Taking on the challenge of sheet metal variations. Press brake mechanical designs, control technologies and CNC software have come a long way in recent years. Modern press brakes are designed to be extremely accurate and with excellent repeatability, so they are more than capable of producing consistent results. However, no matter how capable a machine is at performing bending tasks, the final results are always subjected to variations in sheet metal quality, thickness and grain direction that can lead to inconsistent bend angles, wasted material and lost production time. Reliable and consistent production can be hampered by variations in material thickness when parts are cut from sheets that come from different batches. When blank parts are cut from multiple sheet stocks, there is no guarantee that the material will be consistent from one part to the next. Even minor variations in sheet thickness could require corrections to be made in the program to compensate for this.
Material grain direction is another issue that can cause problems with inconsistent spring back angles. There can be variations in spring-back due to changes in material grain direction as the part is turned and rotated between bends or there may be an inconsistency in the grain direction from one part to the next in a batch of parts. This could be due to the orientation of the blanks when they were cut from a single sheet or if the blanks are cut from different stock.
The normal process for press brake operators is to setup the machine and tooling for a new bending job, run a few test parts, then manually check the results. Unless all conditions are perfect, the operator needs to spend time making manual corrections for each step in the program, then run a few extra parts to make sure the angles are correct and within tolerance. Of course, all this takes time before production is up and running, not to mention wasted blanks. Even while parts are being processed, it is usually necessary to manually check each part or a sample of parts from a large batch to ensure angle tolerances and consistency are maintained. To aid the bending process, there are many different forms of angle measuring methods available to machine operators, from manual measurement using a hand-held protractor, to laser-based projection systems and mechanical contact devices. However, having the ability to automatically measure bend angles and use the information to control the bending process can prove invaluable.
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PRESS BRAKE BUYER’S GUIDE
