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Regeneration of raceways


Main components of a rotary drum are rings and rollers, which are forming its support system.
The drum's working movement is rotation, additionally accompanied by axial displacements. Resistance of both movements is closely dependent on the contact conditions between the surfaces of rollers and rings. Correct contact between the two is guaranteed only when the raceways of both components are cylindrical in shape.
Unfortunately, even during normal operation, rotary drum is exposed to numerous factors, which in a long run will cause deformation of the contact surfaces, making the rolling components loosing their original shape in a larger or smaller degree. Such factors are:
  • roller shafts misalignment /1/,
  • ring axial run-out /2/,
They result in excessive and unevenly distributed loads on the contact surfaces of the ring and the rollers.
Complete elimination of the above-mentioned factors is difficult, and sometimes even impossible. Shape errors (/3/, /4/) are therefore inevitable, and their magnitude and rate of occurrence depends on the number and values of faults.
Errors, even the smallest, disturb the correct distribution of forces in the rotary drum's support system, forming points where the unit loads exceed the permissible values /5/.
In extreme cases such errors can cause serious disturbances in the drum's movements, both rotary and axial.
Movement resistance and incorrect distribution of forces can result in considerable damage, such as:
  • wear, breaks of the thrust stop blocks /6/,
  • bearing bushing damage by excessive loads /7/,
  • breaks of the roller shafts' thrust collars,
  • hastened wear of the rollers and rings raceways caused by increased unit loads in their contact areas /8/, /9/.
Such a movement resistance has also a negative effect on the drive system, where the teeth wear in the gear unit is following faster /10/. This creates a feedback which results in further deformation of the rings raceways, this time as characteristic furrows /11/.
Removal of such a damage entails significant costs caused by both, production downtime and elimination process of the failure results.


Other important elements of rotary kiln support system are the thrust rollers. By taking part of the axial forces acting on the object's support system, they are often exposed to considerable loads. For this reason, it is very important to ensure the proper roller's positioning and raceway contact with the front surface of the live ring, so the forces distribution will be even and there will not be any formation of excessive stresses or vertical forces - over pressing or picking-up the thrust roller on the frame. What in extreme case may lead to total failure of roller structure or damages of live rings' suspension system.
Periodical checks and restoration of the correct shape of live rings and support and thrust rollers raceways is desirable from the technical point of view and fully justified business-wise.


The shape can be restored in a traditional way: by dismantling and machining on stationary equipment. In such case, the downtime is inevitable: if the rollers are refurbished, the downtime will be shorter (a few dozens of hours); in case of the ring, the downtime will be fairly longer (several weeks).
The costs of restoration are also sizeable, and include amongst others:
  • dismantling and re-assembly (in case of the ring, often the kiln's shell needs to be cut),
  • transport (difficult, as the parts are usually oversize),
  • machining (machine tools are few and expensive).
Machining without dismantling any parts of the facility, even during its normal operation can significantly reduce such costs.
In case of the support and thrust roller, which axis of rotation is relatively stable, for turning and grinding operations we can use more or less adapted traditional machines.
In case of rings raceway, continuous changing of the axis position, necessitates much more sophisticated and refined technology, unavailable on a day-to-day basis.
The machining requires also a deep knowledge and an extensive experience in measurements and adjusting of such facilities.


The knowledge and experience which dispose ZMP engineers, together with the state of the art equipment, allow effectively resurface rollers and rings raceways without the necessity of their dismantling.
Appearing always in case of the ring and sporadically in case of the support roller, displacements of the rotary axis of the machined element, are compensated by the rotary joints which allow machine to follow-up to the right position.
Constance of the diameter is assured by the proper design of the rolling guiding system. The idea of the solution is basing on the three points determination of the circle diameter. Constant holding down is provided by the pneumatic cylinder. Thanks to that machining parameters are constant what is very important for the obtaining good quality surface after grinding.


Having in our disposal so specialized machines supported by our engineering knowledge of rotary drums related problems, we can offer you a complex service of support, thrust rollers and live rings raceways resurfacing.
The service contains:
  • qualifying analysis, to determine advisability and possibility of resurfacing service;
  • measurement and engineering assistance over the support roller’s position adjustment;
  • resurfacing of the roller /12/ / ring raceway /13/ with control of the diameter and shape of the generating line of the grinded element;
  • resurfacing of the thrust roller - restoration of the initial generating line shape /14/;
  • resurfacing of live ring’s front surface – in contact with thrust roller - restoration of the outline and/or cone’s angle /15/.


  • no need for costly and time-consuming dismantling and re-assembly;
  • elimination of expensive transport to and from the machining facility;
  • minimizing the production losses (only in extreme situations resurfacing could disturb production process - necessity to decrease rotation speed of the drum in case of high vibration level of resurfacing elements);
  • during machining, the reference line is actual axis of rotation of the piece (high accuracy, minimal shape errors);
  • low surface roughness after regeneration.


  • grinding of the raceways of support rollers, live rings (tires) – rolling raceways and front surfaces and thrust rollers of rotary drums without dismantling;
  • grinding of other large rotary pieces, without dismantling (indispensable rotation of the resurfacing element).

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