What are packaging tapes

Interesting facts about strapping & strapping

A) The elasticity (working range)
Strapping lives from the tension applied to the package. It is essential to maintain this belt tension over the entire transport route! The elasticity of a tape is decisive for this. This means the expansion and, above all, the back expansion of the band. High-quality plastic straps made of PP or PET have a higher elasticity in terms of expandability than steel strapping, but benefit particularly from their high elasticity that steel straps do not have (close to zero). A very good strapping band has both very good elasticity for expansion (important for tensioning the band) and very good elasticity for rebound. High-quality PET straps have an elastic recovery of approx. 5 - 6% based on their maximum breaking load. This is important so that the strap does not slacken or "wear out" in the event of impacts / shock loads or other changes in the volume or shape of the packaged goods caused by dynamic or static loads and the load securing is thus lost.

Tension stability of PET compared to steel tape

B) The split and splice resistance
Straps must have good split and splice resistance so that they do not tear during processing or in use, thereby endangering the load securing. Good split and splice resistance is achieved through the use of high-quality additives and by applying a flame to the strip during production after the stretching process. An optional rolling of the strapping after the flame treatment increases the splitting and splicing ability even more.

C) The breaking load and strength
The breaking load indicates the tensile strength of the tape in relation to its dimensions. The strength, on the other hand, always relates to the strength of the raw material used and is specified in N / mm².

To determine the correct belt dimension, proceed as follows:

Weight of the package to be strapped x 2.5 (safety factor)
(Number of parallel bands x 2) x 0.8 (clasp)
= Breaking load per band in kg x 9.81 = breaking load band in Newtons

This formula is valid for calculating the breaking load of steel strip. If the breaking load of plastic tape is to be determined, the result must be divided by two again.

D) The fastener strength

The clasp is the weakest link in the strapping - like a chain. The total breaking load of a strapping can therefore only be as strong as the breaking load of the closure.

Average breaking loads of the different types of lock:

Steel beltSteel beltPP tapePP tapePET tape
Sleeve lockPunch lockThermal closureFriction weld closureFriction weld closure
approx. 85%approx 80%approx. 50 %approx. 60%>80 %

E) The lubricity

This is necessary so that the strapping can be stretched around the packaged goods well and, if possible, without damaging friction. In addition, good and even sliding properties ensure good and secure closure of plastic straps with the friction welding process (vibro-closure process), which is used when battery strapping tools are used. Good sliding properties are achieved by adding appropriate additives (PP tapes) or by waxing the surfaces (PET tapes). Belts with waffled surfaces have poorer sliding properties and the belt tension on the packaged goods is lost due to waffled surfaces.

F) The dimensional accuracy
A constant dimensional accuracy over the entire roll is important so that the processing of tapes with machines and devices works well and no malfunctions or machine problems occur. A very good dimensional accuracy is achieved with steel strips and plastic strips that are manufactured using the sheet extrusion process thanks to the precision of the cutter bar. In the case of plastic straps that are manufactured in a single extrusion process, the quality of the extrusion nozzles and the continuity of the extrusion volume conveyed are decisive.