BS ISO 5893:2019 pdf download – Rubber and plastics test equipment — Tensile, flexural and compression types (constant rate of traverse) — Specification The test piece shall be held in such a manner that slip relative to the grips is prevented. When an adhesion test piece is made from different adherends, then grips of a different design might be required for each adherend. 5.4 Drive characteristics The moving crosshead of the machine shall be driven smoothly at all test speeds, and the drive shall be without any significant backlash. 5.5 Jigs for use in compression, shear and flexure testing Such jigs or fixtures shall conform with the requirements of the relevant method of test or material specification. They shall not significantly affect the accuracy of the machine by the introduction of friction, backlash or misalignment. 6 Types of force-measuring system In all cases, a continuous indication of the force applied to the test piece, preferably recorded automatically with a permanent indication of the maximum force, shall be provided. Machines with low-inertia force-measuring systems are preferred. NOTE Pendulum-type machines might have levels of friction and inertia which will significantly affect their dynamic response and decrease their accuracy. 7 Steady-state machine accuracy For each force scale, an accuracy class of 0,5, 1, 2 or 3 is specified (see Clause 4). The designation of each scale of a machine depends upon the values of relative errors of accuracy, repeatability and reversibility found when the machine is verified in accordance with ISO 7500-1. When separate scales for use in compression or other modes of operation are provided, these shall be verified separately. 8 Dynamic machine accuracy Tensile-testing machines fitted with electronic force-measuring devices may be regarded as sufficiently free of inertia at the test speeds given in Clause 10. This does not necessarily apply to the electronic recorders normally used with them, and in many cases the dynamic inaccuracy of these recorders considerably exceeds their steady-state inaccuracy. All electromechanical recorders suffer from dynamic errors which are usually made up of acceleration errors, stemming from the inertia of the device, and pen-lag errors due to mechanical and electrostatic friction effects. Measurement of dynamic recorder accuracy is best achieved by recording the error- signal level during the test. This can be done without affecting instrument performance, but it is usually technically difficult. It is therefore not considered practicable at present to specify limits and a calibration...
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