Following last year’s launch of PrimeTurning™ methodology and tools for external turning operations, Sandvik Coromant is now introducing a dedicated CoroTurn® Prime SL head that makes this groundbreaking process available for internal turning operations. The new SL head will cater for the needs of oil and gas, aerospace and other manufacturers machining diameters in excess of 90 mm (3.5 inch), and overhangs up to 8-10xD.
“The inside-out machining capability provided by the CoroTurn Prime SL head solution in combination with PrimeTurning techniques, promotes excellent chip evacuation and chip control,” states Hakan Ericksson, Product Manager – General Turning, Sandvik Coromant. “In turn, manufacturers can achieve an excellent surface finish, matched by high productivity, longer tool life and high machine utilisation.”
In contrast to conventional internal turning, PrimeTurning sees the tool enter the material at the chuck end of the component and remove metal as it travels back out towards the bore exit (inside-out direction). This allows for the application of a small entering angle that offers significant productivity gains. However, if required, another variant is also available with a reversed tip seat that makes it possible to perform PrimeTurning in the opposite direction (outside-in).
There are two insert types for internal PrimeTurning: A-type for profiling, finishing and light roughing; and B-type for roughing to finishing operations.
Speed and feed rates can effectively be doubled with PrimeTurning. This is because the small entering angle and higher lead angle create thinner, wider chips that spread the load and heat away from the nose radius, resulting in increased cutting data and/or tool life. Furthermore, as cutting is performed in the direction moving away from the shoulder, there is no danger of chip jamming, a common and highly undesirable effect of conventional internal turning.
With CoroTurn Prime SL heads, customers can create a wide range of tool combinations from a small inventory of adaptors and cutting heads. SL heads are available in 40 mm (1.575 inch) diameter, and fit with solid steel bars and carbide bars, as well as with Silent ToolsTM damped boring bars for vibration-free internal machining.
In a further development, Sandvik Coromant can now offer the new -H3 geometry to eliminate any concerns about chip control, which can be challenging when machining low-carbon and high-strength steels. The -H3 geometry is available for B-type inserts in grades GC4325, GC1115 and H13A.