Fabrication Tolerances for Dimensional Variance in Sheet Metal and Machined Parts
Our bending equipment consists of folders and press brakes. While both can achieve highly accurate bends, each type of equipment offers its own advantages.
Folders are especially best for repeatability - for higher-quantity jobs, folders are your best bet for achieving accurate bent parts over and over. The press brake, on the other hand, is more flexible and can bend certain parts that the folder just cannot, especially in small or one-off quantities.
Whichever equipment we use to bend your parts for you, there will be tolerances to consider. Bends (and their corresponding tolerances) either pertain to a controlled dimension, or an uncontrolled dimension.
Controlled Vs Uncontrolled Dimensions
Controlled dimensions refer to the length of the flange of any bend. Controlled dimension bend tolerances are standalone, and therefore do not need to be considered in relation to any other bend.
Uncontrolled dimensions, on the other hand, refer to the sections of the part where the bend originated from. Uncontrolled dimensions contain two different categories of tolerances:
1) All manufacturing tolerances used up to that point (such as laser-cutting tolerances, welding tolerances and more)
2) All bend tolerances for the entire part, added together
We call this an uncontrolled dimensions because there are additional tolerances to consider. All of those tolerances are added together, or put another way, they are stacked tolerances.
Please refer to the diagrams for more information.
|Bend angle||± 1 degree|
|Bend length||± 0.010" | 0.25mm|
|Press brake bend length||± 0.010" | 0.25mm Per bend for controlled dimension|
|Folder Bend Length||± 0.010" | 0.25mm Per bend for controlled dimension|