Need Help!- How to mill out a large window in the middle of an alluminum alloy structure?

[diemetric]

Hi Guys,

I am looking for help form you. The problem is milling out a window at size of 1200X850mm in the middle of an alluminum alloy(6005A) structure with depth of 50~100mm, which is not solid structure. What's best tool path and milling cutter to do this efficiently? Is the Trochoidal a choice? But it seems wasting huge amount time on the additional circular movement. Can Truemill of SurfCAM be used ? oh, I forgot to mention that I hope mill the window to the all depth (50mm or 100mm) in one time?

Thanks.

[HuFlungDung]

I'll pass on the 'help forming me'

Does this part already have a rough opening which you have to clean up?

Trochoidal is a good choice when you've got limited horsepower, or extreme tool lengths that will not permit full diameter tool engagement. In cleaning out large solid sections with considerable depth is where you would see the greatest advantage.

Otherwise, profiling around a rough opening may be as efficient as anything.

[diemetric]

Thanks, HuFlungDung
This part has no a rough opening. Fast is my pursuing.
First operation is to mill out this opening with expect of the shortest cycle time and the longest tool life, second operation is to get good. The second is not difficult.

[HuFlungDung]

Because you are working with quite long tooling, a trochoidal style would probably work well. I'm thinking that you could mill about a 2" wide pocket around the inside of the window, and trochoidal will cut this quite quickly with a very deep tool engagement on each pass. Because the cutter engagement angle is less than 180 degrees, it should help reduce excessive noise due to vibration that would accompany plowing around with a full tool diameter trying to open up the cut.

[diemetric]

Hi, HuFlungDung,

Trochoidal mill works ok, but it wastes too much time on the circular movement.
Are there any other ways to give higher efficency? What's the Truemill of SurfCAM?

Thanks again

[diemetric]

oh, one more problem is the ribs somewhere was deflected when feedrate is higher. welcome any suggestion related to cutter parameters and materials, and cutting parameters.

thanks,

[HuFlungDung]

Are you reducing the whole opening to chips or are you cutting around making an island drop out? I would do the latter myself, but it might be more effective to use a bandsaw to remove the bulk of the piece if you have that facility.

I use OneCNC and for cutting narrow channels in high speed machining, it uses a high feed return in the non-cutting stage of each loop. So the cutting feed could be 150ipm and the high feed return could be set at max feed of your machine. The time that is lost in the looping motion is more than recouped by the additional depth of cut that is possible with the tool.

[TomB]

Without knowing the thickness of the skins and webs and whether the cuts are to be aligned with web corners as shown in the figure there are a lot of open questions. But given those unknowns, why not just drill four holes in the corners and then saw out the opening? Depending upon dimensions and the number to cut there seems to be a lot of ways to implement the sawing. If I had a lot to do I probably would build a tool to hold a sawsall vertically while it moves in a straight guide. If necessary for obtaining a smoth cut the movement could be motorized. Tool costs with sawsall blades are negligible.