Tensile testing of board used in self-assembly and ready-made furniture

Requirement

Lithuania's Klaipedos Mediena and Klaipedos Baldai are part of the VMG and SBA Groups and are leading manufacturers of wooden furniture in Lithuania. Specialising in finished particle board (FPB), impregnation, lamination and veneers they produce primarily for Swedish retail giant IKEA delivering, amongst other items, over 5 million kitchen cabinets a year.

Particle board is a waste-wood product made by heat pressing wood chips, shavings or sawdust and resin together to form structural sheets for a variety of uses in ready-made furniture. Compression is applied multiple times to the particle board sheet to create the tightest possible bond between the resin and the wood fragments. As significant components in load-bearing kitchen and household furniture, it was important for Klaipedos Mediena and Klaipedos Baldai to test the physical strength of their particle board to ensure they meet the rigorous performance standards required.

Solution

Tensile test for surface soundness (EN 311)

The European Norm EN 311 stipulates the method for determining the bond strength between the particles or fibres of a board and the layer below. It requires a steel mushroom-shaped pad to be bonded to the outer surface over a defined area. The specimen is held in a steel gimbal and pulled apart until the outer layer fractures. The peak tensile force is recorded and compared to the quality specifications to make sure there are no defects in bonding.

Tensile strength test perpendicular to the surfaces (EN 319)

To measure the overall strength of the particleboard (and fibreboard) the test standard EN 319 calls for test blocks to be glued to each side of the specimen. The test blocks are then held in self-aligning grips before being pulled apart at a constant speed to ensure maximum precision. The peak tensile force is recorded by the software and compared to the quality specifications to make sure the internal bonded fibres and particles can resist the tensile loads during their use as furniture components.

Tensile strength for fastener holding tests (IKEA TM-0057, ASTM D1037)

As self-assembly furniture requires the use of many different fasteners (screws, dowels, etc.) it is essential that the particle- and fibreboard can securely hold the fasteners.

Screws are inserted to a known depth into the surface and edge of the board. The board is secured in a lower fixture and the head of the screw is held in an upper slotted fixture. In this screw retention test, a progressive load is applied at a constant speed until the screw detaches or a target load is reached. To cope with testing the board in ‘surface’ and ‘edge’ orientations a universal fixture was supplied featuring T-slots for rapid positioning of the specimen. The peak tensile force is recorded by the software and compared to the quality specifications to verify the board is fit for purpose.

Mecmesin’s MultiTest 25-xt tensile tester was the ideal choice as a versatile bench-top model capable of performing the full range of tensile tests. The Emperor software of the touchscreen-controlled test frame automatically calculated the various strength parameters for inclusion in the test report. The OmniTest (and OmniTest Touch) with VectorPro software is our latest system to provide this solution.

Furniture suppliers wishing to test to a greater range of standards also consider the following methods:

• EN 310 Bend test of particle board
• IKEA test - Peel strength of melamine veneer from particle board

Test equipment

• MultiTest-xt (or OmniTest) software-controlled, motor-driven test stand
• Appropriately rated loadcells
• Surface Soundness Jig (EN 311) - PSV17138
• Tensile Strength Jig (EN 319) - PSV17139
• Tensile Strength Jig (IKEA TM-0057) - PSV19044