scope:

This part of ISO 148 covers the verification of pendulum-typeimpact testing machines, in terms of their constructional elements,their overall performance and the accuracy of the results theyproduce. It is applicable to machines with 2 mm or 8 mm strikersused for pendulum impact tests carried out, for instance, inaccordance with ISO 148-1. It can be applied to pendulum impacttesting machines of various capacities and of different design.Impact machines used for industrial, general or research laboratorytesting of metallic materials in accordance with this part of ISO148 are referred to as industrial machines. Those with morestringent requirements are referred to as reference machines.Specifications for the verification of reference machines are foundin ISO 148-3. This part of ISO 148 describes two methods ofverification. a) The direct method, which is static in nature,involves measurement of the critical parts of the machine to ensurethat it meets the requirements of this part of ISO 148. Instrumentsused for the verification and calibration are traceable to nationalor international standards. b) The indirect method, which isdynamic in nature, uses reference test pieces to verify points onthe measuring scale for absorbed energy. The requirements for thereference test pieces are found in ISO 148-3. A pendulum impacttesting machine is not in compliance with this part of ISO 148until it has been verified by both the direct and indirect methodsand meets the requirements of Clause 6 and Clause 7. This part ofISO 148 describes how to assess the different components of thetotal energy absorbed in fracturing a test piece. This totalabsorbed energy consists of ? the energy needed to fracture thetest piece itself, and ? the internal energy losses of the pendulumimpact testing machine performing the first half-cycle swing fromthe initial position. NOTE Internal energy losses are due to thefollowing: ? air resistance, friction of the bearings of therotation axis and of the indicating pointer of the pendulum whichcan be determined by the direct method (see 6.4.5); ? shock of thefoundation, vibration of the frame and pendulum for which nosuitable measuring methods and apparatus have been developed.