Wear mechanisms of UHMWPE under physiological conditions
In 2005 one of the giants in implant manufacturing launched the most flawed metal on metal implant. It caused a loss of billions of dollars and more than 8000 patients were forced to a revised surgery because of the high health hazard. At present, polymer on metal implants comprise of 70% of all hip and knee arthroplasty. Increased life expectancy and lower revision surgeries due to wear induced osteolysis are driving development of superior grades of UHMWPE. Since 1970s, the procedure for the development of new orthopaedic bearings initiates with screening of several candidate ... Read More
Category: Application Notes
Soft contact tribology is at the heart of our feelings perceived as moistness, smoothness and comfort. Although there is no standard definition, the study of friction behavior of low modulus materials could qualify as soft contact tribology. Lately, several studies have highlighted the benefits of soft contact tribology in improving our perception of feelings, through engineering the materials that we touch.
Friction (or shear stress) connects the mechanical action like touch with the psychological reaction such as smoothness feeling. A representative friction curve for the soft contacts is given in Figure 1.
Few important features in this curve are static friction ... Read More
Importance of Friction Measurement during ASTM G65 Abrasion TestingIt is well known that both energy efficiency and productivity are critical for large scale industrial operations. Components such as molds and dies used in powder metallurgy industry and jaws, hoppers, chutes, pumps in mining and cement industry are affected by abrasive wear during raw material handling. Advanced steel grades (with bainite-martensite-carbide microstructure, Hadfield steel) and surface engineering solutions (WC-Co, Cr3C2) offering 10X higher wear resistance have improved productivity and reduced maintenance cost. However, the overall energy efficiency, driven by the electric/diesel power consumed during such operations is ignored. Frictional resistance between ... Read More
DLC coating to neutralize fretting of dental implant componentsThe success of two-piece dental implants (Figure 1) is threatened by fretting occurring between the ceramic abutment and the titanium-based fixture. A wrong design could generate mismatches between surfaces and a poor choice of materials would result in excessive micromotions between abutment and fixture. Sliding and fretting wear cause a disproportionate ion release in the surrounding tissues, potentially giving the gingiva a greyish appearance. The lost material enlarges the existing microgaps exposing the implant to bacterial colonization and infections. The extreme consequences of these processes result in the removal of the implant ... Read More
Realistic shearing conditions using Extreme Load TribometerIn general, tribometers used in the labs have contacts largely scaled down compared to friction contacts in the real field conditions. It has resulted in several key advantages for the users including short test duration, lower cost of testing, improved test repeatability and ease of testing. However, the largely scaled down contact conditions may not simulate the real life shearing state of lubricants. This often translates into reports with unrealistic friction and wear.
Figure 3. Temperature (A) and friction (B) profiles of engine oils with viscosity index (VI) of 163 and 124.Figure 1. Description ... Read More
Tribology in MiningAn example of friction and wear process during extraction, materials handling, and material processing is shown in Figure 1. Damages to the materials used for drilling or digging are a result of impact, erosive and abrasive contact with the earth surface. Materials used in crushers are faced with severe impact and abrasive contact with the large chunks of minerals. Mining trucks with lubricated engine components and other power transmission systems, used for materials handling are subjected to lubricated wear. In cases, where the size of the particles is in few mm, the transportation of minerals is made ... Read More
Solid particles in dusty environments can damage materials and affect dimensional tolerances in variety of industries ranging from gas turbines, helicopter rotor system (aerospace applications), boiler tubes (coal power plants) and wind turbines (renewable energy). Erosion of certain components can reduce operational efficiency of systems and have economic impact.