The Link Between Manufacturing and Parts Design

Technical factors for project consideration

Designing products with components that require custom tube or pipe forming can be more involved than it may initially appear. Factors such as tooling, materials and labor play a role in the approach to bending and associated services. Here are the details to take into consideration:

  1. Bend die: Known as the primary tooling, a bend die is required for pipe and tube forming, along with a clamp die, pressure die, mandrel and wiper. Most suppliers will have a stable of tooling to choose from; however, in some cases, tooling may need to be customized. This upfront work typically results in faster, more-efficient run-times. Here is an example of our available bend dies.
  2. Radius: As a general rule the tightest achievable center line radius is one times the pipe or tube diameter. Whenever possible, try to choose a center line radius of one-and-a-half times or greater than the tube diameter to save labor costs. Review our current tooling list to see the options available.
  3. Multiple bends: Parts that have more than one bend normally require a straight length between the bends for clamping. Standard tooling can accommodate a distance between bends of at least three times the tube diameter. Shorter clamp areas of two times tube diameter can be achieved, but may result in cosmetic marking from clamp modifications. Parts with a short length between bends may be good candidates for freeform bending.
  4. Tolerances: When designing a part there can be a tendency to be safe with dimensional tolerances, but for cost efficiency it can be helpful to keep them only as tight as necessary as tighter tolerances may add labor. Information on which tolerances must be met should be included in your project scope.
  5. Wall thickness: Some specs call out thinner wall tube or pipe to manage material costs. However, a thinner wall may require more labor to bend, using a mandrel and wiper to hold the shape and consistency of the tube through the bend and eliminate the chance of wrinkling. In some cases, these added labor costs may outweigh the material savings.

Although tube bending machine technology has progressed significantly over the years, many of the variables remain the same. These include the O.D. and wall thickness of the pipe or tube, the geometry of the designed part (simple or complex bends), and the time and labor that may be required.

Having a basic understanding of what is involved in the bending process, and consulting with your supplier will help support the design process and inform project timelines and costs.

This blog was authored by Randy Krickeberg, Plant Manager, Sharpe Products. Randy can be reached at