Contimeta has an extensive range of products for strapping and bundling using plastic strap. A brief product summary follows below. Since the choice of the correct strap depends strongly on the implementation and equipment being used, Contimeta will gladly give specific advice.
This polypropylene strap was specifically developed for manual use. Available in widths of 12 to 16 mm and thicknesses of 0,55 mm to 0,8 mm in black and blue. Depending on the size, available in a boxed roll (without core) of 500 or 1000 meter or on a core of 406 mm with 2000 to 3000 meters per reel.
Especially for use on machinery, this high-quality polypropylene strap complies with the necessary high tolerance requirements. Depending on the implementation and machine, this strap is available on core size 150, 200, 280 and 406 mm. The width varies from 5 mm to 16 mm and the thickness from 0.3 mm to 0.9 mm. A wide variety of colors and running meters per reel are possible. Printed strap with your logo or other references is also possible.
PP Machine strap with low stretch
Specifically for goods where it is important that the strap remains around the package tightly, a strap with a low stretch is necessary. Low creep PP strap has a high breaking strength and a long stretch up to approximately 12%.
Hylastic or Hyperlastic strapping has an extremely high stretch (30 to 35%) and is used when strapping very small products or packages or when the package looses significant volume with the strapping, such as foam rubber products.
Contimeta's high-quality polyester strapping is characterized by high breaking strength in combination with a good recovering capacity and a high resistance against an impact load. Especially with heavy duty applications and long-term storage and/or transport this strap guarantees the highest possible stability of the load.
This strap consists of extruded polyester wires that are glued together giving this strap an extremely high breakage strength. The strap is often implemented in places where, for example, the strapping is subjected to excessive strain during transport. This strap is also very resistant against chemicals and UV-rays. This type of strap is applied manually with metal clasps.
This strap consists of woven polyester wires. The strap has a high breaking strength and is very supple, safe to use and moisture and water proof. The strap does not cut, can be re-used and can be used with or without clasps.
In order to fully understand the possibilities of plastic strapping, we have to do an in-depth study of the matter. Where, with steel, properties can be indicated in a limited number of parameters, like flexibility, breaking strength and surface treatment, the properties of plastic strapping are much more extensive. That's why we will provide a summary of the various options after a short introduction to the production process.
There are various types of plastic strapping. The diagrams contain the production process of the two most important kinds, namely PP and PET. In the case of PP the most important component is a granulate of polypropylene; in the case of PET this is a recycled PET material (for example from PET-bottles or cassettes).
The raw materials are loaded by a hopper, after which it is forced through a worm wheel. This changes the raw material into a syrup-like substance (218 °C). The substance exits a mold as a flat strip, or in multiple strips and is guided through a water bowl for cooling. The material is then reinforced through heating. This stretching ensures that the molecules are oriented in one direction and is thus the deciding factor for the stretch and strength properties of the material. In the case of PET, a second stretching is conducted without heating. Finally, before rolling up, the strip may be shaped and heated and cooled one last time. This is also called "annealing" which serves to homogenize the material and to relieve tensions.
During the production process, the material can exit the extruder as a single surface or as multiple strips. These strips then form the so-called pulled plastic strapping. The production method is a deciding factor for the technical properties of the strap.
- round sides
- low stretch products
- suitable for closing with splicer technology
- accurate with regard to dimensions
- less curving
- right angles
- may pull up on two sides (bi-orientation, greater resistance against splitting)
- suitable for sealing using friction technology
Summarized one could say that cut strapping has very good technical properties, the strap is however not always easy to process.
Plastic strapping can be supplied both smooth and profiled. The manner in which the strap is processed, is the deciding factor when making a selection. If the seal is accomplished using a friction mechanism, smooth is usually opted for. If the sealing is based on a splicing mechanism, the choice is usually profiled. However, there are exceptions to this rule. Modern equipment can often process both profiled and smooth strapping.
Why is the strip profiled?
This has several benefits:
- When the strap has to be processed by a machine, the larger surface offers a more rapid fusion of the material. This is important for the sealing. Not enough profile can therefore lead to a poor seal. With manual processing the profiling leads to a better grip.
- Apart from improved processing properties, the profiling improves the properties of the product, such as flexibility and resistance to cracking.
The most important characteristic is the minimum breaking strength. This is indicated in daN (decaNewton). The elasticity of the material is also important. Plastic strapping will try to return to its original size after stretching. After some time, plastic strapph relaxes (stretching somewhat) and its elastic properties are slightly lost. This is called tension loss.
