Is 0% scrap possible when mating parts using a plate laser?

[KegOBear]

To simplify this question, let's assume we have a square shaped part.

2" x 2" x 0.25

This part will be welded on all 4 sides, so the edge quality is of little importance.

The software we use is requiring a gap between parts. The machine has sensors that supposedly will "perfectly" square up the program with how the sheet is placed (meaning if its off square, it compensates) and I know there may be slight cutting issues but 0 scrap on a non-critical part and the "going over the edge part" may be questionable due to the autofocus of the head but... it seems possible in my head.

Is it possible to cut an entire sheet without a gap between parts and where the laser will cut off the edge of the sheet?

 

[EdStainless]

If you have enough slop in the system that you can weld directly on the as-laser-cut edges then I don't see why you would need a web between parts.
But you will need to cut a row at a time so that the machine can re-zero on the cut edge for each pass.
Otherwise you will get some size creep.

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[hendersdc]

It has been a while since I programed a laser cut part but could it be due to needing to account for the width of the laser? If 2 parts shared a boundary you would be cutting into one part or the other and the SW may not like that. Could also have something to do with pierce locations or tabs if those are present.

Could you cut all the interior features on the laser and then finish on a shear to separate the parts from the sheet? That might be more work than the small amount of material savings is worth.

 

[KegOBear]

Thank you both! You are correct, the tolerances on these parts are pretty generous. Also, in addition to the material savings, it should cut down on the time in the laser since it would be sharing edges.

I was thinking of manually programming these since the SW is not cooperating. I would love to try and just see what happens but a couple people in management, who say it is impossible, won't take the time to test it out. This is our highest running part (sometime requiring days to cut the order) and it is incredibly simple.

My biggest unknows are the lead ins to the other parts, what order to cut the parts, where to start and where to finish... Do I cut all the vertical then come back and cut the horizontal? But at some point the sheet loses integrity.

Oh man... It may be more trouble than its worth LOL but I hope someone out there has done this already and can say, "Oh you dummy, its simple, just......."

Thanks again!

 

[EdStainless]

How many of these do you use?
It sounds like you are using laser because you have it.
I would start at one corner, index over, cut up and then out making one piece.
And then repeating the up and over across the plate.

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[KegOBear]

That is hilarious you'd say that. "It sounds like you are using laser because you have it."

We bought the laser partially based on saying this would save us money cutting these. Prior to this we bought 2" flat stock bars, stacked the bars 4 high, and using a saw cut them 4 at a time.

There are some imaginary numbers someone threw at this to "prove" we are saving money, but I can't imagine in my wildest dreams cutting these on a laser could save us money. (Scrap, Gas, Electricity, the cost of the machine...)

It drives me nuts seeing the scrap and time we waist on these so yes, you are right...

At any rate, I hope to try that. I've been trying to find a video of someone else doing this to kind of prove its possible but its not the easiest thing in the world to search for on the interwebuals...

 

[hendersdc]

Are there any holes or other features on the parts or are these really just solid squares? If so, I would make these on a shear out of sheet or bar stock, probably faster and cheaper than the laser or the saw.

 

[KegOBear]

Nope...
Basically, the top 3rd of a stop-sign in shape.
Two 45º's at 6" overall length.

 

[IRstuff]

In principle, there should be very little additional wastage compared to sawing, since the kerfs shouldn't be worse. Ostensibly, repeatability and accuracy from essentially a laser CNC should minimize wastage.

TTFN (ta ta for now)
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[hendersdc]

You may be able to trick the SW into cutting the parts you want. If you determine the minimum web thickness that it will allow you to have you could create dummy parts that are smaller by that amount minus the beam width. You would also need to tell the SW not to cut one side of the part, this could potentially be done by modifying the width of the tab if the SW won't allow you to cut only part of an outline. There could be some significant tabs between parts depending on what the minimum web is that would need to be snapped or cut later.

 

[KegOBear]

Thank you everyone for your help! I am going to run a few tests and see what the best strategy is. It looks like I may make a subroutine for the farthest left and right parts and one for the parts in the middle. Then on the next row, do something similar but not cutting the bottom edge (as it will not be there). I'll have to wait and see how starting off basically in space will affect the quality of the cut from one part to the next.

 

[looslib]

The nesting software we used for our laser machines had an option for common-edge cutting where it would cut adjacent parts to use a single cut between the parts to get 2 part edges.

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