The standard method for evaluating anti-wear of hydraulic fluids in a vane pump, is by the 100 hour ASTM or 250 hour ISO method, using a real Conestoga-built vane pump. This method takes a long time to run, and requires a lot of fluid. This makes it difficult to use the method for development or research.
Various types of polymers can be used on steel cables, to provide a controlled-friction and noise-reducing coating when used on pulleys. An efficient way to prescreen the behaviour of different types of polymers, in terms of frictional stability and durability, is needed.
In everyday life people use hairstyling products such as waxes or gels, to improve the holding of hair and improve/change its appearance. However, in the market there are many products available, claiming to have different characteristics (e.g. strong hold, silky/smooth touch…). To define the performance of such products, tribology comes into play. In particular two parameters are important. The friction determines how easy a wax or gel can be applied, whereas the stickiness and tackiness determine their holding ability.
Wiper blades are of great importance to the safety of the driver. In reality they can operate under different speeds (various scales in the car) or under different lubrication conditions (from dry to wet with thin or thick film of water). To simulate these conditions in lab scale you need to have a versatile apparatus and you will need to use the actual components to be as close to reality as possible.
Nowadays polymer based coatings are applied in all walks of life, due to their excellent corrosion resistance, low friction and cost, good surface finish, molding ability and low density. However, one of the main issue of these coatings is their relatively poor performance in terms of wear. Especially, when sliding under high speeds, frictional heating can lead to a softening of the coating and accelerate the wearing-off process. Evaluating the high speed sliding performance of polymer coatings is a key issue in many applications.
A variety of oils for the automotive industry is available in the market. These oils have different composition, additives and can operate under different conditions (motion, load, speed and temperature). A method need to be used to prescreen the performance and endurance of these oils under different conditions, which are relevant to the automotive industry.
In everyday life we come across and use applications were wires are operated in sliding contacts. Some examples are elevators, car doors, canopies etc. In the majority of these applications, friction is critical (e.g. the wire in a canopy should slide smoothly), and after a period of tuse, wear damage of the wire can also obstruct the performance.
One issue in the pharmaceutical industry, is the abrasion of processing components for pressing the powders. The intensity of the abrasion phenomena strongly depends on the composition and size of the processed powders. Up to date there is no fixed procedure on how to evaluate such abrasion phenomena, in conditions that simulate the realistic process.
The steering system of cars is based on a rack and pinion system. Over time, the metal on these gears wears out, resulting in a loose fitting. Some other applications also make use of a rack and pinion system to translate a rotary drive motion into a linear displacement. The wear and tear of such systems occurs through a roll-slip mechanism. Therefore a tribological method needs to be developed to simulate such roll-slip contacts and their failure mechanisms.
Shock absorber component testing is expensive and time-consuming and this is a limiting factor in developing new materials for this application. There is a need to develop a pre-screening method to get a quick but accurate evaluation of the tribological behavior of materials, without losing too much correlation with the actual conditions (geometry, wear mechanism, load, speed, number of cycles etc.).
Nowadays there is a great demand to use lightweight materials, such as aluminium alloys. One of their application possibilities is in the forming industry. In such demanding applications the use of a cutting fluid is essential to lubricate cutting edge and cool down the workpiece. Until now, to evaluate the efficiency of cutting fluids, ASTM D3233 tests on a Falex Pin-and-Vee Block tester were performed. However, this procedure was developed on hard tool steels and thus it is not appropriate for soft materials, such as aluminum alloys. In this application study and a modification of this procedure is proposed for testing of cutting fluids for soft materials and alloys.
One of the most difficult industrial issues related to tribology is the prediction of long term wear or material durability. In many components and products, materials with or without lubrication are used to reduce wear and maintain functionality of the component. Required ‘wear life’ may be thousands of hours. Contrary to the determination of a ‘coefficient of friction’ – which can be done in a few hours, the determination of wear and wear rate under realistic conditions is a long term test. The challenge is twofold : perform low wear rate experiments with many repeats at an economically acceptable cost. The only way to do this is by a multistation approach (performing many wear experiments simultaneously).
Parallel tests were performed in our TRL6 prototype 10-station cross-cylinder block-on-cylinder tester. With this method, we test parallel and simultaneously different bulk or coated materials (metals, alloys, polymers, ceramics and composites), at moderate contact pressures and for a prolonged period of time. Adhesive or mild abrasive wear mechanisms are representative for the “actual” applications.
Up to 9 kilometers of sliding distance can be realised in a single day, on 10 wear contacts simultaneously.
To measure the wear damage, we use weight loss measurements, optical and/or confocal microscopy. 10 data points collected efficiently
Efficient screening showed
The wear of various materials can be measured in a time efficient and economical way, realistic wear rates simulate actual applications.
Statistical analysis of the wear data provides a higher confidence level and allows outlier analysis.
Reliability testing of materials becomes economically possible.
Polymer based composites are considered as one of the most important engineering materials for naval applications. They can be used in the superstructures, decks, bulkheads, advanced mast systems, propellers, propulsion shafts, rudders, pipes, pumps, valves, machinery and other equipment on large ships. In the majority of these applications these composites are subjected to mechanical loading in a corrosive environment. Thus their performance and/or lifetime is strongly dependent on both of these factors. In this application a methodology was developed to evaluate the effect of the corrosive environment (seawater) on the tribological performance of composite polymers is sliding contacts.
One of the main issues in the watch industry is reduce the friction and sticking between moving components. To achieve this, a small quantity of lubricant is added in the contact. However, due to the high expectations of the costumers, the increased lifetime of the watch, the size and geometry of components and contact conditions (loads in the mN range), there is a huge need to develop a tool that can evaluate such lubricating tribo-systems. The main challenge is to perform precision frictional measurements, in conditions that simulate the “actual” application.