How the tension loss of the various types of binding straps relates to each other, is clearly reflected in the graph. The graph indicates that the tension of PP strap, after a few days, has reduced to approximately 35% of the original tension. Steel strapping shows very little loss in tension; with regard to properties, PET compares to steel strapping and nylon (composite) is a close second.
The graph does however assume that the upper limit of the elasticity has not been exceeded. Above this limit, the elasticity limit, no recovery of the material is possible.
There is a wide range of plastic strapping. Those worth mentioning are textile, nylon and composite strapping. PP Strap or PET Strap occurs most in the packaging industry The breaking strength, elasticity and tension loss properties of PP are qualitative less than the later developed PET. The price is however more favorable, so that, depending on the application, PP is used in many cases.
Polypropylene (PP) is dull and usually has a checkered profile. PP is manufactured in several standard colors, such as black, blue, white and yellow. Polyester (PET) shines and is often finished in the colors black or green. PP is easy to tear length-wise. With PET this is much more difficult. The specific gravity of PP is lower than that of PET. When it is placed in water, PP will continue to float. PET sinks to the bottom.
Assuming that the cause of quality problems is not only to be found in the strap (it may also be caused by the strapping apparatus or machinery) there are several important main areas of attention.
Most causes related to dust are only noted at a later stage. This dust is released during the strapping because plastic strapping is after all softer than steel, with which it comes into contact during the working process. This means that some material may be left in the strapping apparatus or in the strapping machine. In time this may lead to malfunctioning. This can be prevented by regularly blowing the equipment clean.
Camber is the curving of the material width wise. All material has some camber and it must also comply with specific standards. Machine strapping may have little camber, because the strap is guided through many ducts. Every point of contact has a chance of malfunctioning and with too much camber a point of contact may lead to jamming. The camber tolerance when using a manual apparatus is greater. The degree of curving can roughly be established visually by placing strips along a straight line on the ground.
Rough or uneven ends may cause guiding problems as well as dust and "crows nests". The latter occurs when the crosscut end remains stuck while the machine continues to feed material. The strap is then basically shredded.
This mostly occurs with PP-strap. PET-strap does not split as quickly. It may be caused by too high a pulling force, supply problems and/or splicing problems.
Slipping reels originate when the reel is not wound at the correct tension. The reel will then literally fall apart.
- How do I safely remove the strapping?
Because the strap is wound up tightly, a lot of power can be released when cutting through the material. Eye protection is also advisable. It is recommended that you place your left hand on the strap, stand firm and cut through the plastic strapping. The strap will then roll up in the opposite direction. Make sure that nobody is standing there.
- Does sunlight influence the quality of the plastic strapping?
The ultraviolet rays in sunlight may influence the strength properties negatively. The color of the strap may play a role. Black strapping is very resistant against this effect. White strapping on the other hand, is sensitive to ultraviolet rays.
- What is the difference between PP and PET-strapping?
In general one can state that PET has a higher tensile strength and more restorative power. PET has strength properties approaching that of steel strapping. PP on the other hand is less expensive.
Here too we can state that a heat splice can generate a break strength of 70-90% of the original strength. Friction generates 55-60% of the original strength.
- Does the thickness have an important factor on the strength of the plastic strapping?
Not always, the profile can also be a factor, as well as the composition of the material.
- Can PP-strapping equipment also be used for PET?
No, not always, read the user's manual for further information.
- How do I determine the correct tunnel dimensions with an automatic strapping machine?
You determine the maximum dimensions of the product that you intend to strap. Add approximately 5 cm to gain the necessary clearance and to enable proper splicing.
When you want to strap your product for the first time it is advisable to ask advice from one of our specialists. When you know what kind of strap you would like to order, you may contact us by telephone and indicate your desires. It is however important to clearly define what you need.
When defining reel and strapping you have to take the following aspects into account:
- inner diameter
- strap width
- strap finish
- strap thickness
- strap color
- breaking strength
- strap stretch properties
- how is the strapping implemented, manual or mechanical, semi- or full automatically
With malfunctions the cause often lies in the poor placement of the reel on the machine or the dispenser.
With the placement of the reel on the dispenser you have to consider the following matters:
- The running direction, this is mostly indicated with an arrow on the side of the roll.
- Only remove the material that keeps the reel together if the reel is thoroughly confirmed to the dispenser.
- If there is any cardboard on the side of the reel, you may leave this as is, this will not hinder the unrolling.