A recent survey by OpenText found that 92% of manufacturers consider corporate social responsibility (CSR) to be important for their overall reputation in the markets. Although steel turning is, by nature, a waste-producing process, it is possible for manufacturers to improve their sustainability without compromising process security—even while facing the unprecedented challenges of COVID-19. Here Rolf Olofsson, Product Manager at Sandvik Coromant, the global leader in metal cutting, explains a different approach to steel turning.
According to the
17 Global Goals for Sustainable Development set out by the United Nations (UN), manufacturers are expected to minimize their environmental impact, going beyond just optimizing energy use. Although CSR is important to companies, Sandvik Coromant estimates that manufacturers waste between 10% to 30% of material in their machining processes, with a typical machining efficiency of below 50% across the design, planning and cutting phases.
So what can manufacturers do? The UN's goals recommend two main avenues that take into account such factors as a growing population, finite resources and the linear economy. The first is to address these challenges with technology. Industry 4.0 concepts such as cyber-physical systems, big data or the Internet of Things (IoT) are frequently cited as being the way forward for manufacturers seeking to reduce waste.
Yet this does not allow for the fact that most manufacturers have yet to apply modern machines with digital capabilities in their steel turning operations.
Most manufacturers are aware of how important the choice of insert grade is for making steel turning more efficient and productive, as well as how this affects overall performance and tool life. However, many are missing a trick by not considering the tooling concept as a whole—everything from advanced inserts and tool holders to easy-to-adopt digital solutions. Each of these factors can help to make steel turning more sustainable by reducing energy consumption and minimizing waste.
Reduced cutting speeds
Manufacturers face a number of challenges in their steel turning operations. These include getting more pieces per edge from a single insert, increasing metal removal rates, reducing cycle times, optimizing inventory levels and, of course, minimizing material waste.
What if there were a way to meet all these challenges while also aiming for overall greater sustainability? One way to reduce energy consumption is to reduce cutting speeds. Manufacturers can maintain productivity by proportionally increasing the feed rate and depth of cut. In addition to saving energy, this also results in longer tool life. In steel turning processes, Sandvik Coromant has found that an average tool life increase of 25%, in combination with reliable and predictable performance, can minimize material waste both from the workpiece and the insert.
The right choice of insert grade substantially contributes to achieving this. That's why Sandvik Coromant is adding a pair of new P-turning carbide grades, designated GC4415 and GC4425,
to its range. GC4425 delivers improved wear resistance, heat resistance and toughness, while grade GC4415 is designed to complement GC4425 when enhanced performance and more heat resistance are needed.
Importantly, both grades can be used with tough materials like Inconel and unalloyed stainless steel ISO-P grades, which are especially complex and tough to machine. The right grade can help machine a larger number of pieces within mass and/or batch production processes.
The GC4425 grade provides extremely high process security through its ability to retain an intact edge line. Because the insert can deliver more pieces per edge, less carbide is consumed to machine the same number of components. Furthermore, inserts with consistent and predictable performance avoid workpiece damage, minimizing workpiece material waste. Both advantages reduce the amount of scrap produced.
Additionally, with both GC4425 and GC4415, the insert's substrate and coating have been developed to better withstand high temperatures. This reduces the effect that causes excessive wear. As a result, the material excels at maintaining the insert edge line at higher temperatures.
However, manufacturers should also consider using coolant with the insert. When using a tool that features over and under coolant, turning off the over coolant can be beneficial in certain operations. The primary functions of cutting fluid are chip evacuation, cooling and lubrication between the tool and the workpiece material.
If applied correctly, it maximizes the output, increases process security and improves tool performance and component quality. Using tool holders with internal coolant provision can also improve insert tool life.
Peel back the layers
GC4425 and GC4415 each contain a layer of second-generation Inveio®, a textured chemical vapor deposition (CVD) alumina (Al2O3) coating developed for machining. Examining Inveio at the microscopic level reveals that the material's surface is characterized by unidirectional crystal orientation. Furthermore, the crystal orientation has been improved significantly in the second-generation Inveio coating. Even more so than before, each crystal in the alumina coating is lined up in the same direction, which creates a strong barrier towards the cutting zone.
Inveio provides inserts with high wear resistance and longer tool life. Longer-lasting tools are, of course, favorable for reducing cost per part. Moreover, the material's carbide substrate contains a high proportion of recycled carbide material, putting these among the most environment-friendly grades.
To test these claims, the GC4425 grade has been subjected to pre-market tests by Sandvik Coromant's customers. One of these was a general engineering company that applied both a competitor's insert and the GC4425 insert in the manufacture of pressure rollers. An ISO-P grade was subjected to continual external axial machining and semi-finishing at a cutting speed (vc) of 200 m/min, feed rate of 0.4 mm/rev (fn) and depth (ap) of 4 mm.
Manufacturers typically measure tool life by the number of workpieces machined (pcs). Whereas the competitor's grade machined 12 pieces before wearing out due to plastic deformation, Sandvik Coromant's insert produced 18 pieces and, in doing so, worked 50 percent longer with stable and predictable wear.
This example shows the potential gains when the right machining elements are brought together, and how recommendations for first-choice tools and cutting data from a trusted partner like Sandvik Coromant can help achieve process security and also reduce time wasted in finding the right tools. Online tools, such as the
CoroPlus® Tool Guide, have also proven popular in helping manufacturers assess the best turning inserts and grades for their requirements.
To help with process monitoring itself, Sandvik Coromant has also developed
CoroPlus® Process Control software that can monitor machining in real time and act according to programmed protocols if specific issues occur—for example, by stopping the machine or replacing a worn cutting tool.
A perfect circle
This brings us to the UN's second recommendation for more sustainable tooling: moving to a circular economy, where waste products are seen as raw material and put back into a resource-neutral cycle. It is increasingly clear that a circular economy can be both environmentally sound and profitable for manufacturers.
This includes recycling solid carbide tools—after all, we all come out as winners when worn-out tools are kept out of landfills and junkyards. GC4415 and GC4425 each contain a significant amount of recycled carbide. Making new tools from recycled solid carbide requires 70% less energy than making them from virgin raw materials, and it also results in 40% less carbon dioxide emission.
Then there is the
carbide recycling program from Sandvik Coromant, available to all our customers worldwide. The company buys back worn inserts and round tools, regardless of origin, from its customers. This is really necessary if you consider how finite and scarce raw materials will become in the long run. Estimated reserves of tungsten, for example, are around 7 million metric tons, which leaves us with about 100 years of consumption. The recycling initiative has brought Sandvik Coromant to 80% circularity through the carbide buy-back program.
Despite the current market uncertainties, manufacturers cannot forget their other obligations, including CSR. Fortunately, with a new approach to tooling and the right carbide inserts in place, manufacturers can improve their sustainability without compromising process security—and do so more effectively while facing the challenges created in the markets by COVID-19.