Questions about machining tolerance and time
Questions about machining tolerance and time
(OP)
Hi i am trying to figure out what cutting machines can do in tolerance and time, so that i get a better felling for the cost and to sort out some confusion
1.In an CNC machine are there any difference between the output tolerance between making a surface of 500x500 flat and the drilling of four holes 500x500 from each outer.
2. If i am going to make a surface of 1000x1000 mm^2 flat, who much in time does in vary between the following planarity tolerances, 1 0,1 0,01 in a feature control frame
Thank you in advance





RE: Questions about machining tolerance and time
On the first question, yes I'd expect a significant time different between machining a surface flat over 500*500mm and drilling holes in each corner. Of course you don't say how flat, what surface finish, how thick material/how deep holes, what size holes, what material etc.
On the second question, you may find that for the tighter tolerances you may need to go to a different process. Again you don't give material information, surface finish etc.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Questions about machining tolerance and time
It also may be that desired surface roughness will actually affect your cycle time more than tolerance, because it will require slower feed rate.
Just a thought.
RE: Questions about machining tolerance and time
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Questions about machining tolerance and time
RE: Questions about machining tolerance and time
For general machining tips there have been a few posts over time, I suggest a site search may turn up something. I got these results as the first few hits using site search.
thread404-163892: Machining Parts - What school didn't teach me?!
thread404-278305: More Machining/Design Tips
thread1103-197339: Machining tips
http://www.eng-tips.com/viewthread.cfm?qid=284781
There have been others, some relating to specific materials/processes such as sheet metal but my search kung-fu is week today for some reason!
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Questions about machining tolerance and time
For drilling, you will be moving the head to 4 points, so the distance calculation is easy.
For milling the surface, you need to account for the size of the milling cutter. In order to do 500x500, you would need a 250 diameter cuter to do it in 2 passes, but the travel distance is only 250 for the stepover, instead of the 500 for the hole distance stepover.
As Kenat pointed out, drilling holes use a rapid feed between points and milling speed has other factors to consider: material, cutter material, rigidity of the workpiece, surface finish, etc.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: Questions about machining tolerance and time
Doh.
More realistically/typically if using say a 25mm cutter then yeah you're looking at 20 or so passes simplistically so 5X the traveled distance for just the corner drilling.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Questions about machining tolerance and time
Realistically, any cutter over 100-125mm in diameter is hard to load in a CNC machine with tool changer. A 500mm+ diameter cutter would require manual tool change.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: Questions about machining tolerance and time
This is not really a dimension and tolerance question. You would be better off asking this in forum281: Machines & Machining engineering.
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JHG