Jerky swarf machining

[Joppe]

We are currently experiencing some issues with 5-axis continous machining. The problem is that when machining some parts with swarf machining, the machine moves in a very jerky motion. This again gives a very rough surface. Anyone else experienced this ? The Machine is a Biesse Rover C6, 5-axis.

I've attached two pictures. The first picture shows a round flat table with a chamfer on the edge. I've added a swarf machining two this chamfer, linked to the lower and upper curve of the chamfer. This chamfer is machined flawlessly and very smooth.

In the second picture I've given the table a bend, so it is not flat anymore. This time the machining is very jerky and surface is really rough and uneven. Why so ?

When machining the chamfer on the flat table, the machine can "lock" the b-axis to a certain angle and only vary the c-axis as it goes around the table. In the table with the bend, the machine has to move both the b- and c-axis to be able to machine the chamfer. So to me there seems to be an issue when the machine has to use and continously adjust the b-axis ? Its almost like the machine makes a small stop in between every point, instead of moving smoothly from point/segment to the next point/segment. Is there a g-code smooth we can add to the PP ? Or do we have to do something with the curves or surfaces needed in this kind of machining ?

[Mark Oostveen]

I don't think you can correct this by changing your geometry. It does look good on the picture.

You need like you ask a "smooth" function in the machine or you might try to play around with some settings. Another option is to create the operation on curves in stead of the surface, but as said above, I won't give it mutch change based on what I see.

I don't know a smoot function in the Biesse myself. Not that experienced with these machines. Do you use BSolid or BieseWorks?

But there is the possibility that there are to many coordinates passing by the controler that it cannot keep up reading and processing, therefore the machine gets jerkey. This could be the diference between the two files as it has to move more axis as in the first example. Is the angle for the B-axis in the second examble in relation to the Z-axis the same all around the part or does it change?

You can try to reduce the number of coordinates genereted by increasing the tolerance in the swarf operation.

Succes

Mark

[Joppe]

Yeah, looks like there might be need of a smooth function. The operation i s actually created on curves. But it doesn't do much of a change creating the operation on the surface.

We use Biesseworks and TS. I've aked our reseller if we could have a limited copy of BSolid to play with, but that wasn't possible. BSolid looks interesting though. Have you tried/used it ?

Hmm, havent thought of "data overload". But I'm unsure if that's the case here. The machine is a fairly new (2011) Rover C. It should be able to handle this. I've done a lot of surface machining with very tight steps to create a smooth finish, and it works flawlessly. No problem at all despite the ISO file being pretty large. But you're thinking that the machine might have trouble operating all axes simultaniously - and this than gives an overload ? Not that it's having problem reading each line in the ISO file in the pace needed for the machining ?

The B-axis changes in small increments all around the table (pls see attached pic).

I've tried to play around with almost every possible setting available But not much of a difference. Adjusting the curve tolerance doesn't do anything at all unfortunately. Can't see any changes in the ISO and the machine behaves the same whether it is set to 1 or 0.005. The only thing that really makes a change is adjusting the "Maximum distance between points". It's normally set to 2mm, which works fine with the b-axis "locked". If i adjust it up to something like 4mm its a bigger gap between the "stops" but still a horrible surface on the bend table. If I adjust the "Maximum distance between points" down to 0.5mm for example the machine moves reeeaaally slow. Like it can't manage to get up to speed between each time it hits a new point and stops before starting again. Still a bad surface. And no good for the cutter. So annoying

Thanks for Your inputs and ideas ! Highly appreciated

[Mark Oostveen]

If you say that sweeping is fine. Can you find a smooth function the g-code of these operations?

I don't, know if bold is better. I guess it is not as we control the machine by g-code which is what bsolid in the background probably creates when programming something in bsolid.

Mark