30/8/10 – Low Friction Diamond Like Coating Technology offered by DIARC
30 August 2010
DIARC-Technology has developed its next generation coating system which enables tetrahedral amorphous carbon, (ta-C) structured diamond-like coatings to be produced in volume quantities for industrial applications. The company says that its improved process is targeted at companies who need a hard-wearing protective coating that can deliver increased efficiency and reliability of components operating in challenging and critical wear environments in mechanical systems.
The latest generation of coatings also offers extremely low friction in the presence of lubricants so supporting reduced energy consumption. The super-lubricant coating has broad industrial applications for all types of wear parts in engines, hydraulic systems and power transmissions and also for precision tool applications. “In many cases the coated component or tool ensures a trouble free operation of the machine and the production process. On tools, for example, the improvement in service life offered by the coating plays a more important role. Also, improved quality and more efficient production gained when using coated tools is in many cases as important as the service life of the tools,” says Tapani Haikola, Vice President of DIARC.
Environmentally friendly coating process
DIARC is a pioneer in a low temperature vacuum plasma deposition process which can lay down a thin tough layer of diamond like carbon onto a range of materials from metals to plastics. The process is based on a special plasma accelerator technique to create highly ionized plasma of the coating material. The plasma is electromagnetically accelerated to a high velocity (energy), directed towards the workpiece and targeted onto the surfaces to be coated. This principle makes it possible to process well adherent dense coatings at low temperatures, typically below 100 deg C. The temperature can be adjusted by the process parameters so that it is possible to make coatings at even lower temperatures (~< room temperature). The thickness of the coating can range from a few nanometres to several micrometres, depending on the application. The coating process has low energy and raw material demands and no hazardous chemicals or gases are used in any phase of the process thus making it environmentally friendly.
The unique ta-C structured hydrogen free diamond coating developed by the company has five key properties of low friction, high hardness, excellent wear resistance, chemical inertness and high thermal conductivity. The DIARC coating process also allows the properties of the coating to be graded so that the coating properties and performance can be optimised for a specific application. “The excellent wear resistance the coating protects the surfaces as a thin layer. As a comparison one micrometre layer of amorphous diamond wears out in the same time as 1 mm of hardened steel,” notes Tapani Haikola.
On modern machine constructions the wear is, in general, well controlled and the main challenges are to prevent unexpected failures like seizure of the moving parts. This may happen in overloading conditions or when the lubrication does not work properly or lubrication ceases for some reason.
The coating ensures reliable and trouble free operation (preventing seizure) of pneumatic components such as valve actuators for process valves in chemical, oil and pulp & paper industry and on plungers of precision pumps of ventilators. In a radial piston hydraulic motor, coating the sliding surfaces of the moving parts increased the efficiency at low speeds by 30 % compared to the efficiency with normal uncoated parts, which is a dramatic improvement. In power transmissions, the friction coefficient has been reported to be 25 to 30 % less when the gear wheels are coated with DIARC Diamond coating when compared to uncoated steel gear wheels.
The company has invested in its coatings process to enable increased production capability to support customers with volume requirements. DIARC’s system is designed for coating small parts in quantity. The maximum dimensions of parts the company can coat are diameter 660 mm, length 700 mm (up to 1000 mm) and weight 250 kgs.
DIARC has hundreds of customers worldwide including some of the world’s leading tooling manufacturers and industrial machine and component companies. The company has developed solutions for power transmission, pumps, valves, bearings, hydraulics and textile machines. Large international companies like Sandvik and Metso have a long relationship with DIARC and rely on DIARC´s coatings for several demanding applications. The company’s strategy is to create long-term sustainable customer relations based on the DIARC coatings service.
Typically DIARC works by developing solutions for customers´ applications through joint R&D projects. In the production phase DIARC’s Job Coating Service is adapted to serve customers for both small batches and larger series. For serial production requirements, the solution is developed to optimally suit to volume parts coating.
Today DIARC-Technology has 60% of its Coating Service sales within the EU and Switzerland plus customers in the US, Japan and South East Asia. The coatings technology originates from the development in the late 1980s by researchers at Helsinki University and this research was later spun out as a separate company. Today it has a turnover of €1m and employs 13 people. It is engaged in an active research programme, collaborating for example in several EU projects together with other European companies, universities and research institutions.