In this video, we spoke with Tony Pugliese, plant manager at
Avitec Tools, a Montreal-based company. One
of Avitec’s specialities is polished cutting tools: mills and cutters with a
special mirror finish, which Avitec claims provides numerous benefits including
better sharpness, better chip clearance, higher quality finish and longer tool
life. To hear it from Tony himself, click to watch the video.
Aluminum is such a commonly machined material that it’s easy
to overlook the pitfalls. While aluminum may cut easily, faster cutting means
more chips—and
if your tool can’t clear chips out of the cut fast enough, it’s bad news.
With most setups, chip clearance is a matter of tool flute
geometry and coolant. Some tools, such as the ones described in our recent
interview with Kyocera SGS, have a centre hole drilled in them for through
coolant, or channels that flush coolant down the sides of the tool. These
coolant delivery methods can help drive chips out of the cut faster, but the
main mechanism of chip clearance is chips sliding up the tool geometry and
away.
According to Avitec, a mirror finish on the flutes of the
cutter reduces friction, making it easier for chips to slide out of the cut
faster. That’s one reason for their polished cutting tools; another is
sharpness.
In high-speed machining of aluminum, you want to cut with as
sharp a tool as possible. With a sharper tool, you can get faster cutting, longer
tool life and a better finish. Avitec’s tools have no coating, only a ground
finish to the steel. This is because a coating creates a tiny, micron-sized
radius on the cutting edge, reducing sharpness. Avitec believes that the
benefits of this polished steel outweigh the disadvantages of no coating.
Avitec developed their polished cutting tools in response to
a German customer who would send tools in to Avitec to be re-sharpened every
week. Recognizing the need for tools that would stay sharp longer, the company
manufactured their first polished tool, made of steel with brazed carbide
inserts. They drilled 55,000 holes before deciding the tool was good enough for
market.
Any opportunity to reduce the need for tool changes is an
opportunity for faster cycle time. According to Pugliese, you can go from
roughing to finishing without changing tools. Simply reduce the depth of cut,
maintaining feed and speed. For roughing, you would make a bigger pass,
removing more material. For finishing, you can keep the same feed and speed,
but make a smaller pass. A faster cut allows the tool to push a little bit
against the workpiece, and this added friction improves the surface finish.
Besides being polished to what looks like jewelry standards,
the tools have very accurate concentricity, at 0.0002”. This low runout is
essential for surface finish, as even a small amount of runout will create
tooling marks. Lastly, another benefit of highly polished cutters is reduced
friction, meaning less heat buildup. This is essential in high speed machining.
For more on new innovations in cutting tools, check out Increasing
Tool Life and Decreasing Energy Waste with Cryogenic Machining.
Stay tuned for more videos filmed on the show floor at CMTS
and FABTECH.