Let’s face it, bending a thin, little, hollow tube that’s smaller than a 1/16” diameter takes virtually no effort at all. The rub comes when you still want to be able to pass a gas or a liquid through that tube after it is bent.
Here’s the problem: Even though stainless steel hypodermic tubing is a full hard tube when you get down into the very small ODs like 0.013”- .032,” the tubes do not have enough tensile strength to remain at the radius they are formed. They spring back and you wind up having to bend them at a much smaller radius than your finished radius, thereby compounding your problems.
So, to start mitigating this problem, you need to address these three questions. How big? How steep? How long?
How big (or small) is the OD and ID of the tube I need to bend? Generally speaking, the larger the diameter, the easier the tube is to bend. However, the thinner the wall, the more likely the tube wall is to collapse while being bent.
How steep of an angle do I need to bend? Obviously the greater the angle of bend, the more difficulty you will have in maintaining the wall integrity. We recently did a job for a customer who needed a 135° bend (in essence a V shape.) In this job, the issue was not how to maintain the tube’s ID, but how to minimize and control the collapse of the tube walls during the bending process.
How long can the radius be? The compression/tension forces on the tube walls are exponentially reduced as the radius increases. So your success rate will significantly increase as the radius increases.
So, before you design your next project incorporating some little innocuous bent hypodermic tubing consider these three very inter-related issues, and if there’s anything we can do to assist your process, please contact us: firstname.lastname@example.org.