DIAGRIP
Friction shims
With Friction-Increasing Washers for Maximum Power Density
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Friction Shims
Friction-Increasing Washers
Force-fit connections created with friction-increasing coatings like DIAGRIP are the key to safely and efficiently functioning force transmission systems.
With DIAGRIP FRICTION SHIMS, these functions can be integrated into any design that requires the transmission of the highest possible torques, using simple and cost-effective components such as friction discs or friction-increasing foils.
In drive technology, the automotive industry, energy technology, and wind turbines, the trend is toward increasingly compact and lighter designs, and thus also more compact flange and press-fit surfaces, which must nevertheless achieve at least the same function as previous designs. Requirements frequently exceed the usual standards, as the torques to be transmitted continue to rise due to the use of drive sources with ever-higher power densities.
Due to the trend toward compact, lightweight designs, the friction surfaces and bolted connections cannot be increased arbitrarily. This usually leaves DIAGRIP FRICTION SHIMS as the only way to achieve the desired increase in friction.
The Key Advantages of Using DIAGRIP FRICTION SHIMS:
- Increase in transferable forces by 0.5–0.8 μ
- 3 to 4 times higher transferable torque
- Reduction in component sizes
- Increase in safety factor
- Cost reduction
- Easy handling
- Insensitive to lubricants
- Reusable after disassembly
Increasing Friction
Using Different Grain Sizes
The diamonds used in DIAGRIP systems are available in 4 different grain sizes (10, 25, 35, 55 μ) and can therefore be optimally adapted to the hardness, roughness, and size of the friction surface on the flange surfaces.
The increase in friction can reach up to 0.8 μ, and by creating a so-called micro form-fit (micro-interlocking), an almost 100% force-fit connection can ideally be achieved. This allows up to 4 times more torque to be transmitted.
DIAGRIP FRICTION SHIMS and DIAGRIP friction foils can be combined in all sizes and thicknesses with any contour and can be adapted to almost any flange surface. Modern, flexible manufacturing methods enable customized solutions for individual parts and large-scale production.
Schematic representation of the friction-increasing system consisting of the dispersion layer and the counterpart of the friction pairing
Application Areas
Friction Shims in Use
Energy Technology and Mobility
DIAGRIP friction-increasing segment washers for wind turbines, DIAGRIP FRICTION SHIMS for electric drives
Automotive Industry and Engine Technology
DIAGRIP FRICTION SHIMS for camshaft adjusters, pulleys on crankshafts
Tool and Mold Making
DIAGRIP coatings for tool and mold making
Motorsport and Racing
DIAGRIP coatings for engine, transmission, and chassis components
Automation and Handling
DIAGRIP FRICTION SHIMS for robotics and handling
Application
How DIAGRIP Friction Shims Are Used
The dynamic transmission of mechanical forces and torques in machines can be achieved, among other things, by connecting the drive and machine elements through the pressing together of two (usually rotating) surfaces. Depending on the design of the machine, permanently operating but detachable, or cyclically operating transmission designs are used. Examples of this include flange connections, face-press connections, shaft-hub connections, but also bolted connections, which are generally among the permanent types. Cyclically operating systems for force and torque transmission consist, for example, of two discs pressed against each other.
In all cases, the efficiency of force or torque transmission is subject to the requirement of largely preventing friction. Among the relevant parameters of force transmission is, above all, the available surface area of the two contact partners (drive and counterpart). The more efficiently friction or slippage is prevented, the smaller and thus lighter the two contact partners can be designed structurally – increasing friction thus makes a decisive contribution to energy and material savings in plant and mechanical engineering.
The increase in friction is achieved through DIAGRIP® dispersion coatings made of chemically or electrolytically deposited nickel and nickel-phosphorus layers with embedded hard particles. Diamond, in particular, in grain sizes of about 5 μm up to 35 μm, has proven effective as a hard particle, and up to 80 μm for special applications.
Friction-increasing surfaces are used in various forms, especially in the automotive industry for crankshafts and camshafts. Premium manufacturers also use these surfaces in steering, chassis, or transmission components. Particularly high demands in motorsport demonstrate the performance capability of such coatings. They are also found in wind turbines, where they prove convincing due to the achievable savings in component mass as well as the good corrosion resistance provided by the use of the nickel-phosphorus alloy as a coating material. The use of DIAGRIP® coatings enables vibration-resistant and durable flange connections.
Characteristics
For DIAGRIP Friction-Increasing Dispersion Layers
The dispersion layers for increasing friction values are available with different sizes of polyhedral, sharp-edged diamonds. The diamond size to be used depends on the roughness of the surface of the friction pairing. The best results are achieved on surfaces with low roughness and low waviness – the result of metal processing using mechanical methods such as turning, milling, or grinding.
Both rough and wavy surfaces reduce the actual effective contact area between the friction-increasing dispersion layer and the component surfaces of the friction pairing. The following diamond grain sizes and fill levels are offered as standard:
The thickness of the nickel layer is selected so that the diamond particles protrude sufficiently far from the nickel layer, thereby reliably creating a material-locking bond with the counterpart of the friction pairing.
Another characteristic of the dispersion layer is provided by the chemically deposited nickel layer used, with phosphorus contents ranging from 1% up to 13%, available in three states:
> Low phosphorus content – 1% to 5% / high deposition hardness / lower corrosion resistance
> Medium phosphorus content – 5% to 10% / medium deposition hardness / higher corrosion resistance
> High phosphorus content – 10% to 13% / lower deposition hardness / high corrosion resistance
The phosphorus content determines the base hardness of the nickel layer, the maximum hardness achievable through heat treatment, and the corrosion resistance.
For special applications or particular shaping requirements of the friction pairing, it is possible to apply the nickel dispersion layer directly to the components used 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.
As a quality characteristic of the DIAGRIP® friction-increasing dispersion coating, the friction value for the surface can be used as a reference. However, this value depends primarily on the applied contact pressure. Typical values range between approximately
μ = 0.5 and μ = 0.8. This represents an increase in friction values compared to approximately μ = 0.3 without the use of the coatings, resulting in an increase in transferable forces or torques by a factor of 3 to 4.
Frequently Asked Questions
DIAGRIP Friction Shims FAQ
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