Wood product inspection, wooden furniture inspection standards and methods

Wood product inspection: the key to ensuring quality and safety

The quality and safety of wood products (furniture, shelves, daily necessities, etc.) are of paramount importance. Chinese wood products are highly sought after in overseas markets, and rigorous inspection is key to ensuring they meet quality standards.

1. General inspection methods for wood products

1. Comparison basis: Strictly refer to the customer's signed sample or clear pictures and product instructions.

2. Number of inspections:

   • Orders under 50 pieces: full inspection.

   • For orders of 50 pieces or more: sampling inspection according to AQL standards.

3. Check the environment:

   • Light: 600-1000 LUX, the light source is above the examiner's head.

   • No ambient reflections.

   • The distance between the human eye and the object being measured is about 40 cm, with an angle of about 45°.

2. Core Inspection Standards and Requirements for Wooden Furniture

1. Appearance:

   • The surface is smooth, without bumps or nail punctures, and the color is uniform with no color difference (color difference between batches ≤5%).

   • No exposed bottom, peeling, bubbles, sagging, orange peel, pitting, foam marks, impurities, or bumps.

   • Smooth edges and corners, uniform thickness, and no deformation.

   • The number of concave spots (≤3mm) shall not exceed 3/10cm²; convex spots are not allowed.

2. Size/Thickness/Weight: Measured according to specifications/samples, the tolerance is generally ±3% (unless required by the customer).

3. Static load test: When the specified weight is applied to the load-bearing parts (chair seat, table top, shelf), the product should not fall over, crack, deform or lose function.

4. Stability test: Apply the specified force to pull the product in the horizontal direction, and the product should not fall over.

5. Shake test: After assembly, place it firmly and the base should not wobble.

6. Smell test: The finished product has no peculiar or irritating smell.

7. Barcode test: The label is scannable and the information is correct.

8. Impact test: A specific weight is dropped freely from a specified height onto a load surface. After the test, there are no cracks or deformations and the equipment functions normally.

9. Humidity test:

   • Measure with a moisture meter along the wood grain (contact insertion approximately 6 mm).

   • Key requirements: The moisture content of wood must be strictly controlled to prevent deformation and cracking. Generally, the moisture content of products should be ≤12%. Specific components (such as pre-stock sections and plywood) may have more detailed requirements.

10. Transport drop test (non-fragile products): Tested 10 times according to ISTA 1A standard (one point, three sides, six surfaces). No fatal or serious defects were found in the product or packaging.

3. Wooden furniture assembly inspection standards (for semi-finished products requiring customer assembly)

• in principle: Dense, flat, firm and accurate.

• Overall standards:

  1. All accessories (materials, components, hardware, instructions, etc.) must match exactly.

  2. The joints are tight and firm without cracks; the reference surface is flat; the diagonals are equal (≥1000mm error ≤1.5mm, <1000mm error ≤1.0mm); symmetrical and harmonious.

  3. Use glue correctly and in sufficient amounts (clean the parts before gluing, apply glue to the ring/side wall inside the hole, and apply glue to the tenon shoulder). Any excess glue must be wiped off in time.

• Key Metrics:

  • Warpage: For pieces with a diagonal length ≥ 700mm and < 1400mm, the warping shall be ≤ 1.5mm; for pieces with a diagonal length < 700mm, the warping shall be ≤ 1.0mm.

  • Bottom stability: ≤1.5mm (i.e. the maximum clearance when the four legs are touching the ground).

  • Perpendicularity of adjacent edges: Panel diagonal error ≥ 1000mm ≤ 1.5mm, < 1000mm error ≤ 1.0mm.

4. Hardware Inspection Standards

1. The size meets the requirements (screw length tolerance ±1mm), the nail cap is round and without cracks, the tooth level is clear, and it fits easily.

2. No rust, no scratching, no deformation, consistent size, solid structure and uniform color.

3. Works well with other accessories.

4. The appearance and shape are consistent with the sample/drawing.

5. The electroplating is firm and does not fall off.

5. Carton Inspection Standards

1. The appearance is neat and the printing is even and clear.

2. Hardness/toughness meets order requirements.

3. Nail tightly and neatly.

4. The size meets the requirements.

5. No color difference or ink pollution.

6. The mark information is accurate.

7. No scratches, wrinkles or delamination.

8. Humidity ≤12%.

6. Detailed explanation of the main defects of wood products

1. After wood processing, it is not allowed to:

   • The wood-based panel components are not edge-sealed (cross-section is exposed).

   • The covering material is debonding, bubbling, separating from the seams, and has glue penetration.

   • The joints (mortise and tenon joints, mounting plates, and supporting parts) are loose, separated, or broken.

   • The inverted ridges, round lines and rounded corners are uneven and asymmetrical.

   • The carving/wood turning pattern is asymmetrical, the bottom of the wood is uneven, and there are knife marks and cracks.

   • The outside is not polished, the inside is not finely polished, and there are saw marks.

2. After painting, it is not allowed to:

   • The whole piece/set of products has obvious color difference.

   • The paint film is wrinkled, sticky and leaking.

   • Obvious fog, white ridges, white spots, oily white, sagging, shrinkage holes, brush hairs, debris, scratches, bubbles, and peeling.

   • The surface of the covering material has depressions, pits, scratches, cracks, chipped corners and cutting edges.

   • Unpainted areas and dirty interior.

3. After hardware installation, it is not allowed to:

   • Missing parts, missing installation parts (holes exist but no parts).

   • Missing nails and nails that penetrate.

   • The moving parts are not flexible.

   • Accessories are not installed securely or are loose.

   • There are burrs around the mounting holes.