During the processing of bricks in the construction industry, clays slurries can adhere (stick) to mechanical components such as mixers, hindering their function. In addition, in the drilling industry severe damage of the drills can be caused by the sticking and swelling (due to water adsorption) of soils onto the drills. A methodology needs to be developed to measure the stickiness of clays/soils on metallic components.
Polymeric materials are used more and more as cage material for light weight bearing applications, but thermoplastic materials suffer from PV limits. At high speeds, the polymer may melt easily under light loads. Thermoset resins don't have this limit, but may still disintegrate under higher temperatures. In this method, we can apply high speeds and variable loads, to explore the limits of thermosets.
In the effort to reduce CO2 exhaust, an important approach is to reduce friction in the engine. One part of the mix of options are ‘friction modifying additives’, such as the well-known GMO, which are known to reduce friction by 5, 10 or 20%. However, the difficult task is to prove the effect of friction modifiers in the engine, since existing engine tests measure the interaction of all sliding and moving components, as well as lubricant viscosity and other effects. In order to isolate and evaluate the efficiency of friction modifiers, a precision frictional approach is required.
The reliability of industrial equipment, transportation systems, nuclear and conventional power plants etc. can be significantly influenced by surface phenomena such as corrosion and wear. With the increasing pressure on development time and the need for higher performance, there is also an increasing need to measure and quantify the degradation phenomena faster and better. In this perspective, nuclear activation technology - as already used in engine testing- can provide accurate in-situ measurement and precise monitoring of wear, mass transfer, corrosion and erosion.
High temperature tribological testing often requires the development of complex mechanical setups, that should meet rigorous standards and specific performance metrics. Thus, the development of a state-of-the-art experimental setup to study the reciprocating sliding behaviour of various bulk and coated materials at temperatures that can reach up to 1000 °C is needed, especially for the evaluation of high temperature materials for aeronautical applications.
Evaluating frictional and wear characteristics of very thin nanostructured layers with macro scale tribometers, in the Newton load range, can create unrealistic conditions. Wear phenomena are highly dependent on the contact conditions: such high loads are not relevant in the case of MEMS. The adhesive and capillary components that contribute to friction, in a micro-contact, can not be simulated with high load devices. Therefore, there is an increasing need to use new tribological testers and procedures to obtain a better understanding of surface interactions on an appropriate scale.
Skin creams are commonly used to improve skin health and create a smooth, soft, and moist perception. This is achieved by altering the surface roughness, friction, and adhesion of skin surface. Despite the fact that there are many commercial creams available, there is no consistent scientific approach to determine their frictional and adhesive properties.
The failure of the hip replacement is often a combination of tribocorrosion of the hip joint materials and inflammations due to wear particles in the body. A new methodology needs to be developed so as to allow for a fast prescreening of the reliability of new biomaterials, in conditions that simulate the actual conditions (e.g. environment, motion, contact pressure, countermaterial).
Lubricating greases are used in various industrial fields ranging from food, transportation, aeronautical, construction, mining and steel industry. The aim is to decrease frictional forces and to protect industrial components from wear and/or corrosion damage. Their performance depends on interaction properties like adherence to the substrate, cohesion or consistency, and tackiness. However, up to date there is no established quantitative methodology that can be easily applied to efficiently and accurately evaluate the adhesion and tackiness of a grease.
In reality, due to a misalignment, vibrations or other reasons high speed pump rotors can come in contact with the stator, leading to a catastrophic failure. This failure is a result of severe shearing of the contacting surfaces. However, the existing ASTM Galling method (G 196), is performed at very high pressures and very low speeds, and does not simulate the “actual” conditions met at high speeds.
Examples of corrosion are found in many industrial applications ranging from aeronautical, automotive, naval, and the construction industry over home appliances, water systems, pipelines, and ‘bio’ applications. Corrosion phenomena can be significantly accelerated by the simultaneous occurrence of a mechanical load on the surface: the formation of cracks and surface defects, along with surface strain and stress fields lead to faster diffusion of corrosive ions or the destruction of protective layers (depassivation). Thus there is a need to understand the synergy between wear and corrosion.
Air conditioner compressor fluids have to prevent friction and wear under elevated gas pressure. Standard Pin&Vee Block tests with gas 'bubbling' through the lubricant do not correlate with field behaviour, especially with CO2 as the cooling medium. Another simulation with pressurized gas is needed. We selected the Falex Block on Ring configuration, as it also recreates the line contacts and is able to work at higher speed than the Pin&Vee block machine.
Our Falex Block on Ring machine allows pressurizing the lubricant chamber with a gas, up to 10 bar. Standard block-on-ring tests are done with and without pressure on the dissolved gas. Tests with increasing contact loads (EP) and tests with constant load (Anti-wear) are done.
A sudden loss of lubricity in the CO2 pressurized oil bath can be measured. Block temperature increases suddenly at 70°C, while lubricant temperature decreases, which indicates that CO2 bubbles are forming in the interface between block and ring. This phenomenon is only seen when the gas is dissolved under pressure in the lubricant.
This leads to poor lubrication and increased wear. Thanks to right additives, this bifurcation can be eliminated and wear prevention can be significantly improved under pressurized conditions.
Surgical suture, holding body tissue together after an injury or surgery, is a complex product. The thread can be surface treated or coated for a number of reasons. One of them is to facilitate the insertion through tissue, the other to hold the knots tightly. Friction of the suture over skin, is thus important to control. Measuring skin-suture friction allows improvement of these threads and their surface treatment.