Bends
Bending is done using Press Brakes. Press Brakes normally have a capacity of 20 to 200 tons to accommodate stock from 1m to 4.5m (3 feet to 15 feet). Larger and smaller presses are used for specialized applications. Programmable back gages, and multiple die sets available currently can make for a very economical process.
Air Bending is done with the punch touching the work piece and the work piece, not bottoming in the lower cavity. This is called air bending. As the punch is released, the work piece ends up with less bend than that on the punch (greater included angle). This is called spring-back. The amount of spring back depends on the material, thickness, grain and temper. The spring back usually ranges from 5 to 10 degrees. Usually the same angle is used in both the punch and the die to minimize setup time. The inner radius of the bend is the same as the radius on the punch.
Bottoming or Coining is the bending process where the punch and the work piece bottom on the die. This makes for a controlled angle with very little spring back. The tonnage required on this type of press is more than in air bending. The inner radius of the work piece should be a minimum of 1 material thickness in the case of bottoming.
The time here is based on the part size and standard times. The data came from a MTI Engineer experienced in FAB processes and has performed many time studies in this area of work.
User Input
1. Select "Gage Number"
The thickness of the sheet metal is called its gage. The gage of sheet metal ranges from 36 gage to 3 gage. The higher the gage, the thinner the metal is. If you don't know the gage number, select 16 (.0598) from the list for now. The actual decimal size will appear on the next line. You can then go back and reselect until the decimal size you want appears on the screen.
2. Enter "Length of Part".
3. Enter "Width of Part".
4. Enter the # of Bends".
Angle and Length not needed here.
5. The program will calculate the part weight for informational use only.
6. The Final "Time per Piece"
Will be for the total number of bends made to the part here.
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