Wear test apparatus

Wear-Testing Apparatus and Experimental Procedures. To study the effect of temperature on the wear behavior of specimen polymers, the pin-on-disk type wear testing apparatus used in our previous work (] J was employed and the frictional force and wear depth of the flat ended polymer pins 3 mm in diameter were measured at a sliding speed of 0.1 m/s under a load of 10 N and at various experimentally possible disk temperatures up to 300. The disk was made of stain-... 

The specimen is a diamond-shaped obstruction in the center of a flow channel. A commercial wear test apparatus based on this geometry is the Tribotest from Bra-bender OHG in Duisburg, Germany. This test is often referred to as the Siemens-Method wear test. Eichler and Frank [6] modified this test to make it more suitable for injection molding. Entirely different test geometry was developed at the DKI (Deutsches Kunststoff Institut, Darmstadt). This test utilized a flat plate geometry as shown in Fig. 11.6. 

The pin-on-disk test (13) is not a standard for plastic wear testing, but it is the only wear test apparatus t many laboratories have and thus it will be used for plastic, metal, ceramic, etc. It works quite well if this tribosystem simulates the real-life tribosystem of interest. The rider in the pin-on-disk test is usually a ball or a hemispherical-ended pin. Flat-ended pins are used, but they often hydroplane and do not wear flat. Plastic testing laboratories often have molds for flex bw and tensile samples. Ball cavities can easily be put in these same molds to provide molded spheres as riders for a pin-on-disk test. The disk can be made from any counterface of interest. It is particularly easy to measure wear volume from spherical surfaces. A simple calculation using the diameter of the flat worn on the sphere will produce a wear volume measurement that is usually more accurate that can be obtained by mass change measures. This te excels for simulating tribosystems that involve very small normal forces on the plastic member. 

Figure 8.18 Schematic iiiustratfon of abrasive wear resistance testing apparatus...

Instruct others to maintain a safe distance. Wear breathing apparatus, eye protection, laboratory coat, and nitrile rubber gloves. Cover the spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. When the bromine has been absorbed, quickly scoop into a plastic pail and, in the fume hood, very slowly add the mixture to a pail of cold water. Add 10% sodium bisulfite until solution turns colorless. Test the pH and neutralize if necessary with sodium carbonate. Decant the solution to the drain. Treat the solid residue as normal refuse. Wash the spill area thoroughly with soap and water.20... 

When an automotive chemist chooses a polymer for dynamic sealing, he or she will have to consider the conditions present in Table 6.1. The two main polymers utilized today for these applications are the thermoset polyimides and polyetheretherketones. Polytetrafluoroethylene is also used for less severe applications. Wear test data are collected on an apparatus in which three circular pins of the polymer being examined... 

Testing. In order to measure the wear flat diameter of the truncated cone, steel pins are fixed in test apparatus scratching against a... 

ASTM G99-04 Standard test method for wear testing with a Pin on Disk apparatus, ASTM (2004). 

G83 Test Method for Wear Testing with a Crossed-Cylinder Apparatus (vol. 3.02, p. 339-344, 1995)... 

G99 Test Method for Wear Testing with a Pin-on-Disk Apparatus (vol. 

The rough surface was produced by an abrasive wear process as shown in Fig. 1. The experimental conditions of the abrasive wear process were as follows. The size of specimen was 60 x 35 x 5 mm. The abrasive wear test was conducted on the turnplate abrasive wear test machine made by the Chinese Research Academy of Agricultural Machine (model JMM). The mixture comprised of 450-900 pm quartz sands 94 wt%, bentonite 3 wt%, and water of 3 wt% was used as abrasive to wear the specimens. The buried depth of the specimen was 40 mm (see Fig. 1). Three test material specimens (samples 1-3 in Fig. 1) and one comparative material specimen (sample 4 in Fig. 1) were fixed on the clamping apparatus at the same time. During the wear process, the specimens did not move, the turntable turned at 45 rpm causing the abrasive to move. This resulted in a relative movement between the specimen and the abrasive at the speed of 123.6 m/min. By means of the intermittent rotation of the clamping apparatus, every specimen from sample 1 to sample 4 was in turn located at the wear position at which the specimen was just buried in the abrasive to be worn. At the wear position the wear distance of each sample in each wear turn was 803.4 m ( wear distance is the distance of the relative movement between the specimen located at the wear position and the abrasive). Total wear distance of each specimen was 16068 m. 

