Operational Loads on Tables

One of the basic quality tests of the project and the implementation of the con­struction of a table is to determine its stability. The basic static scheme here is loading the table worktop with a vertical force with the value of 600 N at a distance of 50 mm from the front edge of the top and a horizontal force with the value from 300 to 400 N (Fig. 6.108a). Durability of tables is tested by loading the surface of the worktop with a weight of 50 kg and applying a horizontal load with the value from 200 to 300 N, at a distance of 50 mm from the side edges of the table top (Fig. 6.108b). Another way of loading, which checks the durability of the con­struction of the table, is applying a vertical concentrated force with the value of 400-600 N, applied at a distance of 50 mm from the side and front edge of the worktop (Fig. 6.108c).

Testing durability of tables is aimed at, among others, to confirm or exclude the ability of the construction to ensure that, at the time of using, it can endure moving with no apparent deformations of the worktop. During laboratory tests, the worktop is evenly loaded with a maximum weight of up to 100 kg, while the weights should not: protrude beyond the edges and be able to move during the test. Then, a horizontal force of 300 N should be applied at right angle to the edge of the surface of the worktop of the table, at a point 50 mm distant from the corners. This force shall be applied alternately (Fig. 6.109a).

Another type of test is checking the strength of the worktop and the frame of the table to occasional, short vertical loads. In these tests, a downward vertical force of 1000 N, pointing down, should be 10 times applied to the worktop. The acting of the force shall be maintained for 10 s ± 2 s. The test is carried out at four points shown in Fig. 6.109b or elsewhere on the worktop, where damage may occur.

An important load scheme is also a test leading to determine the stiffness indicator of the construction of tables. This indicator is included in the evaluation of vibrations

of the frames activated during use and causes unpleasant sensations to the user. These tests are conducted by applying a force of 200 N, at the height of the worktop and along its longitudinal axis, towards the centre of the table (Fig. 6.109c).