Impact Testing üCompressive properties describe the behaviorof a material when it is subjected to a compressive load. üLoading is at a relatively low and uniform rate. üCompressive strength and modulus are the two most common values produced. Compression test üBlocks or cylinders üFor ASTM D695: +The typical blocks: 12.7 x 12.7 x 25.4mm +The cylinders:12.7mm diameter and 25.4mm long üFor ISO 604: the preferred specimens: +50 x 10 x 4mm for modulus +10 x 10 x 4mm for strength Specimen size: Scope: üThe specimen is placed between compressive plates parallel to the surface. üThe specimen is then compressed at a uniform rate. üThe maximum load is recorded along with stress-strain data. üAn extensometer attached to the front of the fixture is used to determine modulus. Compression test Compressive strength maximum compressive load minimum cross-sectional area = Compressive modulus change in stress change in strain = Test Procedure: Rockwell Hardness tester üStandardspecimen of 6.4mm thickness ü is moldedor cut from a sheet. Specimen size: ü A hardness measurement based on the net increase in depth of impression as a load is applied. üHardness numbers have no units and are commonly given in the R, L, M, E and K scales. üThe higher the number in each of the scales, the harder the material üThe harder the material → better resistance to plastic deformation or cracking in compression, better wear properties Scope: DurometerHardness -Shore Hardness üDetermine the relative hardness of soft materials, usually plastic or rubber. üThe test measures the penetration of a specified indentorinto the material under specified conditions of force and time. üThe hardness value is often used to identify or specify a particular hardness of elastomersor as a quality control measure on lots of material. Scope: üGenerally 6.4mm (¼in) thick for ASTM D 2240. Specimen size: DurometerHardness -Shore Hardness üThe specimen is first placed on a hard flat surface. üThe indentorfor the instrument is then pressed into the specimen making sure that it is parallel to the surface. üThe hardness is read within one second (or as specified by the customer) of firm contact with the specimen. Test Procedure: üThe hardness numbers are derived from a scale. üShore A and Shore D hardness scales are common, with the A scalebeing used for softer and the D scale being used for harder materials. Data: ü Density is the mass per unit volume of a material. ü Specific gravity is a measure of the ratio of mass of a given volume of material at 23°C to the same volume of deionizedwater. üSpecific gravity and density are especially relevant because plastic is sold on a cost per pound basis and a lower density or specific gravity means more material per pound or varied part weight. Density and Specific Gravity ASTM D792, ISO 1183 Scope: ü For sheet, rod, tube and moldedarticles. üThe specimen is weighed in air then weighed when immersed in distilled water at 23°C using a sinker and wire to hold the specimen completely submerged as required.Density and Specific Gravity are calculated. üAny convenient size +Specific gravity = a/[(a + w)-b] a = mass of specimen in air. b = mass of specimen and sinker (if used) in water. W = mass of totally immersed sinker if used and partially immersed wire. +Density, kg/m3= (specific gravity) x (997.6) Test procedures: üBulk density is defined as the weight per unit volume of material. üBulk density is primarily used for powders or pellets. üThe test can provide a gross measure of particle size and dispersion which can affect material flow consistency and reflect packaging quantity. üA funnel is suspended above a measuring cylinder. üThe funnel is filled with the sample and allowed to freely flow into the measuring cylinder. üThe excess material on top of the measuring cylinder is scraped off with a straight edge. üThe sample and the cylinder is then weighed and the weight / volume (Bulk Density) is determined. üApparent density value is recorded as g/cm 3 Bulk Density ASTM D1895B . test üBlocks or cylinders üFor ASTM D6 95: +The typical blocks: 12.7 x 12.7 x 25. 4mm +The cylinders:12.7mm diameter and 25. 4mm long üFor ISO 604: the preferred specimens: +50 x 10 x 4mm for modulus +10. specified conditions of force and time. üThe hardness value is often used to identify or specify a particular hardness of elastomersor as a quality control measure on lots of material. Scope: üGenerally. per pound basis and a lower density or specific gravity means more material per pound or varied part weight. Density and Specific Gravity ASTM D792, ISO 1183 Scope: ü For sheet, rod, tube and