Rolling and Sliding

For many centuries the application of materials for low friction and wear in sliding and rolling contacts primarily involved wood, stone, leather, iron, and copper. Almost all engineering materials have since been employed at one time or another in the continuing search for the best bearing material. Final selection is commonly a judgment based on the most essential material properties, ease of appHcation, and cost. 

Friction is defined as the resistance encountered when one body moves tangentially over another and they are in contact. Friction often embraces two classes of relative motion sliding and rolling. In industrial processes, frictional energy is usually dissipated as waste heat. The friction force is represented by F and the friction coefficient by p. Under many sliding conditions, the p for a given pair of materials and fixed conditions of lubrication is mostly constant. The three laws of friction are ... 

Production of the WG can be accomplished by several methods. Among the oldest is pan granulation. The powdered formulation is slowly fed onto a slanted rotating pan, and the binder solution is sprayed onto the powder as it slides and rolls around on the rotating pan. Granules are formed, and their size increases. The manufacture of acceptable granules depends on many variables, and this process is very much an art [27]. 

M.B. Peterson and J.F. Murray, Requirements of Materials for Sliding and Rolling Contacts, Boundary Lubrication, American Society of Mechanical Engineers, 1969, Chapter 9. 

Solid Friction. Solid friction occurs when there is physical contact between two sohd bodies moving relative to each other. The type of motion divides solid friction into two categories, sliding and rolling friction. 

With gears, both sliding and rolling conditions exist as the gears mesh and unmesh. They are grouped according to their contact area and action. 

It is doubtful whether it can be correlated to dynamic friction (sliding and rolling) applications. 

Buldum, A. and Lu, J. P., Atomic scale sliding and rolling of carbon nanombes. Physical Review Letters, 83 (24), 1999,5050-5053. 

Sliding Bed Flow This mode of flow is generally nnsatisfactory. Solids slide and roll on the pipe bottom. Excessive corrosion in the pipe bottom occurs quickly. Blockages can occur frequently... 

However, Cameron [7] had already indicated that the existence of lubricated film even under opposite sliding and rolling conditions i.e. in zero entrainment velocity, which has not been hardly known until recent years in spite of discovery about SO years ago. He carried out an experiment with two disks of bronze and steel and measured traction and electrical resistance between the disk surfaces. The eiqierimental results indicated the resistance increased and the traction decreased as well as scuffing did not occur with increasing the sliding speed. Cameron supposed the film formation would be caused by the temperature difference of the bounding surfaces at both the inlet zone and called... 

Experiments were carried out in two basic conditions. One condition was sapphire-steel contacts with a paraffinic oil (PlOO) to investigate characteristics of the film formation in the opposite sliding and rolling conditions. The other condition was CaFa-steel contacts with an aromatic traction oil (SantotractOO) to investigate the mechanism of the dimple occurrence in the Kaneta s conditions. The properties of the oils are shown in Table 2. The experiments were carried out at room temperature of 23 1.0°C. 

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