A Fuzzy Evaluation of Tool Materials in the Turning of Marine Steels

To recommend one suitable tool material for the cutting of marine steels under special conditions and requirements in emergency rescues of capsized steel ships, the cermet tools, cemented carbide tools and coated carbide tools were evaluated using a fuzzy evaluation method concerning cutting force, cutting temperature, surface roughness and tool wear. Experimental results indicate that the tool cutting performance was diverse and difficult to evaluate with a single evaluation index. The cemented carbide tools presented bad cutting performance with severe wear. Compared with the cemented carbide tools, the cermet tools showed excellent wear resistance with about 60.3% smaller tool flank wear value and good surface quality with about 46.8% smaller surface roughness. The coated carbide tools presented low cutting temperatures about 15.6% smaller than those of the cermet tools. The result of fuzzy evaluation demonstrates that the cermet tools presented the best cutting performance, followed by the coated carbide tools, and then the cemented carbide tools. The cermet tools are recommended to cut marine steels in emergency rescues of capsized steel ships.

Analytical modeling of tool failure boundary map in milling titanium alloy

As a typical aerospace difficult-to-machine material, tool failure in milling titanium alloy Ti6Al4V will reduce the stability of the milling process and affect the surface quality of the workpiece. Aiming at the fact that cemented carbide tools are prone to wear failure and breakage failure in milling titanium alloy, a safe tool failure boundary map is provided to ensure that the tools will not occur failure with the cutting parameters selected in the safe area during the prediction time. Based on the processing characteristics of Ti6Al4V, the failure boundary map mainly considers three forms of tool failure: flank wear, rake wear, and cutting edge breakage. By revealing the three failure mechanisms, the failure analytical model is established and the failure boundary map is obtained. Compared with the experimental results, it has good consistency, and the research results can provide a reference for the field of titanium alloy cutting process.

Study of the Processing of a Recycled WC–Co Powder: Can It Compete with Conventional WC–Co Powders?

Cemented carbide tools suffer from many issues due to the use of tungsten and cobalt as raw materials. Indeed, those are listed by the European Commission as “critical raw materials” since 2011 and by the US Department of Interior as “critical minerals” in 2018. To remain competitive with the conventional high-speed steels, less performant but cheaper, WC–Co tools can be recycled. In the present paper, a WC–7.5Co powder, recycled by the “Coldstream” process, has been sintered with vacuum sintering. As preliminary experiments have shown that the sinterability of the powder is low, the sintering temperature was set at 1500 °C to achieve full density. In parallel, the influence of ball milling conditions (rotation speed and milling medium) on the reactivity of the recycled powder has been studied in terms of grain size distribution, hardness, and fracture toughness. The optimized milling conditions were found to be 6 h wet milling, leading to a hardness of about 1870 HV30 and a toughness of about 10.5 MPa√m after densification. The recycled powder can thus totally compete with conventional powders, opening avenues for the recycling of cemented carbide tools. Graphical Abstract