Hidden Hazards Brought by Residual Stress Inside Roller Shells

During the casting, cooling, machining and heat treatment of roller shells for double roll crushers, internal residual stress will remain due to uneven casting thickness, differences in cooling rates and deviations in process control. Hidden inside the roller shell matrix without visible surface defects, such stress serves as a core latent trigger for premature failure of roller shells and abnormal equipment operation in ore crushing, sand making and construction solid waste crushing scenarios. It is easily overlooked during troubleshooting at most operation sites.

Residual stress in roller shells falls mainly into tensile stress and compressive stress, among which concentrated internal tensile stress poses the most prominent risks. Under alternating working conditions including no-load start-stop and continuous heavy-duty crushing, residual stress will superpose with working stress generated by material extrusion and continuously impact the metallographic structure of the roller shell matrix. Even if hardness and dimension parameters of roller shells meet standards during factory inspection, tiny internal metallographic defects will keep expanding after being put into actual production, gradually forming microcracks. As operation time accumulates, cracks extend slowly and eventually lead to unanticipated surface spalling and local peeling, shortening the service life of roller shells.

Unbalanced distribution of residual stress also undermines the overall structural stability of roller shells and triggers linked equipment failures. Stress-concentrated areas cause uneven local stress on roller shells, resulting in slight deformation during operation. This reduces the fitting degree between roller shells and roll hubs and creates tiny gaps. Continuous minor vibration will be induced during equipment operation, and vibration loads transfer progressively to supporting parts such as bearings, reducers and racks, aggravating wear of matching components, increasing the frequency of routine equipment maintenance and indirectly raising operation and maintenance costs of production lines.

In crushing conditions with alternating dry and wet environments or large temperature differences, negative impacts of residual stress are further amplified. The roller shell heats up due to friction during operation and cools rapidly after shutdown. Repeated thermal cycles cause continuous redistribution and cumulative superposition of internal residual stress, generating thermal fatigue damage. With long-term effects, the roller shell’s resistance to impact and deformation keeps declining. When impacted by high-hardness ore and bulk solid waste materials, its fault tolerance drops greatly and the probability of sudden failures rises notably.

Most buyers only focus on explicit parameters such as material, hardness and thickness when purchasing roller shells, while ignoring process control standards for residual stress. This explains why roller shells of the same material have big differences in service life at different sites. To avoid such latent failures, control should be implemented at the source of production processes. Precise heat treatment and aging treatment processes can release and balance internal residual stress of roller shells.

Hunan Xiangjian Machinery Technology Co., Ltd. specializes in mining wear-resistant parts. With mature casting and heat treatment processes, it precisely controls residual stress throughout roller shell production, adapting to various complex working conditions including ore crushing and solid waste treatment to reduce latent failure risks of roller shells from the source.

If your site encounters issues such as unexplained peeling of roller shells, frequent minor vibration of equipment or unsatisfactory service life, there is no need to blindly replace accessories. You can customize suitable roller shell process schemes combined with working conditions of production lines to resolve equipment hazards caused by residual stress fundamentally.