With test devices from CETA Testsysteme GmbH, integrated into a test stand from sab Burkhardt GmbH, a flexible solution for leak testing canisters (Jerrycans) and plastic drums has been developed for a well-known manufacturer in the packaging industry and is now being used successfully in the production line.
Canisters and plastic drums are manufactured using a blow moulding process. The subsequent weighing and leak test of the still-warm products are used for quality control before delivery.
Many of the leak test benches currently in use have been customised. Higher-level control systems control and monitor the mechanical adaptation, the pneumatic valves for filling the products and analyse the pressure changes detected by pressure sensors. In many cases, a distinction is only made between good and bad parts.
This was also the starting point for this project. The test station, which had been in use for many years, was to be replaced by a new system with significantly enhanced functionality.
The special challenges
What was required was a flexible solution for different product variants, an increase in the precision of measurements, the use of testing technology with a traceable calibration certificate and the documentation of measured values. It also had to be possible, Both warm and already cooled products to be examined. Previously, these were channelled out as rejects.
Test bench and testing technology
The universal solution covers the testing of different products with different heights and volumes (between ten and 220 litres). The test process is standardised through the use of a CETATEST 715 LV leak tester, which is specially designed for the Leak testing of large-volume packaging is suitable. After the start impulse from the system controller, the test device controls the entire test sequence. The test pressure inside the test part is checked dynamically during filling. Once the target value is reached, the stabilisation and measurement phases follow. The leakage-related pressure loss is measured and the measured values are transmitted to the higher-level control system.
(Photo: sab Burkhardt GmbH)
The programmes for the different product variants can be entered and managed via an HMI (recipe management). This data is transferred to the leak tester via the bidirectional Profinet interface. This means that a replacement device can be integrated within a very short time. The measured values are recorded, which supports the documentation of product quality.
Testing and performance data
The product is filled with compressed air via an opening in the adaptation. Back pressure effects make it difficult to precisely monitor the test pressure in the filling line. For this reason, the test pressure is monitored via a second opening. In addition, a calibration standard can be connected to the measuring circuit via a pneumatically controlled valve, allowing the test stand to be checked at regular intervals.
Due to the blow moulding process, products that are 60 to 80° C warm and also cold (e.g. after a production stoppage) can falsify the measurement result due to different temperature-related pressure changes. For this reason, the temperature of the product is measured with a sensor. Depending on the temperature, a suitably parameterised test program is selected and dynamically transmitted to the test device via Profinet.
At test pressures in the range of 100 mbar, holes up to a minimum diameter of 0.4 millimetres can be reliably detected. The total test time, including turbo filling for large-volume products, is between five and 30 seconds for cold and warm products, depending on the test volume.
„Leak testing large-volume products in the production process in acceptable overall test times and detecting the smallest holes is a metrological challenge.“ Dr Joachim Lapsien, Sales Manager of CETA Testsysteme GmbH, Hilden
The profile of the realisers
The CETA Testsysteme GmbH is a manufacturer of physical testing devices („Made in Germany“) and has more than 30 years of experience in the field of industrial leak testing and flow measurement in the production line. Customers from a wide range of industrial sectors use the test devices to safeguard production. In the packaging industry, in addition to large-volume packaging (IBCs, canisters, drums), components such as stopcocks, connections, joints, safety valves, pressure equalisation elements, pipes and closures can also be tested for leaks and flow. the company is certified to DIN ISO 9001, and since 2004 the calibration laboratory for the measurand pressure has been accredited to DIN EN ISO/IEC 17025 (D-K-19566). several thousand CETA test devices are in use around the world, which are supported by international representatives close to their locations.
sab Burkhardt GmbH has been operating successfully in the field of control and automation technology since 1991. The range of services includes the project planning and realisation of complete systems from simple devices to complex production systems. Another focus is the automation and modernisation of existing control systems or their redesign (retrofit).
