Adaptation of Fracture Mechanics Methods for Quality Assessment of Tungsten Carbide Cutting Inserts

Abstract

Tungsten carbide (WC) is well known as one of the hardest materials widely used in machining, cutting and drilling, especially for cutting tools production. Knowing fracture toughness grants the opportunity to prevent catastrophic wear of a tool. Moreover, fracture toughness of WC-based materials may vary because of different material compositions, as well as a different way of production. Hence, each material should be treated individually. In this paper, SM25T (HW) tungsten carbide (HW—uncoated grade, TNMR 401060 SM25T, manufactured by Baildonit company, Katowice, Poland) was taken into consideration. Sintered carbides—designated as S—are designed to be applied for machining steel, cast steel and malleable cast iron. Fracture mechanics methods were adapted to make a quality assessment of WC cutting inserts. Both quasi-statical three-point bending tests, as well as Charpy dynamic impact tests, were performed to calculate static and dynamic fracture toughness (KIC and KID, respectively). In addition, a special emphasis was placed on the microscopic analysis of fracture surfaces after impact tests to discuss material irregularities, such as porosity, cracks and so-called “river patterns”. There is a lack of scientific works in this field of study. However, cutting engineers are interested in obtaining the experimental results of that kind. Although there are a few standardized methods that may be used to determine fracture toughness of hard metals, none of them is expected to be the most reliable. Moreover, there is a lack of scientific works in the field of determining static and dynamic fracture toughness of WC by the presented method. The proposed examination solution can be then successfully used to calculate toughness properties of WC-based materials, as the results obtained seem to be with a good agreement with other works.

Effect of Laser Heating on the Life of Cutting Tools Coated with Single- and Multilayer Coatings Containing a TiN Layer

“…After heating with 40% of the maximum laser power, their color changed to golden, whereas, after heating with 50% of the maximum laser power, the color became darker (golden brown). The color changes observed for the TiN coatings were confirmed by chemical microanalysis results [ 6 , 46 , 47 , 48 , 49 ]. Figure 19 shows images of the surface of the test samples before (a) and after laser heating with (b) 40% and (c) 50% of the maximum laser power.…”

Finite Element Analysis and Experimental Investigation of Cut Surface Formation of Magnetic Silicon Steel in Shear Cutting

“…Maps and photographs are made using confocal microscope LEXT OLS4000. On cut surface in macro and micro scales irregularities (asperities) can be seen in which heights and alignment can affect the tribological properties of steel after the cutting process [25,26]. The quality of the burnished area can have a significant impact on the operational properties of machine components trough the friction conditions in the contact areas, the contact stresses, fatigue strength, joint tightness and magnetic properties.…”

Analysis of Geometric Surface Structure and Surface Layer Microhardness of Ti6Al4V Titanium Alloy after Vibratory Shot Peening

“…Catastrophic tool wear is particularly dangerous in the cutting process. Understanding the mechanics of fracture in carbide cutting inserts can help prevent this phenomenon [13]. Titanium has a relatively low longitudinal elastic modulus, making it susceptible to deformation during machining.…”