POLYMER TEST SAMPLES
The time spent preparing the test samples is just as important as the time spent calibrating the testing machines. Moulded Test Samples The draw angles on the side faces of a moulded test sample often prevent the test sample from sitting squarely in the notching cutter and the testing machine. Also, moulding notch profiles is problematic, especially producing the small radii in the "V" profile. Accordingly, machine a square datum face and then machine the notch profile from that face. Cut with a Cutter Press This is the most popular way of producing test samples from sheet material. However, some materials are too thick for this method. They become distorted as the cutter forces its way through the material and score marks can be left on the faces. If there is no alternative method available, first cut the sheet to approxiamatly the correct shape so that the surplus material will fall away when the cutter is used thus dramatically reducing the cutting load. Machining Test Samples CNC machines are now available dedicated to cutting polymer test samples. With spindle speeds up to 30,000 rpm and high relief angle cutters, the cutting temperature is significantly reduced as most of the heat is expelled with the swarf. The picture shows a typical set up.