It is the key to ensure life service of roller press by overlaying and maintenance timely to roller surface. The manufacturing and overlaying remanufacturing process requirements for squeeze roller include that there should be no crack in welding process, the hardness of roller surface is no less than HRC55, roller press works properly , abrasion resistance of roller surface and integration should be good and roller press are worn evenly in operation.

For normal wear, excessive wear, peeling off in large areas, overload operation, and other different failure modes caused by poor performance of roller itself and foreign material introduced to roller, usually three remanufacturing processes can be applied including on-line partial repair welding, on-line overlaying, off-line overhaul repair according to customers’ particular circumstances (Whether spare squeeze roller of roller press is available and repair is needed.),. On-line partial welding will be introduced as following.

Squeeze roller is big in size and weight. For example, the weight of two squeeze rollers of a TRP1400mm×1400mm roller press amount to more than 40 tons. It’s very inconvenient to dismantle and transport the rollers. Besides, there are no spare parts in some factories. So there are large amount of markets in demand for on-line overlaying squeeze roller.

Compared with off-line overlaying, onsite thermal treatment and machining are not available to on-line overlaying. It’s hard to guarantee the roller quality and service life after overlaying. Therefore, overlaying providers have to concentrate their efforts on materials and processes to achieve the same effects with off-line overlaying.

Without dismantling roller of roller press, for on-line overlaying, fatigue layer and abrasion destruction layer must be thoroughly removed, then auto or semi-auto process are used to overlay roller surface.

On-line overlaying process is much simpler. There is no overall preheating condition; hence fatigue stress cannot be eliminated. It’s only suitable for emergent repair. The service life of roller by on-line overlaying is shorter than that by off-line overlaying. The common schemes of on-line overlaying include:

① For the roller surface on which wear occurs only in hardfacing layer and there is no peeling off, if the quality of roller surface is better and there is no cavity, onsite overlaying can be applied in order to reduce costs:

a. Remove dust or other impurities of roller surface;

b. Fill and level up the depression area of the roller by repair welding with bottom layer wire;

c. Continuously weld wear-resisting embossment with hardfacing wire.

② For the roller surface of which there are severe peeling off and deep crack, if overlaying is conducted directly, it’s hard to avoid peeling off once again due to weak welding basis. In order to solve abrasion and peeling off problems of the roller, on-line overhaul can be applied and the process is shown as below:

a. Inspection. Inspection is needed for roller surface. For the removed roller material should be as little as possible. Firstly, remove the first layer with about 5-8mm by gouging. If there are still cracks, then remove the second layer, and so forth. Usually, if crack depth is less than 20mm, the whole layer where crack exists can be removed entirety. If crack depth is greater than 20mm, partial material of roller should be removed in circle. The difference between long axis and minor axis is no more than 2mm.

b. clean of roller surface. Thoroughly clear up the roller surface such as the dust, rust, hardened layer and even crack. The pre-welding work is completed after the roller surface is cleared up and there is no visible defect and the surface can be filed with file.

c. Welding wire of bottom layer is used for back welding to make rugged roller surface smooth, so as to weld transition layer and hardfacing layer.

d. Overlay transition layer and hard-facing layer successively.

e. Overlaying wear-resisting emboss layer by use of emboss layer wire.