| Technical
Information
The determination of the correct speeds and feeds to be used with
disposable tipped cutters cannot be given exactly as it depends
on a large number of inter-related factors which vary from job to
job. However, general guidelines can be given which should result
in a good starting point for further refinement.
The basic starting point is to determine the cutting speed to be
used. The table below shows a range of materials commonly encountered,
with a range of cutting speeds for each group of materials. Where
natural timbers are being used , consideration should be given to
the hardness of the timber in terms of the tendency of the fibers
to lift or split, the abrasive quality of the material, and so on.
Your timber supplier can often give detailed information on the
features of the material they are supplying and recommend suitable
cutting speeds and feeds.
Man-made materials are very much more consistent in their machining
characteristics and similar speeds and feeds can be used from batch
to batch.
| Material |
Cutting Speed (metres/sec) |
| Hardwood |
60-100 |
| Softwood |
50-90 |
| Chipboard |
50-80 |
| MDF |
40-65 |
| Plywood |
50-80 |
| Plastic laminated board |
40-60 |
Rotational Speed R.P.M
| Diameter |
40M/sec |
50M/sec |
60M/sec |
70M/sec |
80M/sec |
| 25 |
20,000 |
20,000 |
20,000 |
20,000 |
20,000 |
| 50 |
15,000 |
19,000 |
20,000 |
20,000 |
20,000 |
| 75 |
10,000 |
12,000 |
15,000 |
18,000 |
18,000 |
| 100 |
7,500 |
9,500 |
11,500 |
13,000 |
13,000 |
| 125 |
6,000 |
7,500 |
9,000 |
9,000 |
9,000 |
| 150 |
5,000 |
6,500 |
7,500 |
7,500 |
7,500 |
| 175 |
4,500 |
5,500 |
6,500 |
6,500 |
6,500 |
| 200 |
3,500 |
4,500 |
5,500 |
5,500 |
5,500 |
Determination of Feed Speed
The calculation of the optimum feed is dependent on a number of
factors and these must be taken into consideration in order to reach
a satisfactory solution. The factors affecting the feed rate will
be the size and rigidity of the cutter together with the chip space
available. On very small cutters, the cutting edge has limited chip
space and lower rates of feed are necessary otherwise breakage will
occur.
On the other hand, too low a feed rate will cause the cutter to
rub rather than cut.
Machine and job rigidity is another factor which must be considered.
Parts must be adequately located and rigidity held.
Low feed rates will create a better finish than high feed rates.
The proposed feed rate can be easily calculated as shown below.
Suggested Chip Thickness
| Material |
Chip Thickness (mm/Tooth) |
| Hardwood |
0.2 - 1.7 |
| Softwood |
0.3 - 0.8 |
| Chipboard |
0.3 - 0.8 |
| MDF |
0.3 - 0.6 |
| Plywood |
0.3 - 0.6 |
| Plastic laminated board |
0.3 - 0.7 |
Let Z = number of wings on the cutter.
N = Rotational speed of cutter in R.P.M
C = Chip thickness
Then FEED RATE in meters / min = (N * Z * C) / 1000
Example:
For a 2 wing cutter, rotating at 9000 r.p.m, with a proposed chip
thickness of 0.3 mm, the feed rate will be:
Feed rate = (2 * 9000 * 0.3 Meters/min ) / 1000 = 5.4 Meters / min
|
Router
Tools
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