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Leistritz-Group
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 What is Whirling?Whirling Makes Economic Sense!
The Cutting Process and Chip Formation The cutting angle of the tool head is controlled about “A axis” to correspond to the pitch angle of the thread. The eccentricity of the “X axis” determines the minor diameter of the thread. By simply changing the “Z axis” travel direction either right or left-handed threads can be machined. But in each case the whirling ring always rotates in the same direction as the workpiece, it’s the direction of travel that yields the desired left or right hand threads. The cutting tools are mounted in the tool ring, and move relative to the workpiece. The chips generated from this cutting process are ideally comma-shaped, (see figure 2). Although whirling is an interrupted cutting process the smooth chip formation is such that hardened material to 65 HRc and brittle material can be cut, with either carbide, CBN (Cubic Boron Nitride) or with ceramic tools.
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Comparing Whirling with Milling
When cutting external threads, we first must look at the similarities between whirling and milling. A whirling ring has multiple cutting teeth similar to a milling cutter.
Each cutting edge removes a certain amount of material during the noncontinuous cutting operation. But that’s where the similarities end.
Whirling has a more favorable cutting action, due to the gradual entry and exit of the insert cutting edges, allowing greater metal removal rates. This smooth cutting
action reduces radial pressure, creating less stress on the workpiece and insert. Also tool life is significantly extended making the process even more cost
effective (see figure 3).
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Figure 3 s Chip size |
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What is Whirling? To further compare, tests show that the surface finish quality of whirling is comparable to that of grinding. This is directly related to the longer insert-to-workpiece contact time, resulting in not only shorter but also fewer polyhedral peaks. In short the Leistritz easy-to-use tooling system combined with the benefits of whirlings faster machining times and surface finish quality, clearly show that whirling is today's most economical and cost effective solution to produce external threaded parts. Whirling is a manufacturing operation in which "a geometrically oriented cut removes material”. Whirling removes material similar to that of milling however, in whirling the cutter uses carbide inserts arranged along the inside circumference of a ring. A system developed by Leistritz AG of Germany utilizes a whirling ring with a predetermined cutting circle diameter calculated from the thread or worm data (OD, pitch and depth). |
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