Quality Control for Prepainted & Laminated Steel
Five control stages. Full traceability. Documents you can review before you commit. Every order runs through a structured QC system — from incoming coil to loaded container — so what you order is what arrives.
- ISO 9001:2015 Certified
- SGS Verified
- 5 QC Stages
- 24H Complaint Response
WHY IT MATTERS
Sourcing Steel Overseas Shouldn't Be a Gamble
Color drift across panels. Coating that fails after forming. Missing paperwork at customs. These are the risks that turn a good price into an expensive problem — and they’re exactly what our QC system removes before your container ships.
Verified Before Dispatch
Every batch is checked and cleared before it leaves. No spot-checks.
Documented on Every Order
MTC and OQC report ship as standard — no extra charge.
Traceable After Delivery
Full production record for any coil, retrievable in one business day.
Every Order Passes Through Five Control Stages
From product approval to complaint closure, each stage is controlled, documented, and traceable.
NPI · New Product Introduction
Specs are signed off before first production. A trial run and First Article Inspection confirm every detail against your spec, so nothing scales until it's locked in.
IQC · Incoming Quality Control
Every base coil is checked before production — substrate thickness, zinc/AZ coating weight, tensile strength, and coating chemistry against the MTC. Material passes before it moves.
PQC · Process Quality Control
The coating line runs under continuous automated monitoring. DFT and color difference (ΔE) are measured every meter, with SPC charts on key parameters — so drift gets caught in the run, not after it.
OQC · Outgoing Quality Control
Before release, each batch faces final inspection: T-Bend, pencil hardness, MEK rub, cross-cut adhesion, gloss, and packaging integrity. No coil ships without an MTC.
CS · Customer Complaint Handling
Every complaint follows structured 8D methodology. We acknowledge within 4 business hours and close root cause plus corrective action within 5 days — fixed at the source, not patched.
The Documents That Arrive With Your Order
Procurement teams ask one question more than any other: what paperwork comes with the goods? Here's the standard set — every item issued per production batch, not per container.
Mill Test Certificate (MTC)
Chemical composition, zinc/AZ coating weight, tensile strength, yield point, and elongation — linked to the coil batch number and traceable to the steel mill.
OQC Inspection Report
T-Bend, pencil hardness, MEK rub, cross-cut adhesion, DFT, gloss, and visual sign-off. Issued by our QC team before loading.
Packing List & Coil Labels
Each coil labeled with grade, coating system, thickness, width, batch number, and production date. The packing list matches your shipping documents exactly.
SGS Third-Party Test Report
Independent SGS verification of salt spray, adhesion, T-Bend, and MEK rub. Accepted by most international specifiers and building authorities.
RoHS & REACH Declaration
Confirms no restricted substances under EU RoHS (2011/65/EU) and REACH (EC 1907/2006). SVHC declarations available.
Color Approval Sample
A physical color chip from your actual production run, verified by spectrophotometer to ΔE ≤ 1.0 against your reference. Sent before bulk shipment.
Independent inspection welcome. We accept pre-shipment inspection by SGS, Bureau Veritas, TÜV, or any agency you nominate. Book it at least 7 days out — we hold the cargo, cooperate fully, and help schedule on-site access at no extra charge.
Test Methods & Acceptance Criteria
All OQC tests reference EN 10169 and GB/T 12754, with SGS-verified results available per batch. Below are the standard acceptance criteria for export PPGI/PPGL coil.
| Test Item | Test Method | Acceptance Criteria | Applies To |
|---|---|---|---|
| Dry Film Thickness (DFT) | EN ISO 2808 / ASTM D7091 | Top coat ± 2 μm of specified value | All coating systems |
| Color Difference (ΔE) | CIE Lab, D65 illuminant | ΔE ≤ 1.0 vs. approved color chip | All coating systems |
| Gloss Level | EN ISO 2813 (60°) | Within ± 5 GU of specified value | All coating systems |
| T-Bend Adhesion | EN ISO 1519 / ASTM D4145 | No cracking: 0T–1T (PE); 1T–2T (SMP/HDP); 1T–3T (PVDF) | All coating systems |
| Cross-Cut Adhesion | EN ISO 2409 | Grade 0 or Grade 1 | All coating systems |
| Pencil Hardness | ASTM D3363 | H to 2H (no film removal) | All coating systems |
| MEK Rub Resistance | ASTM D5402 | ≥ 100 double rubs (no film removal) | All coating systems |
| Salt Spray Resistance | EN ISO 9227 (NSS) | PE: 300–500h; SMP: 500–1,000h; HDP: 750–1,000h; PVDF: 1,000–1,500h+ | Per coating system |
| Zinc Coating Weight | EN ISO 1460 / GB/T 1839 | Within ± 5% of specified Z or AZ value | GI and GL substrates |
| Steel Thickness | EN 10131 / EN 10143 | Within standard thickness tolerance | All substrates |
Traceable From Coil to Customer
Every coil gets a unique batch number at production, linking all five records below. If an issue appears after delivery, we retrieve the complete production record for any coil within one business day.
Raw Material MTC
Base steel grade, zinc/AZ coating weight, and heat number from the upstream mill.
Coating Line Records
Oven temperature profile, line speed, DFT readings, and primer/topcoat batch numbers.
