Surface Finish Defects on Mould (Banding / Waviness) – PowerMill Raster Finishing + Point Distribution

[anto_joseph4HH2K]

I am experiencing consistent surface finish issues when machining a mould surface using PowerMill finishing toolpaths. The issue appears as visible banding and wavy patterns across the machined surface, particularly noticeable under light reflection.

-Can Redistribute output type introduce surface deviation significant enough to cause visible banding on mould-quality surfaces?

-Is Point Separation Angle (1°) known to create non-uniform tool motion leading to ripple artefacts?

-Recommended tolerance and mesh factor values for high-quality mould finishing?

-Are raster strategies inherently unsuitable for this type of surface compared to morph / spiral / flowline?

[iamcdn79]

turn on the 'point separation distance' to give it more points and play with the values. Start at a high number and then bring it down if it doesn't improve

[rich11]

With Redistribute i found the tolerance factor need to be really low, the mesh is ok at 0.1 or lower but the factor needs to be 0.01 or less

[icse]

Isn't the factor relative to the tolerance? 0.03 seems very low, what's your tolerance?

[rafael.sansao]

Hello,

Your tolerance factor and mesh factor values are VERY low.

If you are using a toolpath tolerance of 0.01 mm, and your tolerance factor is set to 0.03, PowerMill is effectively calculating with an internal value around 0.0003 mm. That is unnecessarily small and can actually create unstable point distribution and visible surface artefacts.

I would recommend starting with:

Toolpath tolerance: 0.005 ~ 0.01 mm (0.005 mm should already produce an excellent mould finish)
Point Distribution: Redistribute
Tolerance Factor: 0.3
Mesh Factor: 0.2
Leave all other point distribution options disabled

This settings should generate a very good surface finish.

Also keep in mind that strategies such as Parametric Offset and 3D Offset can become distorted during calculation because of the boundary definition. Make sure the boundary itself is not introducing the issue.

A good way to verify this:
If the boundary is the source of the problem, you should be able to visually see the waviness directly in the toolpath when displaying the toolpath points.

[rich11]

I no longer use it myself, I use tolerance and keep arcs, but turn off the arc support in the post. 

for finish, tolerance = 0.1 and mesh 0.1/0.05

I get a faster calc and less vertical noise

[anto_joseph4HH2K]

I tried tweaking all parameters including point distribution,tolerance and mesh, nothings improving the fisnish as shown, one thing i noticed is that the ripples goes away when i use a smaller ball nose,(6mm) and gets worse when i use a (16mm)

[navya_gelli]

Hi @anto_joseph4HH2K ,

I wanted to check in and see if you still needed assistance, or if you found a solution to your question already? Let us know if you need further assistance by providing an update or if you have found a solution, please share it with the community so other members who may have the same question could learn from your experience.
 

[anto_joseph4HH2K]

Hi,
I still havn't resolved the issue, I tried all suggestions from the community.I am still tweaking different parameters hoping to find a soluton

Cheers

Anto

[nguyenthinhvt95]

This is my favorite setting, and the result is perfect. You can give it a try.

P.S. The calculation time and collision checking take a bit longer, but the surface finish is excellent.

 

[rich11]

update

chatting with AI.

I did some tests and I like the results, redistribute at 0.5, Tol at 0.005 and mesh at 0.01.

Apparently mesh should be twice the TOL. 

[navya_gelli]

Hi @anto_joseph4HH2K,

Did the info from nguyenthinhvt95 and rich11 help answer your question?

If it did, it’d be great if you could click the "Accept Solution" button so others can easily find it too.

If you’re still needing more help, feel free to share an update here. The community will be happy to jump in with any next steps to help you get where you need to be.
 

[TK.421]

Why should mesh factor be twice the tolerance?

@navya_gelli please dont start spamming posts about solutions. if autodesk wants to be "helpful", give us new functionality. otherwise, please stay out of our way on here.

[rich11]

To be honest it is something the Copilot AI picked up on.

So far I have done three job with this setting, no issues yet, very small programmes in comparison, very stable z moves.

I have yet to try it on a larger job

[TK.421]

ok. i've always made it the same as my tolerance, but for no specific reason other than i thought it seemed like the right way to do it. 

i've got a 5axis cut that is doing the herky-jerky so i'll play with that too & see if it helps improve the motion any.

[rich11]

you thinking redistribute and the tolerance factor 0.5?

I might of had duff info when I started out, that the mesh of 0.1 is 10% of tolerance.

That made the tolerance of 0.1 with a mesh setting of 0.1 made the mesh 0.01 as an example.

[TK.421]

i know our heidenhain control likes points, so i made my tolerance factor .25 and the point separation distance .125 (inches), always using redistribute for that control.   my coworker told me to tighten that up even more, so now i cut those numbers in half & we'll see what that does.  I'll ask him when he gets in what the use is for mesh factor, if that would help or not in this case. 

[rich11]

Never had to use point separation distance.

On one programme I did with 0.5 tolerance factor I drew a circle on the tool path points to check cusp heights. I found all was good in this case inline with the tolerance.

For angled shut out work I will be testing 0.002 tolerance, mesh 0.004 and factor still 0.5 (small local progs normally)

I am assuming a factor of 0.25 is just increasing points/programme size and the start to stress some machines out at the moment.

I will no longer be using a tolerance factor of 0.1, after having drawn those points up.

good luck with your tests.

[TK.421]

let's compare notes after this. maybe @Sean570 can shed more light on this

[ahorwood]

This has been a very good, informative discussion.