T-nuts are factory installed in the holes of the ready-to-assemble furniture components. There is a risk that the t-nut spontaneously falls out during transport or storage and get lost; the t-nut can also be pushed into inaccessible spaces during assembly. These complications can make furniture assembly impossible. For this reason, sufficient force to hold the t-nut in the hole is essential. The article presents the test results of the forces holding the t-nuts in five furniture materials (softwood, Oriented Strand Board, plywood, and particleboard in two variants). The M6 t-nuts with four prongs were installed in predrilled 8 mm holes. The resistance to withdrawal of the t-nuts was measured with a universal testing machine. The tested materials could be divided into three groups in terms of the risk of the t-nut falling out: softwood and plywood – low risk, F = 1113.2-1158.0 N; OSB and particleboard – moderate risk, F = 592.3-645.5 N, particleboard with a pad – high risk, F = 645.5 N. The results show that the withdrawal resistance is not correlated with the density of the wood material, and that it decreased with the degree of wood material processing – the less processed the material, the greater the resistance to withdrawal of the t-nuts.Unit-matice tvornički se ugrađuju u provrte dijelova namještaja spremnih za montažu. Postoji opasnost da unit-matice tijekom transporta ispadnu ili da se pri montaži umetnu u pogrešne rupe. Takve situacije mogu zakomplicirati ili onemogućiti sastavljanje namještaja. Stoga je potrebna dovoljna sila da se unit-matica zadrži u provrtu. U članku su prikazani rezultati ispitivanja sila koje drže unit-matice u pet materijala za namještaj (u drvu četinjača, OSB pločama, furnirskim pločama i u dvije varijante iverica). Unit-matice M6 s četiri trna ugrađene su u prethodno izbušene provrte od 8 mm. Otpor njihovu izvlačenju mjeren je univerzalnim uređajem za mehanička ispitivanja. Rezultati su pokazali da se prema riziku od ispadanja unit-matica ispitivani materijali mogu podijeliti u tri skupine: drvo četinjača i furnirska ploča – mali rizik, F = 1113,2 – 1158,0 N; OSB ploče i iverice – umjereni rizik, F = 592,3 – 645,5 N; iverice s podlogom – visoki rizik, F = 645,5 N. Ispitivanja su potvrdila da otpor izvlačenju nije u korelaciji s gustoćom drvnog materijala te da se on sa stupnjem prerade drvnog materijala smanjuje: što je materijal manje prerađen, to je otpor izvlačenju unit-matica veći
