A manufacturer concerned about the impact "W" is having on metalworking might not be thinking about the guy in the Oval Office. W is the chemical symbol for tungsten.
This year, tungsten prices have shot up. Focused on its own consumption of the metal, China recently took steps to reduce its tungsten exports. Such a move can’t help but have an impact. One news organization that covers metals and mining estimates that China controls 75 percent of the world’s tungsten reserves and supplies 85 percent of tungsten consumption. The largest share of the impact goes to carbide products such as cutting tools, with cemented carbide accounting for more than half of all the tungsten demand. When tungsten prices go up, cutting tool suppliers feel the price pressure.
Product managers with Ingersoll Cutting Tools in Rockford, Illinois, point to an important and interesting consequence. Cutting tool users, they say, are taking a second look at milling and drilling tools that use carbide only at the tip. These tools offer a cost-effective compromise between high speed steel tooling and solid carbide tools.
These replaceable-tip tools are not "inserted" tools, per se. Instead, this tooling brings the principle of inserted carbide down to small-diameter tools that normally would not be a candidate for replaceable inserts. The complete replaceable tip either screws in or fits rigidly into the steel body, which acts as a toolholder and is therefore independent of the tool life of the carbide. Two examples of this tooling (from Ingersoll) are illustrated in the photos above: a "QwikTwist" drill featuring a replaceable point, and the "ChipSurfer" modular milling system.
There was always a case to be made for these tools in terms of cost savings. A change in carbide prices simply shifts the argument toward the up-front purchase price of the tooling, as opposed to more subtle costs. However, the subtle costs affecting tooling choices are still every bit as real.
For example, replaceable tips can be swapped out right at the machine tool, with the tool shank remaining in place. Because of the accuracy and repeatability with which the tip locates (as low as ±0.0005 inch axially and radially, the company says), tool offsets values do not have to be re-measured, which saves time.
Other sources of savings relate to inventory. When solid carbide tools are re-ground, the shop has to own enough tools so that a certain number of them can remain in the re-grinding buffer (known to some as tool "float"). A shop that needs to have two of a particular solid carbide drill available might need to own six of these tools just to account for the regrinding delay. Using tools with replaceable tips can do away with this inventory and, perhaps even more significantly, it can do away with the expense and attention of tracking all of these tools.