Wear testing standardized methods

Standardized Wear Testing Methods. A list of ASTM standardized wear test methods, organized by type of wear or surface damage, is given in Table 10. This is by no means a complete list of all available test methods many nonstandardized tests developed by individual companies or research organizations are also frequently used. Oftentimes if a suitable standard test method does not exist for a specific type of wear problem, an organization may decide to develop its own internal wear-testing standards best suited to its purposes. 

The DIN method is given in ISO 464954. The principle of the machine is illustrated in Figure 11.5 a disc test piece in a suitable holder is traversed across a rotating drum covered with a sheet of the abradant, which is why it is also called the rotary drum abrader. In this way, there is a relatively large area of abradant, each part of which is passed over in turn by the test piece, so that wear of the abradant is uniform and relatively slow. In the standard method there is no provision for changing conditions from those specified, other than a lower force for soft rubbers, but it would be possible to use other abradant cloths or papers and to vary the force on the test piece. The degree of slip is 100% and it would be inconvenient to test in the presence of a lubricant. Although not versatile, the method is very convenient and rapid and well suited to quality control. 

The evaluation of erosive wear of elastomers has not been standardized, and most industries test the erosive wear by using methods designed to simulate conditions relevant to their operations. 

Modified hard-core RMs by phosphosulfurized compound. Improved extreme-pressure and antiwear properties have also been obtained with the introduction of some chemical species, such as sulfur, phosphorus or boron derivatives, into the colloidal core (Delfort et al., 1998 Inoue, 1993 Inoue and Nose, 1987). Welding loads, load wear index and wear scar diameter at 5 wt% of a CaC03 core surrounded by a calcium alkylaryl-sulfonate surfactant shell, and modified by phosphosulfurized calcium carbonate core were evaluated for calcium dialkyl dithiophosphate (CaDTP) and calcium trithiophosphate (CaTTP) with the four-ball extreme-pressure test (ASTM D2783 standard method). Both modified products exhibit improved extreme-pressure performances (welding load and load wear index), while their antiwear properties (wear scar diameter) compared to those of the original micellar substrate remain at least at the same level. 

Test candidate materials for fiiction and wear using standard laboratory tribilogical methods. 

There is currently only one standard test method in ISO devoted to the measurement of abrasion resistance for plastics materials, this being the "Taber test standardized in ISO 9352 [101]. In this test a specimen is clamped onto a turntable that rotates at either 60 rev per min (where the electrical mains frequency is 50 Hz) or 72 rev per min (where the electrical mains frequency is 60 Hz) and weighted abrasive wheels press against the surface of the te.st piece. The center of rotation of the test piece is offset from the line of contact of the wheels, and so as the former is rotated this caiuses the wheels to rotate and to wear an annular track into the specimen surface. Figure 19 gives an illustration of the test piece... 

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

Standard Test Method for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets Standard Test Method for Ranking Resistance of Materials to Sliding Wear Using Block-on-Ring Wear Test... 

Standard Test Method for Wear Testing with a Crossed-Cylinder Apparatus... 

Currently, however, quantitative assessment of the mechanical durability of non-wetting surfaces is difficult due to the diversity of wear testing and characterization methods discussed above. Ideally, the evaluation techniques should be more standardized and possibly reduced in number, as this would be beneficial for focused efforts to develop resilient coatings. From all the techniques that we described above, there seem to be some of them that are more commonly accepted. Linear abrasion, for instance, seems to be a very well accepted and is a common method to evaluate the mechanical durability. Sand, water/jet and gas impact are also good techniques to evaluate the stability of the surfaces for outdoor applications. Nevertheless, the range of possible applications for super hydrophobic surfaces may call for specialized mechanical tests like laundry tests, finger touch, etc. 

ASTM D5183-05(2011) Standard Test Method for Determination of the Coefficient of Friction of Lubricants Using the Four-Ball Wear Test Machine. 

It is clear to those who regularly perform knee wear testing, and especially those who try hard to do testing well, that the devil is in the detail . With the exception of some specialist workshops (e.g., by ASTM) even scientific conferences appear lately to be more focused on results they leave little room for detailed discussion, especially on methodological detail where most of the variability in results emanate, in the author s view. Nevertheless, this chapter is still not a detailed how-to manual. International standards (where available) are cited instead. Published international standards typically describe such methods in sufficient detail. Nor is this text a review of the results of TKR tests from the literature, as useful as that may be. The results are too many and varied only some are cited here to illustrate specific points. The main emphasis here is on matters of rationale and know-how to avoid pitfalls in the choice of test methods, in their implementation, and in the interpretation of results. This emphasis should help engineers in the orthopedic industry and in the research community who hunger for the type of detail they cannot usually find in published research papers, usually for lack of space in such result-oriented research articles. 

Standardization of the Displacement-Control TKR Simulation Method for Wear Testing... 

ASTM F732-00. Standard test method for wear testing of polymeric materials used in total joint prostheses. ASTM Int 2006. West Conshohocken, PA. 

It has been recognized that a standardized method of particle retrieval from the tissues and simulator lubricants, followed by debris characterization and quantification, is required for a uniform approach to debris response investigations. However, there are a number of different standards available from the British Standards Instimtion (BSI), International Organization for Standardization (ISO), and the American Society for Testing and Materials (ASTM), which currently offer conflicting advice for isolation of wear particles from periprosthetic tissues and simulator lubricant samples. 

The wear achieved from a sliding wear test is in the form of an annulus on the top ball and a worn circle on each of the lower three balls. A standard method of assessing the severity of wear is to measure the wear scar diameters of the lower balls and examine how this varies with increasing load. It can be seen from Figure 5 there was a sudden transformation in the wear regime at the 110 kg load. This is known as the transition region, in which the wear behaviour below is known as mild wear and above as severe wear. When the contact experiences mild wear the oil film between the contacts is intact and mainly elasto-hydrodynamic lubrication is present. When severe wear occurs, the... 

Tests Simulating Use Conditions. Several simulation tests involving wear and use testing have been developed. The first and only one to be adopted as a standard in the United States is AATCC Test Method 134-1975 for measuring the electrostatic propensity of carpets (60). In this test a person wearing standard neoprene and leather sole shoes and carrying a probe connected to an electrometer walks on a carpet for 30 to 60 s until the measured body voltage builds up to a maximum. 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quaUty. Standard test methods employed by the iadustry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeabiUty, microstmcture, Poisson s ratio, transverse mpture strength, and Young s modulus are set forth by ASTM/ANSI and the ISO. 

Further, this standard provides for methods of compliance, personal protective equipment, adequate communication of benzene hazards to employees, regulated areas, and medical surveillance of workers who are or may be exposed to benzene. Any employee routinely exposed to benzene should, in addition to wearing protective equipment, receive periodic blood tests. 

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