Machining/milling time; cnc; routing

Replies to This Discussion

Permalink Reply by Hannes Löschke on December 12, 2013 at 9:21am

Depends on your mill, the complexity of your object, your tool and finally the way, you prepare the toolpaths.

Permalink Reply by Hannes Löschke on December 12, 2013 at 12:43pm

So as an approximate answer: 3hours...

Seriously, it all depends. Say, you have a simple, smooth curved NURBS Surface. Say you use a large tool diameter to move fast and chip away lots of material. With a 4 axis mill, you could get good results in one run, because the tool can be tilted normal to the surface.

With a 3 axis mill, you would at least need two perpendicular runs and probably two more runs with a smaller tool to get the surface quality you need. That's probably 5 to 6 times what the 4 axis mill took. Same Surface, same material, same tool.

Even if material an tool would allow for a speed of 2m/min, there are mills, that can move only 1m/min. Same problem, double the time.

Travelling speed also depends on the spindle RPM. Your tool and mill might allow for faster travel but would require more RPM, than your spindle can turn...

Permalink Reply by Hannes Löschke on December 13, 2013 at 2:36pm

Without knowing too much about machines and stuff, you should take your hands off milling or at least get in touch with someone with expierience for this particular machine.

You should generate your toolpaths first. Normally, the milling software will give you an approximation of the time needed to mill.

So this someone should also be able to estimate the overall price from your model.

Permalink Reply by Hannes Löschke on December 16, 2013 at 3:00am

Well, there is but not without knowing a bit about the machine and stuff. To get you started.

- You can estimate the routing depth as about 1 to 2 times the tool diameter.

- You will probably have some path overlap to reduce tool wear. 50% might be a good estimate.

- Most of the time, you will route in two steps (roughing for volume and finish for surface) both with different tools.

That will get you a rough length of the overall tool path. Add some more for tool positioning.

Now for the time factor:

Cutting speed (vc) for wood is about 300m/s. That's for a single tooth or blade throught the material.

You can calculate the optimal RPM by

n [RPM] = (vc [m/min] *1000) / (3.14 * Ød1 [mm])

the travelling speed can be estimated by

f [mm/min] = n * fz * z

with z = number of edges and fz depending on material and tool diameter (0.05 as an estimate)

There are some online calcualtion tools, that help you... still you will need a bit of knowledge about the technology to use them.