Dear Sirs. Normally I use internet on-line machining calculators to estimate cutting forces and cutting power for differents machining operations. While many of these use sofisticated variables like edge wear, rake angle, none consider the influence of tool point radius. Which may be the reason? How much error can cause in the calculation, do not take it into consideration?
Hi Daniel,
The effect of cutting edge radius on cutting forces is significant in micro-machining (when the undeformed chip thickness is lower than its cutting edge radius). However, the effect of cutting edge radius on cutting forces reduces with increasing the undeformed chip thickness. This is known as the size effect.
Please note that cutting edge radius will affect surface roughness of the machined surface, and the tool wear rate.
Cheers,
Silvie
Hi Daniel,
The effect of cutting edge radius on cutting forces is significant in micro-machining (when the undeformed chip thickness is lower than its cutting edge radius). However, the effect of cutting edge radius on cutting forces reduces with increasing the undeformed chip thickness. This is known as the size effect.
Please note that cutting edge radius will affect surface roughness of the machined surface, and the tool wear rate.
Cheers,
Silvie
Daniel
The minor nose radius and the nose angle are important for reducing the fluctuation of the forces in machining processes.
The variation of undeformed chip thickness make the change of chip sectional area, and it causes vibration because the forces are modified too.
As general rule, the depth of cut should be greater than or equal to 2/3 of the nose radius and feed rate should be less to 1/2 of the nose radius to this variation be minimum.
Att.
André
You can used it to evaluate it but to measure, it is better to use a measuring device. Go noline and check for device that can measure cutting force
Yes, cutting tool nose radius influences the cutting forces. Larger nose radius gives better surface finish but at the cost of life of the tool in hard turning.
Cutting tool nose radius also causes the changes chip flow direction.
And what about any formula to estimate the force value in function of tool nose radius, please?
Hi Daniel, I am sorry I misinterpreted tool point radius with cutting edge radius.
For cutting tool nose radius, usually it's used to control surface roughness and chip breaking. So far, I have not came across any formulas that actually uses tool nose radius to calculate cutting forces.
Using large tool nose radius should produce better surface roughness. However, large tool nose radius also means higher radial forces. This tends to cause vibration, which will cause bad surface roughness. In order to reduce vibration due to large nose radius, you increase the depth of cut. As what Andre J. Souza mentioned earlier, the depth of cut should be greater than or equal to 2/3 of the nose radius and feed rate should be less to 1/2 of the nose radius. I learned the same rule of thumb as well.
Using small tool nose radius tend to help with chip breaking. However, small tool nose radius also means that it has weaker edge.
If you are looking to estimate or predict the effect of tool nose radius on forces, you could try building FE models.
Good luck.
following links may help you
http://www.sciencedirect.com/science/article/pii/S221509861630578X/pdfft?md5=e746752fe0c704d48b5e862f769af1b1&pid=1-s2.0-S221509861630578X-main.pdf
http://www.ijsr.net/archive/v3i12/U1VCMTQxMDcw
Good luck
The tool nose radius is the angle formed by the point of the tool. This radius may be large for strength, or sharp for fine radius turning. A sharp edge is weak and fractures easily. The tool nose radius value influences the resulted surface finish.
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