Whether it is possible to repair rims?Repair of light-alloy wheels, unfortunately, still very widespread phenomenon in many countries. I would like to explain the reasons, from - for whom it is necessary to avoid such repair.
The websites of specialists in repair of rims give such information:
1) the damaged disks are exposed to heating and the subsequent skate
2) process of editing of a disk provides that uniformity of strength characteristics of various sites of a disk will be within the admission
3) the material applied at repair of the damaged disk sites is identical to material of which the disk
is made Further I will disprove these theses and for a start I will cite the information leaf published in March, 1999. The German Association of Sellers Shin and the Organizations for Repair of tires (Bundesverband Reifenhandel und Vulkaniseur - Handwerk e. V.) .
Was considered a case of repair of a disk with strongly crumpled rim (but without formation of cracks) in the repair shop specializing on “ treatment of the disks “.
After the made repair a rim was surveyed and the following results are received:
“ 1) machining of the shelf of a rim led to violation of admissions on geometrical indicators (in particular: length of a circle of the shelf, length of a circle of a hamp, radius of curvature of a zakraina of a rim and external diameter) of
2) at the same level of loading, local heating and deformation reduced energy of absorption approximately by 25%.
leads such change in characteristics of material to the fact that material begins to accumulate deformations * (from driving on obstacles or on uneven surfaces of a roadbed - crossing of railway crossings, cross furrows and so forth)
From our point of view, we oppose such repairs. “
Source: BRV (German Association of Sellers Shin and Organizations for Repair of tires), article: “ Repair of disks from " aluminum;.
* - a comment of the translator: accumulation of residual deformations in other words means changes in a crystal lattice of an alloy. As a result material with such saved-up deformations can collapse even at the appendix of small loading. Behavior / life cycle of a detail from such material is unpredictable.
On the website of authoritative noncommercial Association of the European Producers of Rims (EUWA) www. euwa. org uniting a number of the largest global manufacturers of disks you can learn why this association also strictly forbids to carry out repair of light-alloy wheels. In the statements concerning safety of use of rims, EUWA specifies the following:
“ Repair of the damaged disks regarding a rim or the central part by heating, welding, addition or removal of part of material of a disk we do not accept at all. Repair results in concentration of loadings in already critical areas of a disk. “
Answers to a question why cannot be heated, welded, added material or to remove it it is possible to receive from the chart of static stretching of metals (dependence of deformation of ε metal; from action of tension σ) .
To a proportionality limit (here - ReH point) material changes elastically on Hooke`s law, material after loading reverts to the original state. At bigger loading accumulation of residual deformations begins. Outside elasticity and fluidity it is not possible to return properties of material. Process of deformation comes to the end with destruction.
the Basic conclusion - the deformed material of a disk is not subject to restoration.
Annealing and recrystallization of a site of a disk are not possible, and heating of part of a disk (for example when welding) also leads to accumulation of residual deformations in material.
Concerning the analysis of material of which the rim is made: the authentic analysis within repair shop cannot be carried out because from - for difficult modern processes of production (for example: molding under low pressure, the special modes of cooling, heat treatment) not all metallurgical institutes can brag of the fact that on samples they will specify reliable initial structure of an alloy. to
Besides, for receiving reliable information about structure of an alloy it is necessary to take material samples from several sites of a disk (and it will lead to final fracture of a disk).
Even if production of part of a disk with the same composition of material, as a disk would be possible, its joining with a disk by method of welding would cause changes in structure of the repaired part of a disk (for the reasons described in the previous paragraphs).
As the conclusion.
Any intervention in rim material (heating, welding, peening, machining, etching, etc.) lead anyway to change of mechanical properties.
Note motorists: neither action of certificates, nor guarantees extend to such disk.
So-called “ repaired “ the light-alloy wheel can be threat for your life as its destruction is unpredictable.