## 2 Theoretical Basis  
### Abrasive Belt Grinding Process  
Abrasive Belt Grinding is a tertiary polishing process with a geometrically indeterminate machining edge with multiple grains. The belt grinding setup has an elastic contact roller wheel made up of thermosetting polyurethane elastomer, which can be deformed to assist the coated abrasive belt that functions as the cutting edge, as illustrated in Figure 1. Compliant belt grinding corresponds to elastic grinding and has the capabilities of grinding, milling, and polishing [15]. The belt grinding process has characteristics of good workpiece-shape adaptability with uniform material removal, low grinding temperature, maintenance of residual compressive stresses, and resistance to workpiece burning like any other tertiary finishing process. The belt grinding process can quickly generate surfaces with high levels of precision and smoothness. Presently, about one-third of abrasive wheel grinding has been substituted by belt grinding [15]. Similar to any other abrasive machining process, many process parameters in belt grinding impact the last ground surface quality, including the grinding belt topography features and cutting parameters. The process parameters include belt speed, belt preloaded tension, the force imparted, feed rate, workpiece geometry, polymer hardness, and belt topography features such as grit size [3]. [PERSON] [5] had proposed a linear mathematical model as shown below as Equation (1), which states that the overall material removal rate (MRR) \(r\) is either relative or inversely proportional to parameters such as \(C_{A}\) (constant of the grinding process), \(K_{A}\) (combination constant of resistance factor of the work coupon and grinding ability factor of the belt), \(k_{t}\) (belt wear factor), \(V_{b}\) (grinding rate), \(V_{w}\) (feed-in rate), \(L_{w}\) (machining width), and \(F_{A}\) (normal force). \[r=C_{A}.K_{A}.k_{t}.\frac{V_{b}}{V_{w}.L_{w}}.F_{A} \tag{1}\]  
The material removal intensifies when the number of the interactions of the abrasive grains per unit time gets maximised [16]. Therefore it is evident that material removal is directly proportional to the cutting speed (grinding rate) of the polymer contact wheel on the belt grinder. The depth of penetration depends on the topography and the geometry of the belt/wheel surfaces, which serves as an undefined cutting-edge. The coarser grain sizes exhibit a greater ability to achieve higher cutting depth, which results in higher material removal than finer sizes. Material removal increases with a higher dwell time of interaction between the cutting grain edges, and workpiece surface, i.e., material removal, is inversely proportional to the feed-in rate [16]. Adequate force is required for the cutting edge to penetrate deeply into the workpiece to achieve grain cutting depth resulting in material removal. The penetration depth of the grains into the work coupon surface predominantly depends on the force imparted for grinding [16]. Belt finishing with contact wheels of different hardnesses results in dynamic changes in contact pressure, leading to a change in the mechanism of wear. This hints that the parameters discussed govern the belt grinding process, and changing any of the parameters will have a resultant shift in the output. Stock removal commonly requires a harder polymer contact wheel, coarse abrasive grains, greater force, reduced feed, and better cutting speed. Finishing requires the use of a softer contact wheel and fine grade abrasive grains. However, the degree of the effect will vary parameter to parameter. The amount of material removed from the workpiece surface results from the distinct local contact conditions, which are completely influenced by the process parameters/variables. The relationship between the material removal rate and process parameters is not well grasped, even though machining by belt grinding is remarkably straightforward and inexpensive.