CNC Bending Service

CNC bending is a process where sheet metal is bent to an angle using, typically a V shaped punch and die. The sheet is placed between the punch and die which presses down on the sheet. This method of bending provides a low cost method to product 3D shapes from 2D sheets. CNC bending is a suitable for processing most ductile metals and primarily for sheet metal designs with one or more bends. Just a few examples of are brackets, enclosures, cams, chassis, etc. There is generally no special tooling required, with the exception of intricate designs and special bends.

Cost Reduction Tips

  • Reduce the number of bends in design.
  • Design parts to pack efficiently. For example, if designing a large box consider making the sides of the box separate with bolted flanges.
  • Avoid complex bend combinations.
  • Avoid the cost of bending by adding slots in place of the bends and then bend manually. Such parts also have lower shipping costs and take less storage space. (To create the slots use a few thin rectangular cutouts in place of each bend line.)
  • Avoid odd angles.
  • Provide straight edges that are parallel to the bend.

CNC Bending Design Considerations

  • The minimum distance from the bend to the edge should be at least 4 times the material thickness plus the bending radius.
  • Holes or slots should be located a minimum of 3 stock thickness plus the bend radius. If it is necessary to have holes closer, then the hole or slot should be extended beyond the bend line.
  • Allow for variation in bend position, radius and angle.

Slip roll bending

eMachineShop can provide bends using a slip roll with the following specifications:

  • Rolls are 24″
  • Width * Thickness ^ 2 must not exceed:
    • 0.10 for aluminum 5052
    • 0.07 for aluminum 6061
    • 0.15 for brass
    • 0.05 for steel
  • Radius > 1.5″
  • Angle 1 to 360 degrees

To specify slip rolling use comments to machinist to indicate the bend region, radius and curvature direction (e.g. “Slip roll bend from A to B, radius 3 in, concave”). 

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