Under normal condition, the running time of squeeze roller after overlaying should meet the following requirements:

For squeeze roller after on-line overlaying, lifetime ≥4,000 hours; for squeeze roller after off-line overlaying, lifetime ≥8,000 hours.

The problems to be noted when overlaying squeeze roller are as follows:

(1) Although less time is needed and the total costs are low for on-line overlaying, there is very high welding stress in the roller since there is no heat treatment measure to eliminate welding stress. Besides, it’s hard to remove the fatigue layer of roller surface thoroughly onsite. Therefore, after 3-5 on-line overlaying operations, the degree of fatigue will be very high. If thorough heat treatment is not handled, the recycling service of roller will be shortened.

(2) When repairing partially or entirely, departure from roundness of the roller and diameter tolerance between two rollers should not be too big, or it may cause horizontal vibration of roller press and overload because of uneven size of two squeeze roller.

(3) Under long-term heavily stressed alternating load, the crack in internal weak parts of roller parent materials will also occur and develop due to fatigue rupture, thus there will be cracking in depth and peeling off and even breakage of roller. If original flaws exist in the internal of roller’s parent material, such as pinholes, composition segregation, bulky crystalline grain, blowhole, etc. the risk of fatigue rupture in roller’s parent materials will be increased greatly. Therefore, manufacturing quality of the parent roller should be strictly controlled to ensure the operation safety of roller press and its service life.

(4) It’s improper to weld immediately after abrasion on roller surface occurs. The thickness of hardfacing layer is usually about 10mm, while wear-resisting emboss layer is usually about 5mm. If the roller is overlaid once again when there is still emboss layer, the original wearing layer will be destructed and more crack will appear. Thus, the hardfacing layer will prone to peel off during operation. Therefore, it’s better to weld only after the whole wear-resisting emboss layer is worn out.