SGS Carbide Tool's JetStream patented approach to coolant delivery offers benefits

Although the development has been successfully applied in the field already, details have not been widely publicised. Its benefits are particularly relevant to those machining titanium, stainless steels, Inconel and other difficult-to-machine materials, with a doubling of tool life having been achieved in some cases. Indeed, it has become de rigueur for its Z-Carb-AP tools in aerospace roughing applications, says the company. Called JetStream, the system is applied to solid carbide tools and sees 'channels' ground on the top and side the shank, with these then intersecting with more channels that run down the flutes. This delivers coolant to the shear zone – the interface between the cutting edge of the tool and the raw material of the workpiece that is being cut. The coolant helps maintain thermal stability, provides lubrication for the cutting action and also flushes the swarf away to reduce the chance of 'stirring', or re-machining, of chips. The development offers superior tool strength, compared to the alternative of through-tool coolant channels, as executive vice president of manufacturing Jeff Burton explains: "Coolant holes have a slight weakening effect on the business end of the tool, and in cases where the hole or holes only exit the end, the tool needs to be over the workpiece for the coolant feed to be effective. "JetStream does not weaken the tool and it provides cooling when the tip is not over the workpiece. The two methods could be used together, providing the coolant pumping capacity of the machine tool is sufficient. However, in many cases customers will also want to run the flood coolant. JetStream efficiently removes the chips out of a pocket or slot, but they can accumulate on the workpiece top surface and need to be removed by some means, such as flood coolant." Water-miscible coolant at the coolant suppliers' recommended strength of usually 5 to 8% is fed via the X channel ground into the back of the tool shank. This feeds the coolant to the side grooves that transfer the fluid to the shear zone. The exact grinding profile of the slots used is a closely guarded secret. Although they are open channels, the slots retain the cutting fluid, even at elevated spindle speeds. Says Burton: "We have tested JetStream in aluminium at up to 10,000 rpm. At that speed, with 1,000 psi coolant pressure, and using a standard length tool, the effects of centrifugal force were minimal and JetStream was still effectively delivering the coolant precisely to the targeted area. JetStream has become a must on Z-Carb-AP roughing aerospace applications, in some cases has doubled tool life when applied to titanium, stainless steels, Inconel and other difficult to machine materials." He concludes: "It is a fact that the correct application of coolant can improve tool life and reduce cutting loads, as well as improve machining accuracy and surface finish. With JetStream technology manufacturing businesses can be sure that the coolant is reaching the correct location – the shear zone. We find it particularly beneficial during deep slotting or pocketing operations, where normal flood cooling has difficulty removing the chips."