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What is the GPA?

The GPA Evo is used to measure the thickness profile of the film offline for quality control. This is achieved by measuring a cross-sectional film sample cut from a film reel.


This device is equipped with two sensors, a capacitive sensor without contact and a micrometer that takes a number of absolute measurements for automatic calibration.

The entire measuring process is automated. The new functions include the automatic stop for segmented films and the automatic elimination of the thick spots left by adhesive tapes used for joining segmented film.


A unique equipment, robust, with high technology and simple to operate. The unit is handled by two operating buttons on the measurement unit and the GPA-Win program on the PC.

Why use the GPA In your company?

Learn about the benefits of using the GPA in your Company.

In its 6th generation of GPA units, the GPA Evo has become the most accurate equipment, easiest to operate and with an even more complete software compared to previous generations. As such, the GPA is not only the most complete but also the best-selling measuring equipment in the world.


The GPA does not need any exterior calibration. Calibration is carried out automatically and accurately during the measurement and with point 0 (zero) as reference point being set with each new measurement. This equipment is used to measure the film thickness, around the circumference of the bubble on blown film and across the web on flat film extruders.

Benefits and Advantages
of using the GPA

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Automatic calibration

Automatic measurement after positioning film sample

Non-contact measurement

Adjusting and calibrating extruders

Suitable for measurement according to ISO and DIN

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Do it like the leading extrusion machine manufacturers, who use our system for calibrating their extruders and maintaining quality.


This software has been specially developed for the GPA film thickness measuring units. With the PC connected to the GPA by Ethernet, all set data required for the measurement is entered by the operator. Once the measurement is finished, the software automatically saves the measurement data and the thickness profile. Even if you are not connected to the GPA, there is the possibility to process and evaluate the recorded profiles.

Learn more about the Software
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Quality in
every detail

See our GPA photo gallery. The complete product in every aspect.

Present in
companies all over the world.

Large companies rely on our solutions.
We are a reference in technology for the plastic industry.

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plasticos generales
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Talk to Octagon

We are a technology center which has guaranteed our customers spare parts and technical support for over 30 years. As holders of an unequalled record of keeping systems running for 30 years, 24 hours a day, we are proud of the stability of our systems and the quality in technical support.

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The GPA consists of the following components:

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Support Rack

Support rack for easy and correct positioning of film samples.

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Software GPA-Win

The GPA WIN software comes with operating system and manual in English including tutorial videos.

Learn more about the Software

All the software we use on our equipment is developed by Octagon.

We guarantee quality on all aspects.

Talk to our team.

Intuition is
our focus

Our software is incredibly easy to use. Here’s some of the data you’ll see on the screen:

Cartesian chart

Polar chart

Gauss distribution

Tolerances (%, μm, 1-, 2-, 3-Sigma)

Cpk machine capacity

Fourier Analysis

Profile analysis

Learn more about the Software
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Join us

Be part of one of the most innovative companies in the world.

Total Quality

Give it a go on the road to Quality Management.

Technology Centre

Industry 4.0. Together with our customers we are creating a digital future.


Be our business partner and we will focus on the individual needs of your process.

Download the
GPA guide

Click the button below to download the GPA guide and it will be sent it to your E-Mail address.

Coming soon.Stay tuned!

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Frequent questions

This is very fast and simple: just put a ruler or guide on the bench and cut the samples in a strip approximately 10 cm wide. Then insert the film samples into the supplied support rack with guide rollers. The width of the film sample does not have to be accurate, e. g. it can be anything between 7 cm and 10 cm, as the equipment reads in an area of only 4.5 cm. So, no time needs to be lost when preparing the samples. It’s quick and easy.

No. The equipment has two sensors, one capacitive, the other absolute. Before inserting the film sample, the absolute sensor is used to determine the zero point as a reference. After this procedure, the measurement is carried out, the capacitive sensor measuring the film sample and the absolute sensor taking reference points for automatic calibration. For laboratories that require certification for ISO standard we provide a certificate.

Yes, the GPA is flexible. In addition to the DIN and ISO standards, measurement points can be every mm or adjusted to a number of your choice. Example: If only 10 points are required, 10 points are measured.

Yes, this system is widely used to calibrate extruders. Just fix a reference point on the die and mark the bubble exactly above this point. Then measure the sample of the tubular film.
The measured thickness profile will be presented in the polar chart of the GPA-Win software where the number of the die bolts can be selected This information allows the operator to adjust the die by either tightening or unfastening the respective die bolts.

No, in addition to tubular films it also measures segmented film samples individually or joined by adhesive tape.

Yes, laminated, pigmented and film with additives, etc. As the system operates with two types of sensors it is possible to select the measurement mode. Simply disable the capacitive sensor and use only the absolute sensor making point-to-point measurements.

Yes, the software includes a Fourier
Analysis of the measured profile. The results are shown in a graph where sine waves and their importance are analysed to indicate the distribution of symmetrical thick and thin spots. Some of these correspond with symmetrical faults of the extruded film which can be corrected. The importance of the symmetrical fault is indicated by the height of the corresponding vertical bar. For example, a film sample with 8 symmetrical thick and thin spots may indicate a problem of melt distribution caused by wrong temperatures. 6 symmetrical high and low spots may indicate a bad distribution of the cooling air. Often 13 and 15 symmetrical spots occur with an additive not plastifying well. Then just change the additive and make a new measurement to see if the problem disappears.

Yes, as a PDF. You can program this report to include your own logo.

Yes, the data can be saved in CSV format (Excel) and made available in the format required.

Simply select the norm required and the system will distribute the measurement points in proportion to the sample length.

To make it convenient we offer video training, if you have any questions, online training via Skype may be organized.

In two ways: The first is using the equipment to check the quality of extruded film, including from machines with online thickness control. This because the GPA is much more accurate measurement device than any online measurement system.

The second is quality control of the production process. Here the data is collected from all film reels of a production order, in this way a history is generated and a pre-established quality standard is created in which the GPA Evo is used to monitor the quality of the film produced.

The measuring unit is capable of measuring lengths from 32 cm to 20 m. The length of sample may be from 52 cm to 6 m on the standard support rack. For greater lengths oversize support racks are available.

Yes, it is possible to measure segmented samples, either separately one by one or the segments joined to a tubular strip with adhesive tape.

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Who we are.
What we do.

Welcome! We are Octagon, a world reference in technology for the plastic industry.

Meet Octagon! Ask for a quote

Automatic Air Ring

Sensor de Espessura PMS-B - Octagon Blown Film Control

Thickness Sensor



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Width Measurement

dosador gds eco

Gravimetric Dosing

produtos especiais

Special Products

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Automatic Width Control

upgrade maquinas

Upgrade of Blown Film Extruders and Co-Extruders

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Take advantage of all the benefits of the GPA. Acquire it for your Company.

Octagon measuring equipment: We have been leaders in thickness profile control and measurement for over 30 years.

Octagon Blown Film Control GmbH:

Nuernberger Straße 119 D-97076 Wuerzburg, Germany.
Telephone +49 931 27 96 70 Fax +49 931 27 96 799