Quality Assurance · PPGI / PPGL Coil
Quality Control for Pre-Painted & Laminated Steel
End-to-end assurance from incoming raw material to outgoing shipment — with full MTC traceability, SGS-verified test reports, and audit-ready documentation on every order.
ISO
9001:2015 Certified
SGS
Third-Party Verified
5
QC Control Stages
24H
Complaint Response
Quality System Flow
NPI
New Product Introduction
Design review · FAI · Control plans
IQC
Incoming Quality Control
Substrate · Zinc weight · Coating chem.
PQC
Process Quality Control
In-line DFT · ΔE · SPC monitoring
OQC
Outgoing Quality Control
T-Bend · Salt spray · Packaging check
CS
Customer Service
8D CAPA · Complaint closure ≤ 5 days
Five QC Stages
End-to-End Quality Control System
Every order passes through five structured control stages. Each stage has defined test methods, acceptance criteria, and documented outputs — available to customers on request.
Stage 01
NPI — New Product Introduction
Quality standards and specification sign-off before first production. Includes trial run and First Article Inspection against agreed customer spec.
Stage 02
IQC — Incoming Quality Control
All incoming base coils are checked before production: substrate thickness, zinc/AZ coating weight, tensile strength, and coating chemistry against MTC.
Stage 03
PQC — Process Quality Control
Continuous automated monitoring during the coating line: dry film thickness (DFT) and colour difference (ΔE) measured every meter. SPC charts maintained for key process parameters.
Stage 04
OQC — Outgoing Quality Control
Final batch inspection before release: T-Bend, pencil hardness, MEK rub, cross-cut adhesion, gloss level, and packaging integrity. MTC issued per coil batch.
Stage 05
CS — Customer Complaint Handling
Structured 8D methodology for all complaints. Initial acknowledgment within 4 business hours. Root cause analysis and corrective action report closed within 5 days.
Documentation With Every Order
What You Receive With Each Shipment
The most common question from procurement teams: what documents come with the cargo? Below is the standard set — every item is issued per production batch, not per container.
Standard · Every Shipment
Mill Test Certificate (MTC)
Chemical composition, zinc/AZ coating weight, tensile strength, yield point, and elongation — all linked to the specific coil batch number. Full traceability back to the steel mill.
Standard · Every Shipment
OQC Inspection Report
T-Bend result, pencil hardness, MEK rub test, cross-cut adhesion, DFT measurements, gloss level, and visual inspection sign-off. Issued by our QC team before loading.
Standard · Every Shipment
Packing List & Coil Labels
Each coil labelled with product grade, coating system, thickness, width, batch number, and production date. Packing list matches shipping documents exactly.
On Request · Per Batch
SGS Third-Party Test Report
Independent verification by SGS covering salt spray resistance, coating adhesion, T-Bend, and MEK rub. Accepted by most international specifiers and building authorities.
On Request
RoHS & REACH Declaration
Confirmation of no restricted substances per EU RoHS Directive (2011/65/EU) and REACH Regulation (EC 1907/2006). SVHC declarations available on request.
On Request
Colour Approval Sample
Physical colour chip from the actual production run, verified by spectrophotometer to ΔE ≤ 1.0 against customer-approved reference. Dispatched before bulk shipment.
Third-Party Inspection
We welcome third-party pre-shipment inspection by SGS, Bureau Veritas, TÜV, or any customer-nominated agency. Please arrange at least 7 days before the scheduled shipment date. Our team provides full cooperation and assists with on-site scheduling at no additional charge.
Test Methods & Acceptance Criteria
How We Test — and What We Accept
All OQC tests follow EN 10169 and GB/T 12754 as primary references. SGS-verified results are available per batch. The table below lists 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 |
| Colour Difference (ΔE) | CIE Lab, D65 illuminant | ΔE ≤ 1.0 vs. approved colour 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 |
Batch Traceability
Full Traceability From Coil to Customer
Every coil is assigned a unique batch number at production that links all of the following records. If a quality issue arises after delivery, we can retrieve the complete production record for any coil within one business day.
→
Raw material MTC — base steel grade, zinc/AZ coating weight, heat number from the upstream steel mill
→
Coating line records — oven temperature profile, line speed, DFT readings, primer and topcoat batch numbers
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Operator and equipment log — shift, equipment ID, and calibration status at time of production
→
OQC test results — all test data linked to the batch number and retained for 5 years minimum
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Shipping record — bill of lading, container number, and port of loading linked to batch
Change Control
ECN Workflow
Any change to product specification, raw material source, or production process requires a documented ECN before implementation. Customers affected by a specification change are notified before the change goes into production.
1
Trigger
Change request raised by customer requirement, internal improvement, or regulatory update.
2
Impact Review
Cross-functional team (QC, technical, sales) evaluates effect on coating performance, cost, and existing customer orders.
3
Validation Run
Trial production batch tested to full OQC standard. Results must meet or exceed original spec before approval.
4
Sign-Off
Quality Manager and Technical Director approval required. Affected customers notified.
5
Release
Updated control plan and SOPs distributed. Change implemented from agreed effective date.
