Q1 WHAT IS THE DIFFERENCE BETWEEN TUBE AND PIPE?

Often today, you may not have actual part prints available to confirm material size and dimensions. A measuring device such as vernier calipers can be used to gauge the material's

outside diameter (O.D.) and inside diameter (I.D.), which will enable you to confirm necessary dimensions and make simple drawings.

Knowing the material’s true dimensions is key to selecting the proper machine and tooling for your application. Pipe sizes are measured by I.D., with wall thickness referred to in

terms of schedule. Tube sizes are based on O.D., and wall thickness is referred to in gauge sizes.

Q2 WHY IS MATERIAL SO IMPORTANT?

When purchasing tube for your job, remember that the cheapest isn’t always the best. Bending tube or pipe of poor quality material often leads to poor-quality bends, higher rates

of scrap, and possible breakage. Even the best machinery and tooling won’t overcome poor-quality tube material.

Material grade affects the tooling selection and composition; make sure the tooling is supplied to your material specifications so it doesn’t conflict with the material to be bent.

As an example, stainless tube can conflict with a steel counter bend die.

When making a decision about material for your application, consider application strength requirements, appearance and quality, and centerline radius specifications. Ask your

steel supplier for the material specification to ensure the material is appropriate for bending.

Q3 WHAT IS THE MAXIMUM DEGREE OF BEND?

This may sound simple; however, it is not if you are not given prints and are asked to reproduce parts from sample pieces.

Rotary draw bending tooling usually is designed to accept a maximum bend angle of 180 degrees. When selecting bending machinery for your application, be sure the machine

program or system allows for slight overbending to compensate for springback during the bend cycle. Selecting a bending machine with a programmable bend angle setting can

provide high bend accuracy and ease of use.

Degree of bend also affects bend quality. When working with a new material, try making two test bends—one at 45 degrees and one at 180 degrees. You may see slightly different

results in the workpiece, because greater bend angles produce more wall thinning and deformation in the material.

Q4 WHICH BENDER IS RIGHT FOR MY SHOP?

Tough question, and maybe most important. No one bender is right for everyone. When selecting a bending machine, consider all of the points in this article before purchasing one.

Also be sure to consider what capacity you might require in the future. Purchasing an inexpensive machine today could prove more costly in the future as other applications arise.

Other considerations include machine versatility, features, tooling, availability of parts, and qualified local and regional support.

Decoding Bend Terms

CLR – centerline radius. Distance from the center of the forming die to centerline of the material

DOB – degree of bend. Number of degrees required in a bend

Sch. – Schedule, or wall thickness of pipe

Ga. – Gauge, or wall thickness of tube

O.D. – outside diameter. Tube is measured here

I.D. – inside diameter. Pipe is measured here

Q5 HOW TO CHOOSE THE PIPE/TUBE BENDING MACHINE?

You have to inform us following details:

- Max. outside diameter

- Wall thickness range

- Bending radius (CLR)

- The pipe material

- The drawings if possible