Strapping Securely Products
Securing your products during transport is critical. Also, seal efficiency and the method of applying the strapping.
Nowadays, you can strap with both steel and non-metallic materials. Plus, they come with a specification stating a tensile strength at breaking point. While the strapping is applied to the product and is under tension, the weakest part of the strapping is at the joint or seal. That efficiency of this joint depends on the method used to seal the joining. The aforementioned process comes as a percentage of the overall strength of the strap.
How to seal steel and non-metallic strapping?
In the case of steel strapping two methods are used to achieve this joint. Furthermore, we find the usage of metal seals/clips or a seal-less joint. Machinery or tools apply the metal seals, where the seal is closed and crimped into the steel strapping. While in the case of a seal-less joint, the strapping needs to be under constant tension around the product for the seal to be effective. A “punch and die” mechanism seals the joint with the equipment used to apply the strap. Additionally, the sealing efficiency of the system largely depends on the tooling and the dimension of the metal seal. Overall seal efficiency is 60%, but 80% can come with right strapping equipment.
Concerning non-metallic strapping, the most commonly used in the packaging industry is Polypropylene and Polyester strapping. Certain strapping types also use two methods of sealing. Application of a metal seal and secondly sealing by melting the strap interface with pressure applied bonding the strap together.
What applications do you see metals seals used in?
All use of metal seals is frequently used in hand applications. Sealing efficiency at this level can be as low as 50% rising to 65%. There is a big usage for serrated seals which have a jagged surface. That rough surface is on the inside of the seal which reduces slippage.
Where metal seals are not used the joint can be achieved by heat. Heat comes either by a thermoelectrical heater plate or by rapid vibration. To conclude, vibration comes with the friction generating the heat to fuse the straps.
For strapping, where the gauge is up to 0.65mm the heater plate system is generally used with seal efficiency of minimum 55% can be achieved. Including a thicker strap, with the gauge in excess of 0.65mm, the friction system is used. The rapid vibration creates sufficient heat to melt the interface of the strap before pressure is applied to bond the strap together. Seal efficiency of minimum 65% can be achieved but a figure of 80% is achievable when properly maintained equipment is used.