• caliber gauge
  • caliber
  • calibrating
  • measuring wire

A caliber is a measuring instrument used as a gauge. In steel mills, gauges are used to determine the rolling gap. On straightening units, calibers are used to fix the distance between the straightening rolls.

When a caliber is placed between the open straightening rolls of a straightener, all the adjustable straightening rolls can be aligned on one line. The straightening rolls of the one row are thus parallel to the straightening rolls of the second row. It is then possible to set the zero line for the particular product to be straightened. The adjustable rolls are adjusted by an amount equal to the difference between the thickness of the caliber and the thickness of the product to be straightened. It should be note that the adjusting travel is also affected by the geometry of the product to be straightened and the geometry of the groove. Adjustment positions are reproducible at any time.

Carbon content

  • alloy component
  • carbon content
  • image of microstructure
  • steel wire

The carbon content of a steel wire is crucial for many of its properties. The higher the carbon content, the greater the tensile strength but the smaller the elongation to fracture. Wire with a very low carbon content is referred to as iron wire. Its tensile strength is low. Wire made of spring steel generally has a high carbon content of between 0.4 and 1.0%, resulting in high tensile strength values.


  • cassette technique
  • cassettes
  • relubricating
  • seal
  • straightening roll


The rolling elements mainly used in straightening processes with roll-type straighteners suffer extreme wear as the result of the high roll adjusting forces and ever higher production speeds. At the same time, metal particles contaminate the bearings and contribute likewise to a drastic shortening of rolling element life. The WITELS Cassette Straightening System called WICAS(r) was developed specifically to improve this situation.

Notable features of WICAS®:

A) Expert installation of the rolling elements in a closed housing with an additional labyrinth seal prevents practically all soiling of the bearing system, resulting in a useful life up to 30 times longer than that of a conventional straightening roll.

B) The straightening sheave can now be produced in any form, type, quality and strength irrespective of the material used for the bearing system. Oval pressing of the rolling element outer ring, against which the product to be straightened runs, is ruled out with this design.

C) The use of smaller rolling bearings at high speeds of rotation increases the peripheral speed of the larger straightening sheave. Far higher production speeds are thus possible than with conventional straightening rolls.

D) In the case of miniature straightening rolls, cutting the groove in the relatively thin outer rings weakens the straightening roll to an unacceptable degree. This does not happen with WICAS(r) because the bearing shaft as well as the straightening sheave can be made with annular grooves of any shape and size.

E) Flexible use of needle and ball bearings gives the designer considerable scope with regards to the static and dynamic bearing values.

F) It is possible to use bearings with life-time lubrication as well as systems designed for relubrication.

The above-mentioned 30-fold longer useful life of WICAS(r) compared to conventional straightening rolls greatly minimizes the cost-intensive stoppage of individual machines and complete production lines - a benefit that should not be overlooked. 

Causes of stress

  • bending stress
  • internal stresses
  • origin of stress
  • stress analysis
  • tensile stress
  • torsional stress

Stress is the reaction of a material/workpiece to an external load. It is defined as an internal force of resistance per unit of area. There is a fundamental correlation between the condition of stress and the condition of deformation of a workpiece. A plastic deformation produces internal stresses in a workpiece which remain after the load is removed. Stresses arising during loading of such a plastically deformed workpiece are superimposed on these internal stresses. The type of stress produced during loading is characterized by the type of load. Tensile forces (drawing, coiling) result in tensile stresses while bending forces (deflecting, straightening) result in bending stresses.


  • Coil
  • wire coil
  • wire ring

For logistical reasons, products to be straightened (wire, strip, rope, etc.) are wound into coils. This entails laying the product, winding for winding, in the direction of the coil axis. If the coil is not rotated simultaneously during the laying, helicities will be produced with each winding. The product will then behave accordingly when it is pulled off. Pulling off the product statically in the direction of the coil axis will cause it to twist and the quality of the straightened product will be negatively affected by additional helicities. These curvature fluctuations and helicities are difficult to eliminate and are therefore best avoided in the first place.

The beginning and end of a coil should always be marked in order to ensure its careful and correct further processing. Constriction-free securing of the ends prevents snap-back and avoids kinks.


  • braking
  • coiler
  • decoiling
  • pay-off
  • reeling
  • unwinding technique
  • wire coiler

A coiler is a device for the winding or unwinding of a lengthy process material.

In direct or indirect interaction with other components it is also used to create tensile stress.

Important technological sub-functions such as guiding the process material are likewise performed by a coiler.


  • coil curvature
  • coil winding
  • deviation from the straight
  • deviation
  • free wire bypass
  • spool curvature
  • winding
  • wire bend
  • wire curvature

Curvature is understood to be a deviation from the straight.

When an endless material is wound onto a spool, the inner layers have a smaller radius of curvature and the outer layers a larger radius of curvature.

Whether or not a winding is elastic or plastic depends on the spool geometry, the properties of the endless material, and the degree of deformation.

Curvature is the reciprocal of the radius of curvature and has the dimension [1/mm].

Curvature course during straightening

  • adjustment induced curvature
  • bend
  • bending up
  • change of direction
  • counter-bending
  • counter-curvature
  • curvature course during straightening
  • opposite direction
  • reduction of curvature
  • straightening triangle

The curvature course during straightening is understood to be the correct sequence of curvatures followed by the process material during the straightening process.

The initial curvature is always followed by the counter-curvature. The final curvature is the curvature remaining after spring back. This curvature sequence is repeated according to the number of straightening rolls.

A straightening process should be arranged so that, irrespective of the initial curvature, the last adjustment-induced curvature resulting after the last spring back in a final curvature corresponds to the desired straightening result.