8D Case Studies
How We Handle Problems When They Occur
No manufacturing process is perfect. What matters is how quickly and systematically problems are identified and resolved. These are two real examples from our complaint records.
Building Materials · Roofing Application
Inconsistent Colour Across Panels
Problem
Customer reported visible colour variation between panels from the same order when installed side by side on a roofing project.
Root Cause
ΔE drift during a single production run caused by uneven oven temperature distribution — temperature sensors at the coil edges were outside calibration tolerance.
Corrective Action
All oven temperature sensors recalibrated. In-line ΔE measurement frequency increased from every 50m to every 10m. Coils outside ΔE ≤ 1.0 now automatically flagged and quarantined before OQC.
Outcome
Zero repeat complaints for this failure mode in the 18 months following the corrective action. ΔE control is now part of the standard PQC checklist for all production runs.
Appliance Application · Sandwich Panel
Back Coat Delamination After Forming
Problem
A garage door manufacturer reported that the back coat was separating from the PU foam core in approximately 2% of panels after roll-forming.
Root Cause
Investigation found the customer had ordered standard PPGI without specifying sandwich panel end use. The back coat supplied was a general-purpose polyester, not the high-adhesion epoxy formulation required for PU bonding.
Corrective Action
Order form updated to require "end use" field for all coil orders. Sandwich panel orders now trigger automatic back coat specification check before production confirmation.
Outcome
No delamination complaints since process change. Customer now specifies "PU sandwich panel grade back coat" on all repeat orders. Case used in sales team training.
Certifications & Standards
Audit-Ready Compliance Documentation
All certification documents and third-party test reports are available for submission to specifiers, architects, and building authorities.
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ISO 9001:2015 — Quality Management System
Covers the full manufacturing chain from incoming coil to finished PPGI/PPGL dispatch. Scope includes pre-treatment, coating, slitting, and packing. Surveillance audit annually.
- Issued by TÜV SÜD — available on request
- Scope includes pre-painted and laminated steel coil production
- Internal audits conducted quarterly
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SGS Third-Party Testing
Independent mechanical and chemical testing by SGS on production batches. Reports cover salt spray, T-Bend, DFT, colour, adhesion, and MEK rub. Issued per batch, not per shipment.
- Available per production batch on customer request
- Accepted by EU, US, Middle East, and Australian specifiers
- Reports reference EN 10169 and ASTM test methods
Industry Standards Compliance
EN 10169
GB/T 12754
ASTM A755
JIS G 3312
RoHS 2011/65/EU
REACH EC 1907/2006
ANSI/ASQ Z1.4 (AQL)
EN ISO 9227 (Salt Spray)
FAQ
Common Questions About Our QC Process
What AQL standard do you use, and what inspection level?
We follow ANSI/ASQ Z1.4 (equivalent to ISO 2859-1). Standard production uses Inspection Level II, AQL 1.0 for general attributes. For new suppliers or critical specifications (e.g. PVDF or coastal-specification coil), we apply Level II, AQL 0.65 with tightened inspection until three consecutive lots pass. Switching rules follow the standard ANSI/ASQ protocol.
Can I request third-party inspection before shipment?
Yes. We accept inspection by SGS, Bureau Veritas, TÜV, Intertek, or any customer-nominated agency. Please notify us at least 7 days before the planned shipment date so we can schedule inspector access. We provide all test documentation, hold the cargo for inspection, and do not load until the inspector releases the lot. The customer bears the inspection agency cost.
What documents are included as standard with every shipment?
Every shipment includes: Mill Test Certificate (MTC) per coil batch, OQC inspection report, packing list, coil identification labels with batch number and production date, bill of lading, and certificate of origin. SGS third-party test reports, RoHS/REACH declarations, and colour approval samples are available on request with advance notice.
How do you ensure colour consistency across a large order?
For orders where batch consistency is critical, we schedule the entire quantity in one continuous production run. Colour is measured continuously during production via automated spectrophotometry against the customer-approved colour chip (ΔE ≤ 1.0 target). If a production run must be split, the first-run chip is used as the reference master for subsequent runs. A production-run colour sample can be dispatched for approval before bulk shipment.
How quickly do you respond to complaints, and what is the process?
Initial acknowledgment within 4 business hours of complaint receipt. Preliminary root cause assessment within 24 hours. Full 8D report — including root cause, containment action, corrective action, and recurrence prevention — delivered within 5 business days for standard complaints, or 3 business days for critical (shipment-blocking) issues. All complaints are logged and tracked. Recurrence rate is reviewed monthly.
How long do you retain quality records?
Production records and MTC: 10 years. OQC test reports and IQC records: 5 years. Customer complaint and 8D records: 3 years. All records are retrievable within one business day for audit or dispute purposes. We can provide certified copies of production batch records on written request.
Request Documentation
Get the QC Pack for Your Next Order
Tell us your product specification and intended application. We'll confirm which documents are available as standard and which require advance notice — and respond within one business day.
- MTC and OQC report issued with every shipment — no extra charge
- SGS third-party reports available per batch on request
- Third-party pre-shipment inspection fully supported
- 8D complaint closure within 5 business days
- All records retained and retrievable for audit
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