Wall thickness measurement

Uniform material distribution as well as uniform wall thickness are of crucial importance in the production of jars, bottles and tubes for cosmetics. The wall thickness of plastic bottles, for example, has a direct influence on container rigidity, deformation, stress cracks, base stability and internal pressure resistance. The closure strength, transparency and surface quality are also ultimately dependent on the wall thickness.
With glass containers, on the other hand, testing the wall thickness is an important criterion for saving material and thus reducing weight. At the same time, however, minimum target values must be adhered to in order to prevent breakage and chipping. The human eye is far from capable of doing this. The wall thickness of bottles, jars or even aluminum tubes cannot be assessed in this way. Hence, thickness values obtained through exact measurement are required.

The MiniTest FH from Elektrophysik provides such measured values for wall thickness. The portable measuring device is ideal for measurements of up to 24 mm wall thickness. Its ergonomic housing shape and easy handling make it the perfect measuring tool in production. It can be seamlessly integrated into automated processes. It is thus the ideal solution for efficient quality control in the production of plastic and glass containers for cosmetics.

In recent years, material savings have become a more important factor than ever in the development and production of plastic containers. For example, the weight and associated material thickness of plastic containers has been constantly reduced with the goal to save costs for raw materials and improve the environmental balance. At the same time, product safety, high transparency and brilliant surfaces are imposed through specification sheets.
In consequence, continuously checking the wall thickness on the production line is essential. This is because repeated irregularities in the wall thickness must be detected at an early stage before they become visually recognisable as a reduction in quality.
In addition, the wall thickness measurement of preforms and the subsequent measurement of the bottle after the blowing process provide important conclusions for optimising the preforms. Continuous inspection of preforms helps the user to sort out defective items at an early stage so that they are not even transferred to the production process

The device delivers these reliable measurement results directly on the production line – regardless of colour, unlike some optical systems. The compact measuring device, consisting of a control and display unit and a sensor connected via cable, provides information on all variations in wall thicknesses within a very short time. The device can be combined with a wide range of connectable sensors and thus efficiently solve numerous measuring tasks.
The non-destructive measuring device is intuitive to use and achieves precise measurement results on all non-magnetic materials, regardless of size and shape. Even measurements on sharp edges, narrow diameters and complex geometries can be carried out easily with the MiniTest FH device. The measurement results are visualised on a 4.3” colour screen with a resolution of 800 x 480 pixels. The control unit also has an integrated rubber rim for protection and a better grip, as well as foldable stands.
The device has a continuous measuring mode that allows the material to be scanned with the probe. The current readings as well as the minimum and maximum values and the average value are displayed. With a preset logging rate, individual values can be transferred to the statistical evaluation during the online measurement or transferred directly to the evaluation software.
 It can be used to comply with international standards such as the ISO standards as well as industry guidelines that define precise minimum requirements for wall thicknesses.

As part of quality control, the device can lead to savings of several tons of material per year in the production of plastic containers, for example, by adjusting the wall thickness to the target specification. It can also be used to optimise compliance with minimum wall thicknesses to avoid rejects and possible complaints. 

• Measurement of non-ferrous materials up to 24 mm wall thickness
• Applications: Containers and bottles made of glass, different types of plastic, aluminum, tin plate, stainless steel
• Extreme accuracy thanks to digital signal processing
• Direct data import into evaluation software
• AI-based quick calibration function
• Splash-proof housing: industrial standard IP65

To cover a wide range of measuring tasks, a selection of sensors is available in angled and straight versions for hard-to-reach places with various measuring ranges, reference spheres and wires as well as different designs that have been modified for the specific measuring tasks. Even with sophisticated perfume bottles with complex designs and different embossing, MiniTest FH supplies exact measurements. The measuring range of 0-24 mm is extremely flexible. 

All connectable sensors work with the SIDSP method (sensor-integrated digital signal processing). The transmission of the already digitally-processed measured values from the sensor to the evaluation unit ensures maximum accuracy.
And thanks to the innovative AI-based quick calibration, a zero calibration can be performed for every sensor and ball diameter in less than ten seconds at the touch of a button, increasing the accuracy of the measured values by 50 percent.
The device offers various interfaces for data transfer to a PC or directly to a CAQ system: Individual measured values as well as the entire statistics can be transferred via USB, RS-232C or Bluetooth. As a special feature, it enables the direct transfer of measured values to an Excel spreadsheet or other evaluation software via USB keyboard emulation.
In the statistics area, a trend diagram can be created to graphically illustrate the measured values, making it possible to quickly identify deviations. A histogram provides information on the distribution of the measured values for viewing larger production quantities. Real-time feedback loops can also be implemented to send measurement results directly to the production control system so that parameters can be adjusted immediately. Last but not least, all measurements can be stored in folders and measurement series that can be freely named.