Stoll-quartermaster universal ware tester n. A versatile testing apparatus for measuring wear resistance of fabrics, yarns, thread, etc. It can be equipped with either of two testing heads, one for testing abrasion resistance of flat surfaces and the other for testing resistance to flexing and abrasion. 

A molten or liquid mass of polymer is forced onto a test specimen, from which it is deflected the material exits through a small clearance of 0.4 mm. This test device gives relatively quick results. Disadvantages are the complex geometry of the clearance, non-uniform flow conditions at the specimen, and that increased wear changes the resistance to flow and thus the wear conditions. Another method was developed by Bauer, Eichler, and John [5] in 1967. Figure 11.5 shows the geometry of their test apparatus. 

The rectangular test gap has a length of 12 mm, a width of 10 mm, and a height that is adjustable from 0.1 to 1.0 mm. This geometry has been used for studies with thermoplastics [7] as well as with thermosets [8]. A modification of the flat plate wear tester is the BASF wear tester. This test simulates the wear process in a molding machine. Another test apparatus developed at the DKI is the ring method, shown in Fig. 11.7. 

Other tests have been described by Mosle et al. [16] and Maelhammar [17]. The latter test is a combination of metal-liquid wear and corrosive wear. The apparatus was modified by Volz [18] for thermosets. The volatiles are extracted from the polymer melt, which has been prepared in an injection molding machine and has been sheared through a test gap. Through electrochemical measurements, Volz could prove that significant differences exist in the corrosive action of volatiles separated from injection molded samples of thermosetting polymers. 

Tests for metal-to-metal wear can utilize the standard test methods, provided the proper intermediate material can be introduced between the metallic surfaces. Bros-zeit utilized the cylinder-disk apparatus to study metal-to-metal wear [19]. Saltz-man, et al. [20-22] used the Alpha LFW-1 test apparatus see Fig. 11.9. 

No person shall enter or remain in a confined space in which the proportion of oxygen in the air may be substantially reduced unless he is wearing breathing apparatus or the space is adequately ventilated, tested and certified as safe. 

Wear tests are conducted with a thrust-washer test apparatus. A sample thrust washer is mounted in an antifriction bearing equipped with a torque arm (see Fig. 3-105) [323]. The test-specimen holder is drilled to accept a thermocouple temperature probe. The raised portion of the thrust washer bears against a dry, cold-rolled, carbon-steel wear ring with a 12- to 16-microinch finish at an 18 to 22 Rockwell C scale hardness at room temperature. Each evaluation is conducted with a new wear ring that has been cleaned and weighed on an analytical balance. The bearing temperature and friction torque are continuously monitored. 

Figure 3-105. A washer-test apparatus to determine the wear, friction, and limiting PV for molding compounds.

The coefficient of friction data in Table 3-7 were obtained with the thrust washer test apparatus. The test specimen is run in against the standard wear ring until 360-deg contact between the raised portion of the thrust washer and wear ring is made. Temperature of the test specimen is then allowed to stabilize at the test conditions (generally 40 psi, 50 ft/min, room temperature, and dry). After thermal equilibrium, the dynamic frictional torque generated is determined with... 

The previously mentioned tests that can be used to determine if a plastic is abrasive to other surfaces are not particularly suited to evaluation of the abrasivity of plastics that are normally manufactured as flexible webs. Web materials with thicknesses less than about one millimeter pose the problem that they usually need to be adhered to some other surface to allow testing them as bushings, thrust washers, or blocks for block-on-ring tests. This can be done and is done, but two other tests Imve been developed that are particularly useftil for web materials the ball-on-plane test and the tape abrasion test (14). The ball-on-plane test, lich is shown schematically in Figure 8, reciprocates a spherical rider on a web test sample while the sample rotates slowly at less than 1 revolution per minute. The rider would see mostly fresh surface if allowed to run only one revolution, but in practice this test is usually run for longer test durations (from 10 minutes to 40 hours). When the test is run for more than an hour, the web counterface is changed every hour the rider is simply lifted off the test surface. Volume loss on the ball rider is the test metric. Wear volume is measured from the ball scar diameter and this measurement can be made in situ on the test apparatus. 

The bearings were replaced and the test resumed. At the end of 686 hours the test apparatus shut itself off when the liquid level ran low. The bearings were again removed and inspected for wear. The balls in both the upper test bearing and the support bearing showed from 0,006 inch to 0,007 inch wear. 

---