By Heather Schultz, Creative Marketing Director ; Co-Author Stacy Cramer, Project Manager, Sharpe Products
Designing cost effective bends for your tube bending projects can be more involved then it may appear.
The cost in manufacturing a pipe or tube bend is directly affected by the amount of labor and tooling needed to produce your parts. In order to have the most cost efficient tube bends, the following are some key factors to consider.
1.) In traditional mandrel pipe and tube bending, a bend die that is built for a specific radius is required to create a bend. These bend dies can range in cost from $2,000 up to $10,000 depending on your pipe and tube size and the radius size. For high volume jobs the cost of the bend die may not be an issue, but for small runs it may be critical. It is possible to avoid these large tooling costs in cases where there is flexibility in the radius. Consulting with your tube bending house to see which radii bend dies they own and then choosing one of these radii to design your bend will save on tooling costs and lead time.
2.) In addition to choosing a die that already exists selecting a radii that is greater than 1-1/2 times the tube diameter will result in a cost effective bent part because center line radii tighter than 1-1/2 times the tube diameter will be more labor intensive and will have increased part cost. For instance a 4" O.D. tube bent on a 6" centerline radius (C.L.R.), which is 1-1/2 times the 4" diameter, is less labor intensive than 4" O.D. tighter bends such as ones that are between a 4" and 6" C.L.R.
3.) Typical pipe and tube bending processes with parts that have more than one bend require a straight length between the bends. Standard tooling can accommodate parts that allow a distance between bends of at least 3 times the tube diameter. Parts that have a distance less than 3 times the diameter are possible to produce, but may require special tooling which in turn increases tooling charges. An exception to this rule exists with a different bending technology, the Nissin tube bender. This technology applies to 1-1/4” O.D. and smaller bent on a radius that is 3 times the diameter.
4.) When designing a part there can be a tendency to be safe with dimensional tolerances when specifying your needs, but for cost efficiency it best to keep them only as tight as necessary. Specifying tighter tolerances will make the project more labor intensive and possibly increase your costs. Again, consulting with your bending house to see what bending tolerances can be held while meeting your requirements and without unnecessarily increasing your costs will be beneficial to the design and manufacturing phases of your bent tube project(s).
5.) Many customers tend to use a thinner wall for their projects to reduce material costs. However, thinner wall tubing may require more labor to bend….(as in some instance it may not be able to hold the roundness of the tube as it is bent and result in ripples or wrinkling in the bend). In some cases the additional labor costs outweigh the material savings therefore it may or may not be beneficial to use a thinner wall material.
The above tips are only a few things to consider when designing your mandrel bent pipe or tube product. It is always best to consult with your tube bending service provider to verify the specifications that you need to meet your project needs while yet making a cost effective part.
Heather Schultz is the Creative Marketing Director at Sharpe Products and Stacy Cramer is the Project Manager at Sharpe Products, located in New Berlin, WI. Sharpe Products is a leader in the custom pipe bending and tube bending industry. For more information on tube bending, visit http://www.sharpeproducts.com.