Experimental study of the diamond turning characteristics of tungsten carbide (Co 0.5%) when using a chamfered diamond bite

Recent Progress in Precision Machining and Surface Finishing of Tungsten Carbide Hard Composite Coatings

“…Diamond turning machines make use of cutting-edge control systems and technologies including vibration isolators, air spindles, precision hydrostatic sliders and bearings (Figure 8), which provide rotational accuracy and allow accurate control of the relative motion between the diamond tool and the workpiece [62,63]. It is a preferred technique over other methods such as grinding and polishing, as it provides a higher material removal rate and higher flexibility, due to multi-axis control systems [15]. Such flexibility makes the machining of complex geometries possible, and is widely used in the machining of spheres and unsymmetrical shapes [64].…”

“…Tool wear depends on the properties of the material being machined and has a great bearing on the workpiece resultant surface finish. During machining of hard coatings, alternating stresses are involved between the cutting tool and the workpiece manifested, as high cutting forces and high temperatures [15]. Combined with a hard workpiece, such conditions may lead to premature wear of the tool resulting Despite providing smooth surface finish and optimal tolerances, a number of critical factors are associated with the process which require serious considerations prior to undertaking a machining process.…”

“…Subsequently, as machining progresses, the uncut portion is removed by the adjacent cutting edge to form another wear zone. Significant improvements to eliminate such occurrences were reported when using a chamfered bite rather than a conventional bite [15]. An additional problem associated with the processing of WC-Co coatings using diamond tools is diamond graphitisation as cobalt is a catalyst of diamond graphitisation causing an increase in the tool wear [72].…”

“…As outlined, theoretically, diamond turning of tungsten would be difficult to achieve due to its high wear impact on diamond tools. Based on findings in literature some attempts have been made to explore the possibility of diamond turning WC-based coatings [15,66,73,78,79], but not enough information is available to extract proper operational parameters which could confidently be relied-on. Based on these considerations, turning of binderless WC/W coatings would be possible but it would highly depend on the coating's level of hardness.…”

“…The key driver can be attributed to the tight restriction on the use of hexavalent chromium, which is the main component in plating of hard and decorative chromium coatings, under environmental and health and safety regulations due to its severe adverse health effects [10,11]. Whilst significant developments have been made within the last decades on understanding of machining and finishing techniques and mechanisms of WC coatings [12][13][14][15], these studies focus on cemented carbide coatings. Note that cemented carbide coatings comprise of hard WC grains embedded within soft metal binder matrices, such as cobalt, iron or nickel, and are commonly deposited through a line-of-sight vapor or liquid electrochemical process [16,17].…”