1. 100% PINE FILM FACED PLYWOOD (All Fresh Pine Veneer Core)
Production Process:
- Log Selection & Peeling: Selection of straight-grained pine logs. Conditioning in hot water baths. Rotary peeling into continuous veneer sheets of specified thickness (e.g., 1.5mm, 2.0mm).
- Veneer Drying & Grading: Drying in jet dryers to target moisture content (6-10%). Automatic grading based on core/facial quality. Clipping to required dimensions.
- Glue Application & Lay-up: Application of phenolic resin (PF) glue to veneers via roller or curtain coater. Assembly of lay-up with tight, knot-free veneers on faces. Strict control of glue spread (e.g., 160-220gsm single line).
- Pre-pressing & Cold Pressing: Initial pre-pressing to consolidate the mat. Followed by cold pressing for preliminary bond formation.
- Hot Pressing: High-pressure hot pressing at specified temperature (140-155°C), pressure (18-22kg/cm²), and time (calculated by thickness). This cures the PF resin.
- Trimming & Sanding: Trimming to nominal size. Light sanding on non-film faces for uniformity (if required). Film faces are not sanded.
- Film Applying (Overlay): Application of phenolic-impregnated film (brown/black) to one or both faces using a hot-press laminating process.
- Conditioning & Final Processing: Panel conditioning to equalize moisture. Final trimming, edge sealing (if specified), grading, and branding.
Quality Control Checklist:
| Category | Inspection Item | Standard / Method | Common Defects & Imperfections |
|---|---|---|---|
| A. Appearance & Dimensional | Film Surface | Visual, EN 315 / JIS K 6925 | Scratches, impurities (black spots), resin bleed-through, film delamination, light spots (under-impregnation). |
| Core Composition | Visual on trimmed edge | Mix of wood species, oversized core gaps (>3mm width), overlapped veneers. | |
| Thickness & Tolerance | Caliper, multiple points | Out of tolerance (e.g., ±0.2mm for 12mm). | |
| Squareness & Dimensions | Tape measure, steel square | Out of spec length/width, diagonal deviation. | |
| Edge Filling & Sealing | Visual | Poor or missing edge sealant, unfilled edge voids. | |
| B. Internal Properties | Moisture Content (MC) | Moisture meter / oven dry | High MC (>12%) leads to springback; low MC (<8%) causes brittleness. |
| Bonding Quality | Boil Test (EN 314-1, Class 3) | Delamination after boiling cycle. Primary defect. | |
| Core Integrity | Visual on cut section | Excessive gaps, large sound knots, decay in core veneers. | |
| C. Laboratory Performance | Bending Strength & MOE | EN 310 | Values below standard for structural use. |
| Formaldehyde Emission | Perforator / Gas Analysis (EN 16516) | E1 (≤0.124 mg/m³) or E0 compliance. | |
| Slip Resistance | Pendulum test (EN 13893) | Critical for floor formwork. | |
| Density | EN 323 | Typically 550-650 kg/m³ for pine. |
2. RECYCLED FULL PINE JOINT CORE FILM FACED PLYWOOD (2nd Gen, Recycled Joint Core)
Production Process:
- Raw Material Preparation: Sourcing and sorting of used pine plywood/cuttings, pine pallet blocks, and pine timber offcuts. Removal of metals, debris, and degraded wood.
- Shredding & Flaking: Processing feedstock through chippers and flakers to produce engineered wood strands/flakes.
- Drying & Glue Blending: Drying flakes to target MC. Blending with waterproof PF or Methylene Diphenyl Diisocyanate (MDI) resin in a rotary blender.
- Mat Forming & Pre-pressing: Forming a uniform mat with oriented or random flake layers on a forming line. Initial cold pre-pressing.
- Hot Pressing (Core Panel): High-temperature, high-pressure pressing to form a solid, homogenous Joint Core slab.
- Core Panel Conditioning & Sizing: Stabilization, then precision sanding and cutting to consistent thickness sheets.
- Face Veneer Lamination: Key Difference: Lamination of fresh pine cross-bands (2 layers, perpendicular) and fresh pine face veneers onto both sides of the joint core using PF resin and hot pressing. This provides a stable, smooth surface.
- Film Applying (Overlay): Application of phenolic film as per the standard process.
- Final Processing: Conditioning, trimming, grading, branding.
Quality Control Checklist:
| Category | Inspection Item | Standard / Method | Common Defects & Imperfections |
|---|---|---|---|
| A. Appearance & Dimensional | Film Surface | Visual | Same as above, plus “telegraphing” – imprint of underlying joint core flakes showing through film. |
| Edge Structure | Visual on trimmed edge | Visible joint core with overlaid cross-bands. Check for core integrity, excessive voids, or glue starvation at joints. | |
| Thickness & Density | Caliper & Weight | High density variation indicates inconsistent mat formation. Must be uniform. | |
| Squareness & Dimensions | As above | As above. | |
| B. Internal Properties | Moisture Content (MC) | Moisture meter | Critical for joint core stability. Target 6-10%. |
| Bonding Quality | Boil Test (EN 314-1, Class 3) | Delamination at three key interfaces: 1) Film-to-face veneer, 2) Face veneer-to-cross-band, 3) Cross-band-to-joint core. | |
| Core Integrity & Screw Holding | EN 320 | Internal bond strength of joint core; poor bonding leads to core failure under load. | |
| Edge Soundness | Visual & manual check | Crumbling edges, poor edge screw holding indicate weak core or insufficient resin in joint core. | |
| C. Laboratory Performance | Bending Strength & MOE | EN 310 | Critical Test. MOE may be lower than 100% veneer core. Must meet declared specification (e.g., EN 636-1 S). |
| Formaldehyde Emission | As above | Typically very low (E0/E0.5) if MDI resin is used in core. Must be verified. | |
| Water Resistance & Thickness Swell | 24h immersion test (EN 317) | Joint core is susceptible to thickness swell if resin content is inadequate. | |
| Repeated Use Performance | Customer site trials | Surface wear, edge deformation after multiple pours are key performance indicators. |
Key Distinction & Final Note:
The primary difference lies in the core. The 100% Pine uses layered veneer, offering predictable, grain-based strength. The Recycled Joint Core uses a reconstituted flakeboard core, offering superior utilization of recycled material but requiring stringent control over flake geometry, resin distribution, and the lamination process of the face veneers to prevent telegraphing and ensure bond integrity. The performance of the joint core type is highly dependent on the quality of the engineered core manufacturing process.
