Tensile Strength Vs. Break Strength
Tensile Strength vs. Break Strength
Whether you've worked with strapping for many years or are a novice user, you've almost certainly heard about strapping tensile strength and strapping break strength. These two factors are key to understanding how your strapping works and knowing what grade of the strap to choose to keep your products secure and your pallets stable. Knowing how these measurements are taken and the differences between them is a necessary skill when it comes to successful strapping and we can help you with just that. Below, you'll find a comprehensive guide to the different types of strength and how they fit into your packaging plans.
Break Strength In Strapping
Understanding the break strength of your strap is actually pretty straightforward, as it is the measurement of how much tension can be placed on the strapping before it breaks. Most often, it is recorded in pounds, though you may occasionally see it measured in Newtons. A certain piece of strapping break strength is determined by a cross-section of the strap, meaning the width and gauge of the strapping itself. As the width and gauge of the strap get larger, the break strength will increase. Different types of strapping polyester, polypropylene, and steel each come with different break strengths as well.
How Is Break Strength Used?
In the professional packaging industry, break strength helps workers know how much tension they can place onto a strap before it breaks. This means a strapping professional will be able to more easily measure the working range of their strapping, which well discuss in more depth in just a bit.
Tensile Strength In Strapping
A piece of strapping tensile strength relates specifically to the type of material it is made out of. It is used to compare the strengths of different types of strapping without needing to refer back to the actual piece of strap itself. To determine tensile strength, you first need to know the strap's break strength. All you need to do is divide that break strength by the cross section (the width and gauge) of the strapping. The final number is recorded in psi or pounds per square inch.Here's a quick example: Break Strength: 1,000 lbs. Cross Section: 1 by .025 -> 1 x .025 = .025 Tensile Strength: 1,000 .025 = 40,000 psi
What Does Working Range Mean?
Despite having a high tensile strength or impressive break strength, strapping can be limited in capability by its working range, which limits the amount of actual tension that is applied when it is being placed onto a load. This tension is referred to as applied tension and is measured in pounds. Most often, it is a much smaller number than the strap's break strength and will differ between the various types of strapping material. In practice, the working range of a particular variety of strapping is what determines how tight an operator can apply that strapping and at what level of tightness the strap will perform at its peak. We consider that peak to be a sweet spot with some elongation but not so much that the strap will never recover. The actual strapping material and size are not the only factor that goes into determining a working range. Other factors include the type of seals you use, what kind of joints are created, the strapping tools you utilize, and the package itself. For example, some strapping tools can only apply so much tension, which lowers your working range, while others offer high amounts of tension, meaning you have to be careful not to stretch your strap past its breaking point of elongation. Additionally, strapping can only meet a break strength as high as the break strength of the joint seals. If a seal has less break strength than the strap, the seal's limit will be the top of the strap's working range. Something else to keep in mind is that even if you apply a strap as tight as you possibly can, you may end up damaging any fragile products underneath, which means the working range will be lower for straps that secure delicate loads.
Dont Forget
Before we wrap up this guide to strapping tensile strength, break strength, and working ranges, there are a few key items to keep in mind. Always remember that strapping failure is more likely to be the fault of the application instead of the material itself. Furthermore, while steel strapping offers much better tensile strength than its nearest plastic counterpart, it is more dangerous to use and will cost more upfront. Finally, when you increase the width and gauge of a piece of low-tensile strapping, you'll improve your break strength to an amount higher than a piece of strapping with high-tensile strength.
