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Meet our gravimetric dosing and feeding solutions for blown film

Get to know our reliable gravimetric feeding, weighting, and dosing solutions for plastic film extrusion.


What are the benefits of gravimetric systems

Gravimetric systems offer several benefits in the blown film extrusion process. Here are some of the advantages of using gravimetrics:

Flawlessly align with customers' specifications

High level of accuracy in material measurement, eliminating potential errors

Precise material feeding and constant ratio between component materials

Real-time monitoring and control allowing automatic adjustments

Feed component materials simultaneously avoiding separation or de-mixing

Get to know

How does the GDS work?

The GDS system achieves exceptional performance in gravimetric dosing and extruder control by combining WLS (the reliable Octagon throughput measurement unit) with screw feeder units. It employs a loss-of-weight measurement method to accurately and reliably measure both the main material and additives.

By installing the GDS unit directly on the material inlet of the extruder, it eliminates the need for separate handling or mixing of different materials. There is no requirement for an additional mixer. Moreover, the GDS system incorporates an advanced dosing concept that enables the easy replacement of dosing screws without the risk of overdosing.

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Quality control, optimised products, production increase, savings in raw materials

In addition to precise gravimetric dosing of additives required for film composition, the GDS module also precisely measures the consumption of each material by means of the patented Throughput Measuring Module WLS.

This exclusive system features high quality airtight load cells, ensuring reliability and accuracy in throughput measurement of each component. In addition, a unique external hopper protects the inner weighing hopper from external influences and vibrations.

With this information on material consumption, the ScenEx software is able to calculate and automatically control the target screw speed of mono-extruders. In case of co-extruders, the screw speed is controlled individually for each layer.

In this manner, it is possible to control the production of the extruder as well as the average thickness of each layer of film. Simultaneously, the weight per metre of film is automatically controlled by synchronisation of the haul-off speed, thereby ensuring a constant average film thickness.


Frequent Questions

Basically there are two reasons, firstly for most accurate dosing of the plastic additives, secondly for accurate recording of the grams used per meter of film produced.

The return on investment is based on the percentage of savings of plastic additives and the accuracy of the grams per meter of the film produced.

The superior accuracy of the system allows you to work with a lower percentage of additives per screw. Example: If with your current conventional system you are using 4% of a plastic additive, with the GDS system you can reduce this percentage due to the fact that the dosing control is more accurate and the blend by dosing screws more uniform. This leads to a reduction in consumption of additives and pigments per kg of film produced.

The accuracy of the grams per meter control ensures that each kg of film produced is identical. This helps in the control of the thickness profile and the process in the final finishes. For packaging sold per unit the accuracy ensures that each kg has the same the volume of packaging.

Faults in the gravimetric control leads to several problems and most companies do not know whether the equipment is accurate or not. Without an equipment such as the regular collection of measured film samples from film reels offered by the GPA it is very difficult to identify the variations. This will result in a number of problems in the final packaging process. For this reason, accurate and reliable equipment such as the GDS Gravimetric Dosing Unit ensures stability and confidence in the extrusion process.

The equipment pays for itself in a few months. This is based on the savings made in plastic resin due to the accuracy of grams per meter produced and the reduction of the percentage of pigments and additives used in the process.

The Gravimetric Dosing System GDS is incomparably more accurate and ensures a much more homogeneous blend of materials. This is achieved by each component having its own individual load cell and a dosing screw system fully integrated in the extruder assembly. The dosed material enters directly into the extruder assembly without going through any intermediary mixing process eliminating separation of components due to different densities and granulometry of the materials. The concept produced by Octagon gives stability and continuity and its electronic components and load cells are of the highest quality ensuring stability to the system.

The batch blender system has been developed to be inexpensive, with the concept of one single load cell for all components, i. e. additives, pigments and main materials releasing the complete volume or batch into a mixer. Variations in density and granulometry prevent this type of system from being accurate due to the physical factors of gravity itself. Additives and pigments do not have the same grain size as the resin material, the density also differs greatly between the components. So it is impossible for a mixer to maintain uniformity in the blend once the material leaves the blender and is exposed to machine vibration. We should also consider the variation caused by the accumulation of materials in the corners of the blenders. Most Batch Blenders require constant attention by the operator for load cell calibration.

In conclusion it is obvious that the GDS Gravimetric Dosing Unit is technologically superior, more accurate, more stable and more reliable.

In the extruder the gravimetric unit GDS is responsible for controlling the grams per meter in the film produced. On the other hand the SmartLip Air Ring controls the thickness profile by correcting thick and thin spots on the bubble. The algorithms included in the Octagon software integrate and synchronize the two systems ensuring an excellent result in the quality of the film produced.

Yes, our system is modular and can be enlarged up to seven components step by step.

Yes. The dosing screws are quick change and allow any change between components.

No, on the contrary. Our software is transparent and very easy to operate.

First, the respective dosing unit has be completely emptied of all materials. This is an easy job by simply opening a latch under each dosing screw. Our system is designed in such a manner that no grain of raw material gets stuck contaminating the following product.

Ready to take the leap?

Talk to our sales team today.

Octagon enhances blown film extrusion all over the globe.

Meet our solutions​

Brought to you by Octagon's extensive 35-year history in manufacturing solutions for the blown film industry

Discover Octagon’s extensive range of solutions and products specifically designed for blown film extrusion. Contact our sales team today to unlock new levels of productivity and maximize your efficiency.

Automatic Air Ring


Film Thickness Measurement

PMS-B | PMS-FF | Venpad

Offline Film Gauging


Film Width Control


Gravimetric Dosing & Feeding


Film Production Management

Octagon Software

Film Extruder Upgrade

Equipment Upgrade

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