What is the difference between a downcut, upcut and a down-upcut cutter? Which cutter to choose for cutting, grooving and surface cutting?
In this article, we will look at the use of spiral cutters and what are the differences between them.
Spiral cutters are most often used for cutting in CNC machines, but of course it is also possible to use them in top router machines.
The basic tasks of spiral routing cutters are material cutting or grooving.
Spiral cutters are most often used for cutting hardwood or plywood.
A spiral cutter is an all-carbide tool with a precisely formed spiral that has the blade ground in a downcu, upcut, or downcut-upcut inclination to the direction of rotation.
You will use material division especially for precise formatting of the part. Spiral routing cutters can also be used for drilling or 3D cutting.
Now we will look at the individual types of cutters in detail.
Downcut
The downcut spiral cutter, as the name suggests, is ground in a downcut inclination, ie against the direction of rotation. This guarantees chip evacuation to the bottom
This cutter is not suitable for grooving. There is a risk that the routed material will accumulate in the groove (the cutter will start choking) and there is a risk of damage to the tool.
The downcut spiral cutter has excellent cutting quality at the upper edge and lower chip evacuation
Lower chip evacuation
Upcut
The upcut spiral cutter has a sharpened edge in the positive direction. Imagine a cutter that has a spiral like a classic wood drill. When drilling a hole, the chips are pushed in the same direction. And this is also the case with this routing cutter, where during routing the wood waste is pushed upwards towards the clamping shank.
You will use this fact when grooving, when the groove will not be filled with chips.
The upcut spiral cutter has excellent cut quality at the lower edge and upper chip evacuation.
Upper chip evacuation
Up-downcut
The up-donwcut spiral cutter has a halved blade at the bottom with a positive slope and at the top with a negative slope.
The up-donwcut spiral cutter has a perfect cut quality without burrs on the lower and upper edge. When cutting the entire cutting part of the tool, the chips will be gradually removed from the top and bottom. It is therefore ideal for formatting or final cropping of the part.
Chip evacuation up and down
We will explain you the concept of sequential and non-sequential cutting.
The material can be cut sequentially and non-sequentially. Sequential cutting means that the tool is guided in the direction of rotation of the tool, while non-sequential cutting is the opposite, i.e. the sequential cutter is guided against the direction of rotation of the tool.
Non-sequential
The cutter is guided against the direction of rotation of the tool.
Sequential
The cutter is guided into the material in the direction of tool rotation.
How do spiral cutters work when formatting a part, ie. with a straight cut?
Downcut spiral cutter
Non-sequential
Downcut spiral cutter is guided non-sequentially into the cut. During cutting, it can be seen that the chips are led down from the cutter and a clean cut is at the upper edge of the workpiece.
Sequential
Downcut spiral cutter is guided sequentially into the cut. Sequential cutting is more gentle on the blade and the tool itself.
Upcut spiral cutter
Non-sequential
When cutting with an upcut cutter it can be seen that the chips are led upwards from the cutter and a clean cut is at the lower edge of the workpiece. The cutter is guided non-sequentially into the cut.
Sequential
The second cut with an upcut cutter is guided sequentially into the cut. Sequential cutting is also more gentle on the blade and the tool itself.
Up-downcut spiral cutter
Non-sequential
When cutting with an up-downcut cutter, it can be seen that the chips are removed from the cutter both upwards and downwards. The clean cut is on both edges of the workpiece. The cutter is guided non-sequentially into the cut.
Sequential
The second cut of the up-downcut cutter is guided sequentially into the cut. Sequential cutting is also more gentle on the blade and the tool itself.
The differences between spiral cutters when grooving at 5 and 10 mm depth.
Dowcut spiral cutter
When using a downcut cutter, we can see a clean cut at the upper edge.
When cutting a 10 mm groove, it is obvious that the groove is filled with chips. There is a risk that the cut material will accumulate in the groove (the cutter will start choking) and there is a risk of damage to the tool.
Upcut spiral cutter
When using a upcut cutter, we can see burrs on the upper edge of the cut.
When cutting a 10 mm groove, it is obvious that the chips are removed from the groove upwards. When cutting deeper grooves, there is no danger that the cut material will accumulate in the groove.
Up-downcut spiral cutter
When using an up-downcut cutter, it depends on the depth of immersion.
If the top edge is frayed, it can be seen that only the upcut part of the tool has been cut with, which we see in the case of cutting a 5 mm deep groove. When cutting a 10 mm deep groove, the downcut part of the cutter is already cut with, and therefore the upper edge is not frayed.
Gradual plunging and cutting into the surface of the material.
Downcut spiral cutter
When using a downcut cutter, a clean cut is visible at the top edge. Chips are removed downwards, but there is no risk of chips accumulating during gradual plunging.
Upcut spiral cutter
When using a upcut cutter, we can see burrs on the upper edge of the cut.It is therefore more advantageous to use a downcut cutter when cutting into the surface.
Up-downcut spiral cutter
When using an up-downcut spiral cutter, it depends on the depth of immersion, as we already mentioned in the case of grooving.
Summary at the end
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Downcut spiral cutter
- Excellent cutting quality on the upper edge and lower chip evacuation.
- Suitable for gradual immersion.
- Not suitable for cutting deeper grooves.
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Upcut spiral cutter
- Excellent cutting quality at the lower edge and upper chip evacuation.
- Suitable for cutting deeper grooves.
- Not suitable for gradual immersion.
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Up-downcut spiral cutter
- Perfect cut quality without burrs on the lower and upper edge.
- When cutting the entire cutting part of the tool, the chips will be gradually removed from the top and bottom.
- Ideal for formatting or final cropping of a part.
We offer you both downcut, upcut and up-downcut spiral cutters with a smooth edge, which one can use for precise formatting, as well as roughing cutters, which are used for cutting the rough dimensions of the part. Also of interest are cutters with a special chrome-plated surface for longer tool life.
So this is it. Make sure to also check out the video at the beginning of this article.