Operator & Equipment Log
Shift, equipment ID, and calibration status at the time of production.
OQC Test Results
All test data linked to the batch number, retained 5 years minimum.
Shipping Record
Bill of lading, container number, and port of loading linked to the batch.
Nothing Changes Without Documented Approval
Any change to spec, raw material source, or process requires a documented ECN before it goes live. Affected customers are notified before production begins.
Trigger
A change request is raised by a customer requirement, internal improvement, or regulatory update.
Impact Review
QC, technical, and sales evaluate the effect on coating performance, cost, and existing orders.
Validation Run
A trial batch is tested to the full OQC standard. Results must meet or exceed the original spec.
Sign-Off
Quality Manager and Technical Director approve. Affected customers are notified.
Release
Updated control plan and SOPs are distributed, and the change takes effect from the agreed date.
How We Handle Issues — With Proof
No process is perfect. What matters is how fast and how systematically issues get resolved. Here are two real cases from our complaint records.
Inconsistent Color Across Panels
A customer saw visible color variation between panels from the same order, installed side by side on a roof.
ΔE drift within one production run, caused by uneven oven temperature — edge sensors had fallen outside calibration tolerance.
All oven sensors recalibrated. In-line ΔE checks tightened from every 50m to every 10m. Coils outside ΔE ≤ 1.0 are now auto-flagged and quarantined before OQC.
Zero repeat complaints for this failure mode in the 18 months since. ΔE control is now standard in every PQC checklist.
Back Coat Delamination After Forming
A garage door maker reported the back coat separating from the PU foam core in about 2% of panels after roll-forming.
The customer ordered standard PPGI without stating a sandwich-panel end use. The back coat supplied was general-purpose polyester, not the high-adhesion epoxy needed for PU bonding.
The order form now requires an "end use" field. Sandwich panel orders trigger an automatic back-coat spec check before confirmation.
No delamination complaints since. The customer now specifies "PU sandwich panel grade back coat" on repeat orders, and the case is used in sales training.
Audit-Ready Compliance Documentation
Every certificate and third-party report is ready for submission to specifiers, architects, and building authorities.
ISO 9001:2015 · Quality Management System
Covers the full chain from incoming coil to finished PPGI/PPGL dispatch — pre-treatment, coating, slitting, and packing. Surveillance audit conducted annually.
- Issued by TÜV SÜD — available on request
- Scope covers prepainted and laminated steel coil production
- Internal audits conducted quarterly
SGS Third-Party Testing
Independent mechanical and chemical testing on production batches — salt spray, T-Bend, DFT, color, adhesion, and MEK rub. Issued per batch, not per shipment.
- Available per production batch on request
- Accepted by EU, US, Middle East, and Australian specifiers
- Reports reference EN 10169 and ASTM methods
Common Questions
Common Questions About Our QC Process
What AQL standard and inspection level do you use?
We follow ANSI/ASQ Z1.4 (equivalent to ISO 2859-1). Standard production runs at Level II, AQL 1.0 for general attributes. For new suppliers or critical specs — PVDF or coastal-grade coil, for example — we apply Level II, AQL 0.65 with tightened inspection until three consecutive lots pass. Switching follows standard ANSI/ASQ rules.
Can I request an independent inspection before shipment?
Yes. We accept SGS, Bureau Veritas, TÜV, Intertek, or any agency you nominate. Give us 7 days’ notice before the shipment date so we can schedule access. We provide all documentation, hold the cargo, and don’t load until the inspector releases the lot. The agency cost is on your side.
What documents come standard with every shipment?
An MTC per coil batch, an OQC inspection report, a packing list, coil labels with batch number and production date, a bill of lading, and a certificate of origin. SGS reports, RoHS/REACH declarations, and color approval samples are available on request with advance notice.
How do you keep color consistent across a large order?
For batch-critical orders, we schedule the full quantity in one continuous run. Color is measured continuously by automated spectrophotometry against your approved chip, targeting ΔE ≤ 1.0. If a run must be split, the first-run chip becomes the reference master. A production-run sample can be sent for approval before bulk shipment.
How fast do you respond to complaints?
We acknowledge within 4 business hours and give a preliminary root cause within 24 hours. A full 8D report — root cause, containment, corrective action, and recurrence prevention — follows within 5 business days, or 3 for critical, shipment-blocking issues. Every complaint is logged, tracked, and reviewed monthly.
How long do you retain quality records?
Production records and MTC: 10 years. OQC and IQC records: 5 years. Complaint and 8D records: 3 years. All records are retrievable within one business day, and we can issue certified copies on written request.
Which standards do your tests reference?
EN 10169 and GB/T 12754 are our primary references, with individual test methods drawn from EN ISO and ASTM standards. Full methods and acceptance criteria for each test appear in the Test Methods table above, and SGS-verified results are available per batch.
Get the QC Pack for Your Next Order
Tell us your product spec and application. We’ll confirm which documents are standard and which need advance notice — and reply within one business day.
- MTC and OQC report with every shipment — no extra charge
- Independent pre-shipment inspection fully supported
- All records retained and retrievable for audit
- SGS third-party reports available per batch on request
- 8D complaint closure within 5 business days
Jessica — Export Manager