Friction locking connections with friction-coefficient increasing coatings like DIAGRIP are the key for safely and efficiently functioning power transmission systems. 

With the DIAGRIP FRICTION SHIMS, these functions can be integrated with simple and cost-effective components as  shims or friction-coefficient increasing films in every design involving the transmission of the highest possible torques. 

The trends in drive technology, the automotive industry, energy technology and in wind turbines are for ever more compact and lighter designs, and therefore also more compact flange and tight-fit surfaces, which still have to achieve the same function as with previous designs. The requirements frequently exceed what is otherwise normal, as the torques to be transmitted are constantly increasing through the use of drive sources with ever higher power densities. 

As a result of the trend for compact, lightweight designs, the friction surfaces and screw connections can no longer be increased correspondingly as desired. As a result, the desired increase in friction coefficient can mostly only be achieved with DIAGRIP FRICTION SHIMS. 

The diamonds used in the DIAGRIP systems are available in four different grain sizes

(10, 25, 35, 55 μ) and thus can be individually adjusted optimally to the hardness, roughness and size of the friction surface on the flange surfaces. 

The increase in friction coefficient can reach up to 0.8 μ and, through the production of a so-called micro-form fit (micro-interlocking), almost 100% traction can be generated optimally. Consequently, up to 4 times more torque can be transmitted. 

DIAGRIP FRICTION SHIMS and DIAGRIP friction films in all sizes and thicknesses can be combined with any desired contour and can be adjusted to almost all flange surfaces. Modern, flexible production methods allow tailored solutions for individual parts and large series. 


Increase in power transmission by
0.5 – 0.8 μ  

+ 3 to 4-times higher transmitted

+ Reduction in component sizes

+ Increased safety factor

+ Costs reduction

+ Increased safety factor

+ Easy to use

+ Not sensitive to lubricants

+ Reusable after dismantling

+ Use without modifications

Schematic representation of the friction-enhancing system consisting of dispersion layer and counterpart of the friction pairing


Areas of Application

energy technology & E-mobility

DIAGRIP friction coefficient-increasing segment shims for wind turbines, DIAGRIP FRICTION SHIMS for electric drives 


DIAGRIP FRICTION SHIMS for camshaft timers, Belt pullets on crankshafts


DIAGRIP coatings for tool and mould construction 


DIAGRIP coatings for engine, transmission and chassis components 

Automation & Handling

DIAGRIP FRICTION SHIMS for robotics and handling 


The dynamic transmission of mechanical forces and torques in machines can be achieved, among other things, by connecting the drive and machine elements by pressing two (usually rotating) surfaces onto each other. Depending on the design of the machines, permanently working but detachable or cyclically working transmission designs are used. Examples include flange connections, face press connections, shaft-hub connections, but also screw connections, which are usually permanent. Cyclically operating systems for power and torque transmission, for example, consist of two discs pressed onto each other.

In all cases, the efficiency of the power or torque transmission is subject to the requirement that friction is largely eliminated. The relevant parameters of power transmission include, above all, the available surface area of the two contact partners (drive and counterpart). The more efficiently friction or slip is prevented, the smaller and thus lighter the two contact partners can be designed to be – increasing the coefficient of friction thus offers a decisive contribution to energy and material savings in system and machine construction. The increase in the coefficient of friction is achieved by DIAGRIP® dispersion coatings of electrolessly or electroplated nickel and nickel-phosphorus layers with embedded hard materials. Diamond, in particular, has proven itself as a hard material in grain sizes from about 5 μm up to 35 μm, for special applications also up to 80 µm.

Friction-enhancing surfaces in various forms are used primarily in the automotive industry for crankshafts and camshafts. Premium manufacturers also use these surfaces in steering, chassis or gearboxes. Fulfilling particularly high requirements in motor sports is proof of the performance of such coatings. Furthermore, they can be found in wind turbines, where they perform well due to the achievable savings in component mass, as well as the good corrosion resistance through the use of the nickel-phosphorus alloy as a coating material. DIAGRIP® coatings can be used to construct vibration-resistant and durable flange connections.


The dispersion coatings for increasing the coefficients of friction are available with different sizes of polyhedral, sharp-edged diamonds. The size of the diamonds to be used depends on the roughness of the surface of the friction pairings. The best possible results are achieved with surfaces with low roughness and low waviness – the result of metal processing by mechanical methods such as turning, milling, grinding.

Both rough and wavy surfaces reduce the actual effective contact area between the friction-enhancing dispersion layer and the component surfaces of the friction pair. The following diamond grit sizes and filling grades are offered as standard:

Functional properties Friction-enhancing DIAGRIP® diamond coating
Designation DIAGRIP® 10 DIAGRIP®25 DIAGRIP®35
Average particle size 10 μm 25 μm 35 μm
Coating rate 15 % and 30 % 15 % and 30 % 15 % and 30 %
Layer material Chemically deposited nickel-phosphorusor electrodeposited nickel or nickel-phosphorus
Hardness of coating matrix 550 – 950 HV0,1
Layer thickness of the matrix (electroless nickel) 5 – 8 μm 13 – 17 μm 14 – 22 μm
Layer thickness of the matrix (electroplated nickel) bis zu mehreren hundert Mikrometer
Base material for discs and foils Copper, copper with insulating intermediate layer, steel and spring steel from 0.05 to several millimetres material thickness

The thickness of the nickel layer is selected so that the diamond particles protrude sufficiently far from the nickel layer and can thus reliably create a material bond with the counterpart of the friction pairing. Another parameter of the dispersion layer is provided by the electrolessly embedded nickel layer used with phosphorus contents between 1 % and up to 13 %, available in three state forms:
> Low phosphorous content  – 1 % to 5 % / high deposition hardness / low corrosion resistance
> Medium phosphorous content5 % to 10 % / medium deposition hardness / high corrosion resistance
> High phosphorous content10 % to 13 % / low deposition hardness / high corrosion resistance

The phosphorous content determines the basic hardness of the nickel layer, the maximum hardness that can be achieved using temperature treatment, and the corrosion resistance.



For special applications, or for special shaping needs of the friction pairing, it is possible to apply the nickel dispersion layer directly to components to create the friction pairing. It is strongly recommended to coordinate the choice of materials and the shaping with the manufacturer of the nickel dispersion layer.

The coefficient of friction for the surface can be used as a characteristic value for the quality of the friction-enhancing dispersion coating DIAGRIP®. However, this value depends primarily on the applied contact pressure. Usual characteristic values are between about μ = 0.5 and μ = 0.8. This results in an increase in the coefficient of friction compared to about μ = 0.3 without the use of the layers which causes an increase in the transmittable forces or torques by a factor of 3 to 4.


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