Back in the seventies, ISCAR introduced SELF-GRIP, the brand name of the original parting tool design concept. The concept of the SELF-GRIP tool (Fig. 1) was a pressed carbide insert clamped into a tool blade using the blade’s elastic forces without the need for mechanical securing elements. The SELF-GRIP tool proved to be a game changer in parting.
ISCAR quickly established its name as an authority in parting applications. Today, ISCAR’s ongoing inventions of new parting tools continue to attract great interest.
In parting, the rigidity of insert clamping is a key factor. The desire to achieve economical use of workpiece material dictates the ultimate reduction in cutting width. An increase in the diameter of the workpiece leads to an increase in the tool’s overhang. The narrow width of the insert and the blade can degrade the tool’s dynamic behaviour and ultimately affects machining performance. Improving rigidity and increasing strength to assure effective cutting are key factors when designing a parting tool.
The SELF-GRIP has been upgraded and expanded and the evolution exemplifies a logical progression of highly engineered solutions throughout several generations of R&D engineers. Pinpointed high pressure coolant (HPC) provides advantages for better parting performance by decreasing cutting temperatures by assuring excellent chip breaking, which improves surface finish and prolongs tool life. In machining difficult-to-cut heat-resistant superalloys and austenitic stainless steel, HPC reduces or even eliminates the built-up edge phenomenon.
The production of effective inner coolant channels in thin tool blades is a difficult engineering task. One of the ISCAR solutions is the DO-GRIP parting tools, which carry an insert with two cutting edges. The edges are twisted relative to each other; thus, the non-working edge does not limit the cutting depth of the tool. (Fig. 2).
The PENTACUT family of star-shaped carbide inserts were originally designed for parting small diameter workpieces. These inserts provide five cutting edges and are clamped in the pocket by a screw that passes through the insert’s central hole. The evolution of 5 cornered inserts proved difficult when cutting large diameter workpieces. The insert needed to grow, making the task problematic and economically impractical. The solution was the PENTA-IQ-GRIP – parting tools with five cutting edges. They enable parting in diameters up to 40mm with an innovative dovetail securing principle. The tools utilise relatively small inserts. In addition, there are PENTA-IQ-GRIP tools with an HPC option (Fig. 3).
The SELF-GRIP concept used the elastic behaviour of a parting blade. This paved the road for the TANG-GRIP which functions on the principle of support for the insert to counteract cutting forces applied on the tool. (Fig. 4). The orientation of the insert pocket was changed compared to the SELF-GRIP tool design, and therefore support is achieved by the long and rigid rear wall of the pocket. TANG-GRIP has a solid stopper, unlike the friction retaining force that characterises most parting systems that feature a self-clamping insert. This eliminates insert pull-out.
There is also another side of the ‘parting’ coin – increasing the feed rate causes an increase in cutting forces. This worsens when the bar diameter and depth of penetration become larger, resulting in blade deflection. The method of utilising Y-axis parting is a way to overcome the problem. Y-axis parting is common on multi-tasking machines with a Y-axis drive that assures appropriate feed motion.
Compared to traditional parting, Y-axis parting improves the dynamic behaviour by using tangential cutting forces. When parting in the direction of radial forces, blade rigidity is reduced. Once again, ISCAR invented a solution with the LOGIQ-F-GRIP, a new tool family characterised by a square adapter with four inserts mounted on each of its cutting tips. (Fig. 5). The adapter combines both blade orientations (in X and Y-directions) which provide a balanced-rigid design. The adapter has 4 insert pockets and prolongs tool life.
When searching for the right parting tool, all manufacturers stand at the parting of the ways. ISCAR’s milestones in creating parting systems demonstrates its commitment to advanced solutions to meet customer demands.
