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Mastering and controlling movement

Precision springs

Springs in general (coiled)

Springs are standard parts. They are cold- or hot-formed from alloyed or unalloyed spring steels with round, square or rectangular cross-sections. Coiled springs are normally manufactured from spring steel wire in accordance with EN 10270-1. Both conventional tension and compression springs and single-start machined springs consist of a spiral with a beginning and an end.

With such a (single-start) spring, the force is only applied via a single point and causes a tilting moment – the distance between the longitudinal axis of the spring and the center line of the spiral acts as a lever arm. This means that long helical compression springs can buckle under load. This so-called buckling is dangerous, as the spring no longer transmits its force but simply fails.

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In order to avoid such lateral movement or curvature, conventional single-start springs above a certain length must be guided on a mandrel or in a sleeve, which in turn creates undesirable friction and affects service life and functionality. In addition, lubrication is required – which may not be desirable depending on how the spring is used.

Customized u-Flex precision springs

However, this is different with precision springs from u-Flex – we manufacture cutting springs from a single piece. Like coiled springs, these springs can be subjected to compressive, tensile and torsional forces as well as bending stresses. The big difference to conventional springs, however, is that these springs allow an optimally coordinated combination of different spring values. In the case of multi-start springs, the compression or tension is also distributed over several points, resulting in a uniform parallel force distribution to the central axis. The more coils a spring has, the more precisely the parallelism is implemented during compression or extension.

A major advantage of this spring shape over conventionally coiled springs: Very precise and constant spring rates of up to ± 0.1 % can be achieved with a repeatability of up to 1 %.

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Manufacture

Precision springs are produced from solid material, e.g. from a rod or tube into which a helical groove is cut. In contrast to forming or coiling, this machining manufacturing process for precision springs does not generate any internal tension that has to be overcome to apply the force, but only a natural material tension. During loading, all spring coils are active. The spring deforms evenly and returns to its original shape when the load is released. This gives the spring a linear spring characteristic curve with high repeat accuracy and fatigue strength.

u-Flex

Our know-how - your benefits

Chip-removing precision springs from u-Flex offer a wide variety of design options as well as maximum precision and functional reliability, as only one single component is required for the main function, the compression spring. This minimizes both procurement and storage costs.

Integrated functions - reduction of components

Customers who rely on our expertise and experience benefit from several advantages. We offer a wide range of options in terms of fastening and spring connections as well as the integration of various functions. This increases both the service life and the safety of the components. At the same time, the overall costs resulting from unit costs and procurement, among other things, can be optimized.

Reduction in total costs

You need fewer components for a function - this means shorter assembly/installation times and minimized procurement costs.

High Security

A single component means clear interfaces. We are also your contact for several functions. This in turn means: high system reliability with a high quality standard in one component.

Low storage and administration costs

Thanks to u-Flex's one-piece connection, customers need fewer components in stock. This reduces the number of orders and suppliers.

Reduced development effort

On request, we can create design proposals for our customers free of charge. You too can benefit from our expertise and our innovative calculation software.

Material

Conventional springs are made from alloyed or unalloyed spring steel wire. For the production of u-Flex precision springs, our customers can choose from a very wide range of materials. The elasticity or sliding modulus is decisive for the selection of the spring material. This material parameter describes the relationship between tension and elongation and should be as high as possible. Depending on the intended use, the following material properties are also decisive for springs:

  • Low relaxation – high permissible stresses even at elevated temperatures without major loss of force
  • High fatigue strength (fine-grained structure, free from impurities)
  • Surface as slippery as possible, e.g. through surface coating
  • Corrosion protection
  • High electrically conductive or antimagnetic properties
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Technical basics

Comparison of standard spring vs. precision spring

Standard spring

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Precision spring

Spring rate in the range of ± 5 % – customer-specific rates with a tolerance of ± 1 % or even up to ± 0.1 % possible

The right choice of fastening

Conventionally wound spiral springs

These are normally fastened with attached wire, ground ends, pins, rings or hooks made from the spring steel itself. It is precisely such small bending radii that cause excessive material stresses and are a frequent cause of (premature) failure of the component.

This is because these fixing points are not able to transfer the torques that occur within the spring under compressive, tensile or torsional stress to the adjacent components and bend under load.

The finite element method (FEM) provides precise information on displacement and torsional
torsional load as well as the strength and service life of specific applications
applications when one is on the edge of physical feasibility.

Guide values for the use of precision springs

Compression and tension springs

  • Compression or tension force from 2 to 4500 N
  • Outer diameter from 1.5 to 80 mm
  • Lengths from 6 to 500 mm

Torsion springs

  • Torsional moment from 5 to 225 Nm
  • Torsion angle from 1 to 360
    Outer diameter from 1.5 to 80 mm
  • Lengths from 6 to 500 mm

Springs produced by chip removal

These have connections that are reduced to the bare essentials and are reinforced where necessary. Unsupported moments are prevented, for example, by using double pins, cross slots, grooves, mounting flanges, etc.
Such integrated connections increase the service life of springs and the installation space can be optimized. Production and assembly costs can often be reduced at the same time.

u-Flex

More about our precision springs