In high-speed packaging lines, heat-sealed packages are often subjected to forces before they have time to cool. Their ability to withstand these forces with the seal intact is known as hot tack seal strength. A new generation of RDM testing machines uses B&R hardware and software to make the hot tack testing process as quick and straightforward as picking a music playlist.
Over the past 35 years, RDM Test Equipment has established itself as a leader in hot-tack testing technology used by film producers and converters who supply product manufacturers and packers.
Without a perfect seal, packaged food and pharmaceuticals are at best unfit for sale and at worst a health risk for the consumer. Seal integrity is therefore a vital factor in minimizing waste and preventing costly returns and recalls. For heat-sealed packaging, the first few seconds are crucial. High-speed lines subject the packages to forces before the material has a chance to fully cool down. The ability of the seal to withstand these forces is known as hot tack.
Along with other key properties like friction, thickness and tensile strength, hot tack is tested in laboratories, using machines like RDM Test Equipment's HT-2PC. For its latest generation of hot tack testing machines, RDM has used B&R automation technology to make the process faster, easier and more reliable.
Hot tack seal strength testing used to be a slow process that required each film sample to be loaded manually into the machine. Although each test itself lasted only a few seconds, it would take a skilled operator several minutes to cut a sample, load it into the machine and then remove it to load the next sample.
With the new machine, the loading and feeding process is now automatically controlled and indexed by a B&R PLC. In addition to reducing the likelihood of loading errors, this enables multiple tests to be carried out on the same length of film in rapid succession. Operating the touch screen user interface is similar to queuing up a music playlist on a smartphone or tablet. The user can stack up multiple tests, which the machine then carries out sequentially. The touch screen alerts the operator if the test sample breaks, or if there are any loading or feeding errors. Testing sequences can be programmed and saved into the system according to individual customer requirements.
The machine can handle many different film types, from traditional hydrocarbon plastics to new environmentally friendly alternatives. And it can carry out up to 40 tests on the same piece of material – in a fraction of the time it would take to cut and load the same number of samples manually.
Automated loading and sequence indexing reduce the amount of human interaction in the testing process. This eliminates the risk of operator errors, such as inadvertently loading a sample the wrong way around. It also prevents tampering with the results, ensuring that clean data is measured and reported automatically.
A 15" swing arm Panel PC with an Intel Atom CPU uses a Windows-style interface for transparent, user-friendly operation, while B&R's Automation Studio software solution easily manages the complex algorithms required by the testing process. Hypervisor software allows Windows or Linux to run alongside B&R's own real-time operating system, making it possible to combine a controller and HMI PC in one device. The system uses industry standard OPC UA communication to allow connectivity between the machine and any external devices or data recording and analysis systems.
The software also introduces more efficient interaction capabilities with the test results. For instance, after multiple hot tack tests have been performed, the software provides a trend analysis graph. This gives the operator a detailed picture of the heat-sealing characteristics of the film between two temperature extremes. Having precise control of process variables such as temperature, pressure and duration enables an optimal balance between material specifications, packaging machine speed and seal integrity.
B&R's automation solution makes hot tack testing very simple, yet also extremely flexible. Results can be viewed locally as CSV or PDF files or printed test reports, and raw data can be exported automatically to third-party software applications via OPC UA. Increased automation of processing and reporting means that more data can be processed in less time and with greater repeatability. It opens up the potential for sophisticated trend analysis, giving operators improved insight into performance data.
B&R's scalable hardware and software allows each customer to use the touch screen size that fits their requirements. B&R's mapp View solution makes the HMI screens exceptionally scalable. Changing display size or switching from portrait to landscape format is easy to do without having to rewrite any software. "Rather than write lines and lines of code to build a user management system, alarm system or motion control sequence from the ground up, we were able to simply configure the ready-made mapps," says RDM Sales Director Phil Neal. "And since they make complex algorithms so easy to manage, our programmers can focus entirely on the machine process."
A key requirement for the new machine design was that it be future proof, ensuring proactively that the equipment would be ready to meet evolving customer needs. "New alternatives to hydro-carbon plastic films are being developed all the time," notes Neal. "But before customers can use them, they need to know exactly how they will perform and whether they can withstand the rigors of high-speed production."
With B&R's improvements to stability, security and repeatability, the new RDM machine allows customers to carry out more testing in less time, delivering both improved quality and reduced time to market.
Sales Director, RDM Test Equipment
"Rather than building a user management system, alarm system or motion control sequence from the ground up, we were able to simply configure the ready-made mapps. They make complex algorithms easy to manage so our programmers can focus entirely on the machine process."