TFC Disc Springs

TFC Disc Springs are conically formed annular discs which are loaded axially and provide a predetermined force at various operating heights.

Because of the flexibility by which they can be assembled, either singly or in columns, TFC Disc Springs are able to offer designers specific spring characteristics dependent upon how they are arranged. With their largely self damping characteristics, low operating heights, lack of setting or fatigue under normal loads and stresses, they are ideal for a wide range of static and dynamic applications. TFC Disc Springs are manufactured to recognised DIN standards and are available in a wide range of materials to suit even the most hazardous applications.

Technical Information

Disc Springs are conically formed annular discs which are loaded in the axial direction, either singly or in columns or stacks, guided on a shaft or assembled inside a cylinder. Disc Springs may be subjected to static or dynamic loading and can be designed to provide various force/deflection characteristics. Single disc scan be stacked in a variety of ways to further widen the force/deflection response available to the designer. For the above reason Disc Springs can offer several distinct advantages over other types of spring. Notable amongst these are: Linear, regressive or negative spring characteristics. High force for small spring deflection. Better volumetric efficiency i.e. space saving. High damping capacity (especially when parallel stacked). Longer service life. Simplified inventory.

Cone height ho (ho = Maximum Deflection for Disc Springs without Contact Flats)and thickness govern the force/deflection characteristics. The diameter ratio (De/Di) also influences the force/deflection curve but in a more complex way. Generally as the force required increases a larger diameter disc will be required. All the force values shown in this catalogue are calculated from the theory by Almen and László. As this is a mathematical model, deviation from these values can be expected, particularly at deflections below 0.15 ho and greater than 0.75ho. This difference will be further exaggerated due to friction effects when springs are stacked. These frictional effects (hysteresis) are more pronounced for parallel stacked springs and are useful for damping purposes. However for dynamic applications these effects are unwanted. Therefore in these situations the number of springs should be limited to 3 and this number in series to a stack length equivalent to 3x De.

Guiding and alignment are crucial when using disc springs in stacks. Guiding on a shaft is to be preferred. Both guide and abutments should have a surface hardness of 55 Rc minimum (Rc=Rockwell C Hardness test used to calculate the hardness of steel) and a surface finish of 4 micrometers Ra maximum. In order to minimise friction the stack should be lightly preloaded on the guide and the individual springs then carefully aligned.

Our standard series Disc Springs offer a reliable cost effective alternative to DIN 2093 range, conform to DIN 2093 dimensions and load characteristics but differ in that pre-setting is not performed as a routine operation. Settlement will therefore occur in the first few operating cycles and should be allowed for. Pre-set springs can be supplied but should only be specified for arduous dynamic applications.

Materials and Finishes

Manufactured from either BS1449 Pt1CS70 or DIN 17222 50CrV4, deburred so that all edges are rounded. Conform to DIN 2093 dimensions and load characteristics. Heat Treatment All Disc Springs are austempered to provide the optimum blend of ductility and hardness in the range HRC 42-52.

Finish

The standard finish for Disc Springs is commercial phosphate coating and oil dipped. Mechanical and Electro Zinc plating can be supplied at extra cost. Mechanical Zinc is the preferred process as it totally eliminates the possibility of hydrogen embrittlement.

Spring Combinations

In applications requiring Disc Spring stacks the discs may be arranged in many ways. For individual discs stacked in the same direction (parallel stacking) the deflection (travel) is that of a single disc used in the stack and the load is proportional to the number of individual discs. Hysteresis increases with the number of discs stacked in parallel. With individual discs placed in alternating arrangement (series stacking)the load is that of the single disc and the deflection (travel) is proportional to the number of discs in the stack.

Our comprehensive standard range of Disc Springs, which conform to DIN 2093 dimensions/load characteristics, are produced from BS1449 Pt 1CS70 or DIN 17222 50 CrV4 material and fully deburred so that all edges are rounded. They offer a reliable cost-effective alternative to the DIN 2093 range and will provide acceptable performance in all but the most arduous applications. Should you require more information regarding suitability for your application please contact our technical sales desk.

• Disc Spring Benefits
• Takes up manufacturing tolerances
• Quietens bearings
• Reduces numbers of components and simplifies fitting
• Minimises axial space
• Small load change with axial deflection
• Automatic bearing alignment by a light pre-load
• Load evenly applied around bearing outer ring

Very high energy storage capabilities are an inherent design feature of these Disc Springs. This enables retention of required joint loads when used singly in high tensile bolted or other fastened joints. Other applications such as bus bar connections will require stacks of springs where high load or elimination of thermal effects and creep of materials are of particular importance.

To complement our extensive ranges of disc springs, we can offer the engineer a range of bowed or waved spring washers which will provide lower forces. These products can be offered with a wide range of surface coatings including phosphate and zinc passivated. All popular sizes are in stock and samples can be supplied on request. Our Technical Department is always available to resolve your specific application requirements.