Why
it is fine if your router bit has many cutting edges ...
1.
The cutting edge is the wear part of your bit. The more cutting edges ou have,
the more share the wear, the longer normally your bit lasts (="tool
lifetime").
2.
A cutting tool with several cutting edges is better balanced as a bit with
only one edge.
3. The bigger cross section area
covered by carbide (instead of "air") allows an easier
transportation of the heat caused by the cutting process towards the chuck and
the spindle. This is especially valuable if there is no further possibility to
cool the tool.
4. The more cutting edges your cutter
has, the smaller the chips, the smoother normally the surface of your
workpiece will be.
Why it is fine if your
router bit has just one cutting edge ...
1.
The main problem within the process of milling a slot is adhesion of chips
within the chipflute of the tool and obstruction of the tool caused by this.
Once obstructed the bit will no longer transport the chips towards the surface
of the material and the feed force of the machine brakes it. That may happen -
depending on the material - long before the cutting edge is dull. So the most
important question is: "Which way the chips shall go?". Common
answer: "Upwards or th the back of the cutter into the slot" (exempt:
downcut bit). For this reason you need space (=chipflute), to carry the chips
away. The comparison of the cross-section of various types shows that a single
tooth cutter provides the largest open area (= biggest cipflute) and that the
open area descends with the increase of the number of cutting edges.
2. When milling aluminium or plastics
the application of single flute cutters with polished cutting edges and
chipflutes has proven to be the best choice, normally. The polished surface of
the chipflute makes it almost impossible for the chips to aggregate to the
surface of the cutter or to create a built-up edge (aluminium).
3.
The less cutting edges a router bit has the easier the plunge operation into
the material will be. What
is more important?
The question what will be the most suitable
cutter for a certain application can only be answered by examining the whole
process including the routing system, its spindle, cooling, clamping, chip
removal, etc. So this can only be a rough rule of thumb: For cutting plastics
(PVC, acrylic, cellular foam plastic), wood and wooden composits (chipboard),
non-ferrous metals (soft aluminum, aluminium composits, copper, brass, ...)
normally a one flute cutter will be the best choice because the problem of
cutting edge erosion remains far behind the problem of obstruction.
Foy very hard plastics or aluminium alloys (short chipping) a two fluted bit
may be the better choice, but always take care for excellent smooth and sharp
cutting edges and large chipflutes.
For steel normally you will use a bit with 4 or more cutting edges, the number
depends a little on the diameter of your cutter. In our opinion the
application of a tool with more than 2 cutting edges will be of advantage only
if the cutting diameter is equals or larger than Ø 6 mm. |
