We get asked from time to time if we can make form tools on a helically fluted tool. We reply by telling them “we certainly can!” Our dedicated ANCA programming system can project the cutting edge across a helix with relative ease. The 5-axis grinder picks up the programmed numbers and produces the final form very accurately and consistently.
Why would a helical-fluted form mill work better than a straight fluted one?
They are the same exact form tool except for the helix. In the upper tool pic, the helix is 20 degrees with a 14 degree hook angle. A straight flute, on the other hand, has a 0 degree helix. There is no hook angle.
Although it is easier to make and check a straight fluted form, the tool will not work as efficiently in removing metal as the helical form. On a straight-fluted tool, the entire cutting surface will contact the metal at once creating a divot into the metal shaped like the form. Then next flute comes around and creates another divot. As the tool rotates and the table advances, the metal is removed steadily and the form is milled onto the part.
The drawbacks of a straight flute mill are:
- The form hitting over and over create a slapping or pounding situation and harmonic chatter can develop.
- The finish will not be as good at the desired feedrate so it must be slowed down to obtain a good finish.
- Because the tool has a neutral flute rake, and a resultant lack of efficiency in tool geometry, the form may suffer due to deflection of the holder, machine tool, fixture, or all three. This makes it more difficult to make the form in the specified tolerance, even when the tool form is perfect. (Which our tools always are!)
The benefits of a helical fluted tool are:
- The tool has a positive hook angle in the flute, therefore the chip is formed in a more efficient manner and the material is removed faster and quieter.
- The helix of the tool creates a spiral cutting effect which greatly reduces tool pressure. This makes the form more accurate because the deflection is reduced.
- The tool lasts longer due to less pounding and chatter which is bad for the brittle carbide edge.
- If the tool edge holds up better, you can get more regrinds from it, saving you money.
When deciding on a custom tool for your milling app, please consider KV Tooling System’s tool design and manufacturing service. We want to serve you so you can better serve your customers.