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Joint Efficiency Calculator
Joint Efficiency Calculator
Published tensile force describes the strap. What reaches your load is set by the joint. Enter a published force and pick one of the four measured joints below to see what survives at that joint.
Calculate Joint Load
Results appear here. Nothing is submitted anywhere.
What this calculator does not do
- It does not produce a working load limit, a pallet rating or a strap count.
- It does not model your closure. It applies a percentage measured on someone else’s specimen to a force you typed in.
- It ignores applied tension, edge condition, settlement and route hazards, all of which change the outcome on a real pack.
- Only a controlled trial on your own load closes the question. That is what the second field below is for, once you have a measured result.
Where these four percentages come from
Every percentage in the selector is a measured row from one published source: the joint strength comparison in US Patent 5,772,944, Method of manufacturing plastic strap, assigned to Samuel Manu-Tech Inc and granted 30 June 1998.
- The assignee is a strapping manufacturer, and the table was filed in support of its own surface-treatment claim, so read it as evidence from an interested party rather than as a neutral benchmark.
- The specimens came from one manufacturing process in 1998. They are not a property of polyester strapping as a class and they are not UD Packaging product data.
- No percentage here was estimated, averaged or carried over from a supplier catalogue. If a joint you care about is not in that table, this calculator has nothing to say about it.
| Strap and joint | Rated force | Break load | Held at the joint |
|---|---|---|---|
| Surface-treated polyester, hot knife weld | 130 KSI | 1950 lbs | 85 % — 1660 lbs |
| Conventional polyester, hot knife weld | 65 KSI | 1300 lbs | 80 % — 1040 lbs |
| High tensile steel, sealless joint | 140 KSI | 2100 lbs | 76 % — 1600 lbs |
| Untreated high strength polyester, hot knife weld | 145 KSI | 2175 lbs | 32 % — 700 lbs |
Why the ranking can invert
Read the table by rated force and the untreated 145 KSI polyester leads it. Read the same table by what survives at the joint and it comes last, behind a strap rated 15 KSI lower that carries more than twice the usable load.
Qualify the joint before you buy a heavier coil.
