Redback’s exclusive 5 Star Certification addresses critical performance factors for cord strapping. Our weave patterns, coatings, and buckle geometry work together to provide some of the highest repeatable performance in the industry. We demonstrated this in a previous video where the system strength of our 1830 lbs. strap with a 70% joint strength outperformed the system strengths of a leading competitors 2400 lbs. and 2700 lbs. Straps. And in our last video we showed our 1 ¼” 3300 lbs. strap with more than 80% joint strength outperforming the same leading competitor’s comparable system by almost 20%. So how is this possible?
Well, there is a difference between linear strength, joint strength, and system strength.
Linear strength is end to end strength and all straps can achieve a rated linear strength whether they are good strapping systems or not. They all look good on paper.
Joint strength on the other hand is end to end strength with a fastener in the middle. It incorporates the joint efficiency of the strap and the buckle which takes into consideration the dynamics of weave patterns, coating, and buckle geometry working together.
System strength is the strapping in loop form with the buckle and is also theoretically twice the joint strength. For example, a 1000 lbs. rated strap with an 800 lbs. or an 80% joint has a system strength of 1600 lbs. However, a 1000 lbs. rated strap with a 40% rated joint only has a system strength of 800 lbs. That’s a big difference in real performance, and when you have a 50% joint, linear strength and system strength are the same. Redback Composite Strapping Systems typically achieve 80% joint strengths and our woven strapping systems typically achieve 65% – 75% joints.
Tying a basic overhand knot achieves a 50% joint. As the ends are pulled tight the knot cuts down on itself so any strapping system with less than 50% joint is problematic because the joint is either slipping or functioning more like a cutter than a fastener. We see a lot of strapping systems like this in the market. We’ll show you some examples.
Using our ASTM calibrated test machine with competitor recommended buckles in single wraps pulled in loop form at 5” per minute. Here is competitor A slipping and breaking at the front of the buckle, at 35%, 38%, and 42%. Now I want to point out that its significant that most of the premature breaking we see occurs at the front leg of the buckle. So performing a double wrap, also known as a rail test, to lock the strap onto the back leg of the buckle does very little to improve performance. And testing the wrap on the front leg of the buckle is for the most part meaningless because you can’t tension a double wrap.
Here is competitor A slipping and breaking at the front of the buckle at 43%, slipping and breaking at the back of the buckle at 35%, and then slipping at the back of the buckle at 40% and ultimately breaking at the front of the buckle. And here is competitor B slipping at the front of the buckle at 44%, 46%, and 48%. Here is competitor C slipping and breaking at the front of the buckle at 53%, back in front at 53%, and front at 44%.
In our industry people tend to use a particular strap because its what they’ve always used, but few customers have sophisticated test equipment like we do. So they don’t necessarily know what performance they are getting. They just think it works. But in our experience if a strapping system has low joint strength its not working, and there are likely more efficient and superior system strength alternatives available at a lower cost.
If you would like us to test the strength of your strapping system or to learn more about Redback Strapping and our exclusive 5 star certification give us a call or check us out on the web at Redback.com.