ISO 18914:2013 pdf free
ISO 18914:2013 pdf free.Imaging materials一Photographic film and papers
In the constant load instrument, weights are added directly to a pan and the apparatus shall be designed so that the centre of gravity of the weights will be positioned directly over the stylus. These weights should range from 1 g to 210 g. The arm may be pivoted on a threaded hinge with a knurled knob, or other provision for positioning the stylus laterally, so that many parallel scribe lines can be made on the same specimen. As an alternative, the specimen holder can be provided with lateral positioning and a simple pivot used on the stylus arm.
Alternatively, the continuous load instrument (illustrated in Figure 1) can be used2). As the arm is lowered, the sliding weight is engaged by the carriage so that, when the sliding carriage with the tray is moved away from the fulcrum of the arm, the weight slides with it. This produces an increasing weight on the stylus point as the tray moves with the carriage. This weight increases from 0g to 70 g, as the carriage moves its full travel of 180 mm. To increase the range of the apparatus, additional weights of 50 g, 100 g, and 150 g can be screwed onto the threaded rod directly over the stylus.
NOTE 1 To avoid tying up the instrument, a specimen may be immersed in the appropriate solution in a separate tray and then transferred to the equipment for evaluation.
The specimen tray shall be drawn forward with the stylus riding in contact with the surface of the specimen. The tray shall be moved at a speed, such that it shall complete its travelin 1 s to 2 s. Three scratch lines, at least 30 mm long, shall be made at each load, spaced approximately 6 mm apart. (A set of four lines may be used occasionally to index the lines according to load). The load range shall be varied to suit the material under test.
NOTE 2 If processing times are short, it may be possible to make only two passes under the stylus without changing the immersion time significantly. If hot processing solutions are used, it may be necessary to warm the tray to the processing temperature before adding the processing solution in order to maintain temperatures.
If the continuous load instrument (see Figure 1) is used, the position of the stylus shall be marked on the test specimen prior to movement of the tray. The distance that the tray moves is directly proportional to the load on the stylus caused by the sliding weight.ISO 18914 pdf download.
