Cabinet Grade PVC Foam Board Grading Rules & Checklist
This document aligns with QB/T 5883-2023 (China cabinet/bathroom vanity board standard) and international cabinetry norms, covering grading rules and a practical inspection checklist.
Ⅰ. Grading Rules (Cabinet Grade Core Criteria)
1. Density Grade (Most Critical for Cabinets)
- Premium Cabinet Grade: 0.55–0.65 g/cm³ (Celuka/Co-extruded; high screw-holding, anti-warp, for cabinet bodies/door panels).
- Standard Cabinet Grade: 0.48–0.54 g/cm³ (general cabinet frames/shelves; meets basic hardware retention).
- Economy Cabinet Grade: 0.45–0.47 g/cm³ (only for non-structural back panels; not for load-bearing parts).
- Reject: ＜0.45 g/cm³ (insufficient strength; screw pull-out risk).
2. Thickness & Dimensional Tolerance
- Specs for Cabinets: 12mm, 15mm, 18mm (18mm for door panels; 12/15mm for carcasses).
- Tolerance: ±0.2mm (length/width: ±2mm per 2440mm sheet).
- Flatness: ≤1mm/m (no warping; critical for door alignment).
3. Surface Quality Grading (A/B/C Grades)
- Grade A (Visible Surfaces):
- No scratches, dents, or discoloration; gloss uniformity ≤5°.
- Pinholes: ≤0.5mm (≤10/m²); 0.5–1.0mm (≤5/m²); no through-holes.
- No stress whitening (bend/edge areas; no micro-cracks).
- Grade B (Hidden Surfaces):
- Minor scratches (≤0.3mm depth, ≤2cm length); slight gloss variation.
- Pinholes: 0.5–1.0mm (≤8/m²); no through-holes or large bubbles.
- Grade C (Back Panels Only):
- Allowed minor discoloration; pinholes ≤1.5mm (≤10/m²); no structural voids.
- Reject: Through-bubbles, cracks, severe discoloration, or surface collapse.
4. Mechanical Properties (QB/T 5883-2023)
表格
| Parameter | Cabinet Grade Requirement |
|---|---|
| Bending Strength | ≥18MPa (carcass); ≥15MPa (door) |
| Bending Modulus | ≥1800MPa (carcass); ≥1500MPa (door) |
| Screw Holding Strength | ≥800N (face); ≥600N (edge) |
| Impact Strength (Izod) | ≥2.5 kJ/m² (no cracking at hinges) |
5. Safety & Compliance
- Fire Retardancy: UL94 V-0 or ASTM E84 Class A (self-extinguishing).
- Heavy Metals: Pb＜100ppm, Cd＜5ppm (RoHS/REACH compliant; lead-free stabilizers).
- Moisture Resistance: Water absorption ≤0.5% (24h immersion; no swelling).
Ⅱ. Cabinet Grade Inspection Checklist (On-Site QC)
✅ 1. Visual Inspection (100% Check)
- Surface: No scratches, dents, stains, or uneven gloss.
- Color: Uniform white/coating; no streaks or patches.
- Edges: Straight, clean cuts; no chipping or crumbling.
- Pinholes/Bubbles: Grade A/B limits met; no through-holes.
- Stress Whitening: No white marks at bends/holes (no micro-cracks).
- Flatness: No warping (place on flat surface; no gaps).
✅ 2. Dimensional Check (Random Sampling: 5% per batch)
- Thickness: ±0.2mm tolerance (use digital caliper at 5 points).
- Length/Width: ±2mm per 2440mm sheet.
- Squareness: Diagonal difference ≤1mm (square corners).
✅ 3. Density & Structural Check (Random Sampling)
- Weight: 18mm sheet (1220×2440mm): 16–19kg (0.55–0.65g/cm³).
- Cut Edge: Uniform closed-cell structure; no large voids or uneven density.
- Hardness: Shore D 45–55 (press with fingernail; no deep dent).
✅ 4. Mechanical Function Test (Sample Test)
- Screw Holding: Drive 4×16mm screw; no stripping/pull-out (≥800N).
- Bend Test: 90° bend (10mm radius); no cracks or severe whitening.
- Impact Test: 500g weight drop (30cm); no dents/cracks.
✅ 5. Compliance Documentation (Mandatory)
- QB/T 5883-2023 Test Report.
- RoHS/REACH Certificate (heavy metal-free).
- Fire Retardancy Certificate (UL94 V-0).
- Density & Mechanical Property Data Sheet.
Ⅲ. Reject Criteria (Immediate Disqualification)
- Density ＜0.45 g/cm³.
- Through-bubbles or structural voids.
- Cracks, severe stress whitening, or surface collapse.
- Thickness tolerance ＞±0.3mm or flatness ＞2mm/m.
- Non-compliant heavy metals or fire retardancy failure.
Ⅳ. Application Guide by Grade
- Premium Grade (0.55–0.65g/cm³, Grade A): Kitchen/bathroom cabinet doors, visible panels, high-humidity areas.
- Standard Grade (0.48–0.54g/cm³, Grade B): Cabinet carcasses, shelves, drawer boxes.
- Economy Grade (0.45–0.47g/cm³, Grade C): Back panels, non-visible supports.
