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HEMI engine cutaway. This 470-hp engine used in the Dodge Charger SRT8 features aluminum heads and a cast-iron block. Word from people involved in the development of cutting tools, the amount of aluminum in applications like powertrain will continue to rise, and yet cast iron isn’t going away.
While the machining of superalloys—like Inconel, Waspaloy, and Stellite—is something more characteristic of aero than auto, downsizing and lightweighting may lead to these materials playing a role—perhaps minor, but a role nonetheless—in auto. Shown here is a silicon nitride ceramic insert from Walter USA (walter-tools.com/us)turning an Inconel 718 component. Among Walter’s grades in this arena are WIS10, a sialon ceramic that can handle light roughing to semi-finishing, and WWS20, which has silicon carbide whiskers that add toughness to the insert, which means it can turn forged or cast out-of-round workpieces, including hardened steel.
Although there continues to be a drive toward more near-net shape castings, let’s face it: there is still a need to perform roughing and cubing in cast iron and steel. This is tough on tools because of the changes in the surfaces being milled. So Sandvik Coromant (sandvik.coromant.com) has developed the CoroMill 357, a multi-edge face milling cutter that houses double-sided, thick, pentagonal inserts in shim-protected tip seats. Can take a depth of cut up to 10 mm with a feed per tooth up to 0.7 mm/Z. Available in diameters from 100 to
ISCAR (iscarusa.com) has been producing indexable inserts with a helical cutting edge for a number of years. But with the HELIQMILL 390, it is upping the insert as this one features three cutting edges, not the two of its predecessors. Yet the length of the cutting edge of the new insert is the same as its predecessors: 10- and 15-mm lengths. It has a stronger structure and it is clamped into the tool pocket with high rigidity, thereby making them reliable and accurate in machining shoulders, slots, and planes, as well as surfaces, and performing helical interpolation for pockets or cavities.
Slotting, shouldering, ramping, facing, pocketing, plunging, and turn milling are all applications that can be performed by new cutters added to the Seco Tools (secotools.com) Turbo 10 series of square shoulder milling cutters. The cutters range in diameter from 20 to 54 mm. There are precision-milled pocket seats. Integrated through-coolant channels facilitate chip evacuation. Aluminum, stainless steels, titanium alloys, and other materials can be addressed by inserts in the lineup. There are both direct-pressed and ground-inserts. Corner radii range from 0.4 to 3.1 mm.
Holemaking is facilitated by the Drill Fix series for short holes from Kennametal (kennametal.com). There is the DFR line, which has a diameter range of 12.5 to 24 mm; it produces holes 2 to 4 × D. It uses rectangular inboard and outboard inserts so there are soft starting cuts and short chips; they allow higher feedrates. The DFT line is available in a diameter range of 24 to 82 mm. And there is the DFS line that uses a trigon inboard insert to facilitate accurate centering.
Some things remain the same. But there are also significant changes in the area of cutting metal.
The nature of metal removal in the auto industry is more of the same and more of what has not been done in any notable volume.
The former is the burgeoning use of aluminum for things ranging from engines to suspension components. There will be, so the people we talked with in the cutting tool industry believe, an on-going use of aluminum throughout the industry. Which, from the point of view of an insert, typically means there will be a high positive design, which has the result of reducing the number of cutting edges on the tool. And while there is this increase in the use of aluminum, there is, we’re told, still a lot of cast iron machining continuing. But in this arena, there are some changes coming, like an increase in the use of CGI—compacted graphite iron. While this is not unfamiliar to people who are machining things like blocks for diesel engines, this has not been the case in light-duty gasoline engines, but a change may be on the way. And while it might seem that the learnings from the diesel engine machinists would be readily ported over to the gas engine guys, the word is that there is a difference in the way the two tend to machine, with the former being more conservative and the latter being more aggressive, so there needs to be changes to the tools, everything from the geometries to the coatings to the substrates.
And as for the more of what has yet to be done in any notable volumes, the word here is that carbon fiber reinforced plastic (CFRP) components are going to present a whole lot of challenges to those who are responsible for machining the strong, light material. Here, there may be some things that can be gleaned from companies like Boeing and Airbus, which have been using CFRP as a matter of course for some time now. And while on the subject of aerospace, which has long been using superalloys and other exceedingly difficult-to-machine materials in engines and other components, as auto engines are downsized and turbocharged, there may be the use of combinations of materials, including the tough-to-machine alloys, so it might be worthwhile for auto manufacturing engineers to take a closer look at what their brethren in aero are up to.
And in the mean time, the cutting tool manufacturers will continue to produce the types of tools that will allow increased metal removal rates. Like some of the products you’ll find here.*
*Special thanks to Sandvik Coromant and Walter USA.