming material check

1. Grade evidence: a mill certificate or a supplier declaration of grade is the minimum; on stainless, an XRF check on a sample settles it in minutes.
2. Material condition: straightness, surface defects, inclusions, delimitation or porosity visible before forming.
3. Pre-coating preparation: degreasing and pickling evidence where the finish depends on it — a coating over a contaminated surface fails as a whole.

Dimensional inspection

Against width 12.7–32 mm; thickness 0.6–1.3 mm; breaking loads 300–850 kg; core 200 or 406 mm:

1. Measure the functional dimensions, not just overall size — the dimensions that make the part fit are the ones a supplier is most tempted to run loose.
2. Check the dimensions that govern assembly: hole patterns, thread forms, radii and interface faces.
3. On a sample of 5–10 pieces, measure with the same instrument the specification nominates. Two methods give two answers.

Finish and coating

embossed both faces; green (standard), black, or printed custom colour

1. Measure coating thickness or coating mass on a sample per batch, at three points including a cut edge.
2. Look specifically at cut ends, drilled holes and bend radii — coatings fail there first.
3. Check for coating damage from handling and packing, which is a supplier process problem, not a product problem.

Mechanical and electrical tests

Your specification should name these; the inspection should confirm they were run and the records kept:

• breaking load and elongation per roll lot — confirm the certificate, the sample size and the date.
• system strength with the specified buckle/seal — confirm the certificate, the sample size and the date.
• UV ageing 1000 h (outdoor grade) — confirm the certificate, the sample size and the date.
• weld joint efficiency of friction-welded seals — confirm the certificate, the sample size and the date.
• coil wind and camber check — confirm the certificate, the sample size and the date.

Per ASTM and ISO sampling practice, an inspector normally works to an AQL of 1.0 for major defects and 2.5 for minor ones unless your order says otherwise. Agree the definition of “major” in advance — on this product, anything affecting load path or coating integrity is major.

Pre-shipment inspection checklist

1. Quantity and part numbers against the packing list.
2. Dimensional sample per the plan above.
3. Coating or finish measurements recorded with photographs.
4. Functional test on an assembled sample where the product is supplied as a set.
5. Marking and labelling correct on the product, the bag and the carton.
6. Packing verified: coils cartoned 2 per box, palletised; keep out of direct sun in the yard.
7. Test records and certificates present and matching this batch.
8. Container loading supervised, with seals recorded.

If a batch fails

Do not start with a price discussion. Start with three questions: how many pieces are affected, what is the containment, and what is the root cause. A supplier who can answer all three is a supplier you can keep. On this product the usual resolutions are a 100 % sort, a rework of the coating or finish, or a re-run — and the cost of the sort should be settled before the goods move, not after.

Related: the pet strapping specification guide is where the tolerances this inspection measures should be defined in the first place, and the supplier selection guide covers what to ask before you get to this stage.