For a general overview of tube bending types, check out this article.
1. Choosing the Right Tube Bending Services for Your Project
Tube bending is not one-size-fits-all. Different types of bending will work better for projects with different tolerances, requirements, and order sizes. Choosing a vendor that offers the most appropriate form of bending for your project will save cost and grief in the long run.
There are four basic types of bending: compression, roll, freeform, and rotary draw. All have their pros and cons.
Compression bending is best for projects that:
-Require low cost, high-speed production
-Do not require a tight centerline radius (CLR)
-Do not require perfect roundness or nice aesthetics
-Make a symmetrical, simple part
Roll bending is best for:
-Products with large radii
Freeform bending fits projects that:
-Are complex and have multiple radii
-Have large radii
-Have thin walls
-Want to cut down on tooling costs
-Do not need mandrels
-Require secondary operations or alterations
-Need to be aesthetically pleasing
-The cost does not matter (freeform bending is costly)
Rotary draw bending is best for:
-Extremely tight radii
-Projects with tight tolerances and high accuracy requirements
-Making smooth, attractive bends
-Projects with no large radii bends
Smooth, tight bends with rotary draw bending
If your current vendor cannot provide the most appropriate type of bending for your project, consider moving your project to a different manufacturer for that project. If you require continued tube bending services, you may need to switch vendors altogether.
As with all forms of manufacturing, setup is an unfortunate but necessary cost. There are two main factors that will affect setup costs:
-How your manufacturer handles the setup of their machinery
-The size & scope of your project
There are steps a manufacturer can take (mostly regarding lean manufacturing) that can cut down on setup time significantly. However, if your project is complex or you're running a small order, high setup costs may be unavoidable.
Employees need to eat! The more hands-on work required for your project, the higher your costs will be. A manufacturer can control the cost of manpower through automation and streamlined processes.
Again, sometimes labor costs are unavoidable. Complex projects may require more hands-on work to ensure quality or do multiple tooling changeovers.
There are things you can do in the design process that can lower your tube bending costs. These include:
-Loosening your tolerances wherever possible
-Increasing wall thickness (thicker tubes use more material, but require less manpower to get a nice bend)
-Designing for straight sections between bends
-Optimize hole, tab, etc. locations (leave enough space between the fabrication and the bend so no warping or thinning occurs)
If you're struggling with the design, some manufacturers have in-house engineers who are very familiar with optimizing designs for these processes. Ask your manufacturer about their design services for more info.
The amount of tooling you need directly affects tube bending costs. Rotary draw and mandrel bending is the most expensive in regards to tooling - it requires mandrels, bend dies, clamp dies, pressure dies, and other machining components.
On the other hand, compression bending requires little to no tooling (though it can be more costly if your project isn't a good fit).
You can reduce tooling costs by eliminating the need for disposable tooling like mandrels and wiper dies. These tools wear down quickly and are the biggest contributors to high tooling costs.
Another way to save on tooling is to work together with your manufacturer to design a product that fits with dies they already have. Designing and ordering new tools and dies can quickly drive up project costs. If your project doesn't absolutely need unique tooling, this is a great way to save money.
Ask Your Manufacturer
You might be surprised how much guidance your manufacturer is willing to provide regarding tube bending costs. The problem is people don't ask about it. Whether you need help with design or other optimization, your manufacturer is probably happy to help.