In this video, we discuss cutting tool performance with Dave
Sawyer, territory manager at Kyocera
SGS. Sawyer gives us a quick rundown of tools optimized for tough jobs in the
aerospace industry, suitable for cutting materials ranging from 6061 aluminum
to tougher stock like Inconel and titanium. As an example, he shows us a
5-flute cutter that allows for roughing and finishing with the same tool while
still delivering an 80 RMS finish.
Normally, higher feeds and speeds come at the cost of finish
quality. Of course, a higher feed rate will result in a lower finish quality,
but it also removes material faster. To improve finish quality, you have to make
smaller passes, and thus remove less material.
According to Sawyer, a 3-flute cutter typically offers
better stability than 4- or 6-flute cutters. The geometry of the tool offers
better chip clearance, and that increased stability improves the load, which in
turn improves speed.
On the other hand, you can keep a higher feed rate going
with the 5-flute tool. A center hole for delivering through coolant and
channels that flush coolant down the sides of the tool to avoid re-cutting
chips allows operators to push the tool faster without having to worry about
chip clearance and tool destruction.
High speed machining (HSM) has brought higher rpms, with
many spindles running at 33,000 rpm today. With that high speed comes with
higher-torque motors. For example, you can bury a 3-flute ¾” cutter at 33,000
rpm into aluminum at 0.500” depth of cut, pushing 900 inches per minute
roughing out a slot.
Aerospace Machining Materials: Titanium and Aluminum
Machining titanium and titanium alloys such as Ti-6Al-4V (also
known as TC4) is difficult due to the material properties of the metal. Titanium
has high chemical reactivity, causing it to be more inclined to smear, weld or
gall in the high-heat, high-friction environment. It’s also a poor conductor of
heat, unlike steel or aluminum (which has one of the highest heat
conductivities of the common metals). As a result, heat builds up at the tool
face. Titanium is also elastic, making vibration an even bigger issue.
When cutting titanium, be sure to use sharp tools and the
correct fixturing to provide the maximum possible rigidity. This will help
reduce problems caused by chatter.
While many machinists say that aluminum cuts like butter,
that doesn’t mean there isn’t the potential to lose productivity and time
cutting it. When you’re removing a lot of material in one pass, you run the
risk of damaging tools by re-cutting chips. Chatter can also be an issue. To
deal with machining vibration, take the following steps:
·
Reduce exciting frequencies (spindle speed,
number of teeth)
·
Use tools that reduce vibration (sharpness,
angles, size)
·
Make sure that your machine, tool and workpiece
are as rigid as possible
For more on specific Kyocera tools, and Sawyer’s tips for
making the most of your machining, watch the video above and visit the website
of Kyocera SGS.
Stay tuned for another video on high-performance cutting
tools, this time about Avitec’s highly polished cutters for chip removal,
finish quality and tool life.