ISO 148-2:1998 download free.Metallic materials – Charpy pendulum . impact test – Part 2: Verification of test machines.
This part of ISO 148 covers the verification of the constructional elements of pendulum-type impact testing machines. It is applicable to machines with 2 mm or with 8 mm sinkers used for pendulum impact te5ts carried out, for instance, in accordance with ISO 148-1.
It can analogously be applied to pendulum impact testing machines of other capacities and of different design.
impact machines used for industnal, general or research laboratory testing of metallic materials In accordance with this part of ISO 148 are referred to as industrial machines. Those with more stringent requirements are referred to as reference machines. Specifications for the verification of reference machines are found in ISO 148-3.
This part of ISO 148 describes two methods of verification.
a) The direct method which is static in nature and involves measurement of the critical parts of the machine to ensure that it meets the requirements of this part of ISO 148. The verification equipment shall have a certified traceability to the International Unit System. The direct method shall be used when a machine is being installed or repaired, or if the indirect method gives an incorrect result.
b) The indirect method, which is dynamic in nature, and which use reference test pieces to verify points on the measuring scale.
A pendulum impact testing machine is not in compliance with this part of ISO 148 until it has been verified by both the direct and indirect methods (see clause 12).
most recent editions of the standards indicated below. Members of lEG and ISO maintain registers of currently valid International Standards.
ISO 1481:_I), Metallic materials — Charpy pendulum impact test — Part 1: Test method.
ISO 148-3:1998, Metallic materials — Charpy pendulum impact test — Part 3: Preparation and characterization of
Charpy V reference test pieces for verification of test machines.
3 Definitions
For the purposes of this part of ISO 148, the following definitions apply.
3.1 DefinItions pertaining to the machine
3.1.1 anvil; The portion of the base of the machine forming a vertical plane which restrains the test piece when it is struck by the pendulum (see figures 1 to 3), the plane of the supports being perpendicular to the plane of the anvil.
3.1.2 base: That part of the framework of the machine located below the horizontal plane of the supports.
3.1.3 centre of percussion: That point in a body at which, on striking a blow, the percussive action is the same as if the whole mass of the body was concentrated at the point (see figure 4).
NOTE — When a simple pendulum delivers a blow along a horizontal line passing through the center of percussion, there is no resulting honzontal reaction at the axis of rotation.
3.1.4 centre of strike: That point on the striking edge of the pendulum at which, in the free hanging position of the pendulum, the vertical edge of the striker meets the upper horizontal plane of a test piece of half standard height (i.e. 5 mm) or equivalent gauge bar resting on the test piece supports (see figure 2).
3.1.5 Industrial machine: Impact machine used for industrial, general, or most research-laboratory testing of metallic materials. These machines are not used to establish reference values. Industrial machines are verified using the procedures described in this part of ISO 148.
3.1.6 reference machine: Pendulum impact testing machines used to determine the reference energy of a reference test piece. The verification requirements for this grade of machine are more stringent than those for industnal machines and are contained In Iso 148-3.
3.1.7 striker: The portion of the hammer that contacts the test piece. The edge that actually contacts the test piece may have a radius of 2 mm (the 2 mm striker) or a radius of 8 mm (the 8 mm striker). (See figure 2.)
3.2.3 indicated absorbed energy (Indicated energy), As: The energy value indicated by the pointer or other readout device.
3.2.4 nominal initial potential energy (nominal energy), AN: The energy assigned by the manufacturer of the pendulum impact testing machine.
3.2.5 reference energy, AR: The absorbed energy value associated with reference test pieces, determined from tests made using reference machines.
3.3 reference test pieces: Impact test pieces used to verify the suitability of an industrial grade, pendulum impact testing machine by comparing the indicated energy measured by that machine to the reference energy associated with the test pieces. Reference test pieces are prepared in accordance with ISO 148-3.
3.4 Definitions pertaining to test pieces (placed in the test position on the supports of the machine) (see figures 2 and 3)
3.4.1 height: Distance between the notched face and the opposite face.
3.4.2 width: Dimension perpendicular to the height that is parallel to the notch.
A pendulum impact testing machine consists of the following parts (see figures Ito 3):
a) foundation/installation;
b) machine framework — the structure supporting the pendulum, excluding the foundation;
c) pendulum including the hammer
d) anvils and supports (see figures 2 and 3);
e) indicating equipment for the absorbed energy (e.g. scale and friction pointer or electronic readout device).
6 VerifIcation
The verification of the machine can occur onty after installation and involves the inspection of the following items:
a) foundation/installation;
b) machine framework;
c) pendulum, including the hammer and the striker;
d) anvils and supports;
7.2 Inspection of the installed machine shall consist of the following.
a) Ensuring that the bolts arc torqued to the value specified by the machine manufacturer. The torque value shall be noted in the document provided by the manufacturer of the machine (see 7.1). If other mounting arrangements are used or selected by an end user, equivalency must be demonstrated.
b) Ensuring that the machine is not subject to external vibrations transmitted through the foundation at the time of the impact test.
NOTE — This can be accomplished, for example, by placing a small container of water on any convenient location on the machine framework. Absence of ripples on the water surface indicates that this requirement is met.
8 MachIne framework
Inspection of the machine framework (see figure 1) shall consist of determining the following items:
a) free position of the pendulum;
b) location of the pendulum in relation to the supports;
c transverse and radial play of the pendulum bearings;
For pendulum impact testing machines without a reference plane, the axis of rotation shall be established to be horizontal to within 4/1 000 directly or a reference plane shall be established from which the horizontality of the axis of rotation can be verified as described above.
8.3 When hanging free, the pendulum shall hang so that the striking edge is within 0,5 mm of the position where it would just touch the test specimen.
NOTE — This condition can be determined using a gauge in the form of a bar, approximately 55 mm in the length and of rectangular section, 9,5 mm in height and approximately 10 mm in width (see figure 3). The distance between the striker and the bar is then measured.
8.4 The plane of the swing of the pendulum shall be 90° ± 0,10 (3/1 000) to the axis of rotation.
8.5 The striker shall make contact over the full width of the test piece.
NOTE — One mernoci of verifying this is as follows. A test piece having dimen3ions of 55 mm x 10 mm x 10 mm is tightly wrapped in thin paper (e.g. by means of adhesive tape), and the test piece is placed in the test-piece supports. Similarly, the striker edge is tightly wrapped in carbon paper with the carbon side outermost (i.e. not facing the striker). From its position of equilibrium, the pendulum is raised a few degrees, released so that it contacts the test piece, and prevented from contacting the test piece a second time. The mark made by the carbon paper on the paper covering the test piece should extend completely across tho paper. This test may be performed concurrently with that of checking the angle of contact between the stnker and the test piece (9.7).