Validating sealant film quality

Extensive sampling and testing protocols are designed to validate the sealing process for flexible packaging. Scott Fuller of CMD explores its importance in bag/pouch production

As the flexible packaging market began to grow and stretch its boundaries into food, beverage and medical applications, end users began to demand higher levels of quality and in some instances full validation of the sealing process. This, in turn, required converters to demand more robust sealant films from their suppliers. However, this did not satisfactorily mitigate the risk so extensive sampling and testing protocols were developed, adding time and cost to the production of these packages.

Plastic packaging substrates possess subtle internal variations which can affect the quality of the seal produced on it. The processing machinery itself possesses more variables. This all adds up to the potential to yield sub-standard seals which could make their way into the supply chain undetected.

Enhanced process management and realtime process feedback in the production of bags and pouches is absolutely vital.

Art or science?

Successful converters will minimise the ‘art’ of producing bags and pouches and maximise the ‘science’ of it. Converters faced with price-reduction pressures from customers, volatile raw material prices from suppliers and wageand- benefit pressures from their employees, had to figure out how they could stay in business and remain profitable. To do so, the leaders in the industry turned to data.

Process engineering positions were created solely to drive internal costs out of the manufacturing process. Data-driven process analysis tools have been utilised to provide significant gains in overall equipment efficiency (OEE). As a result, millions of dollars have been saved, simply by recognising and correcting process waste contributors. While gains in productivity are essential, providing a higher quality product at a lower cost can gain the converter considerable market share.

It’s all about the seal

When attempting to create a seal between two separate substrates there are three critical components one must control: time (or dwell), temperature and pressure. The extent to which one can measure and control all these attributes is directly proportional to the overall quality of the seal itself. Up to now technology has been focused on ‘tightening-up’ the process, not necessarily controlling it – mainly because there was no real need to do so. As the market for high-end pouches and bags continues to expand into more demanding applications, quality requirements become increasingly stringent and product traceability imperative. These requirements are aimed at providing the end-user with true confidence in the integrity of the pouch/bag. Currently, most quality and process data is manually collected, entered and analysed. But all of this takes time and people, both of which add cost to the overall process, not to mention the potential for human error. Furthermore, current technology provides accurate data primarily for temperature. In some instances, you may be able to collect accurate pressure data. However, dwell time settings are typically only references based on mechanical position and not actual time in contact with the substrate. This lack of solid, reliable data produces uncertainty which in turn produces more frequent testing and therefore cost.

The solution

Process management can be a reality for today’s pouch converters. It needn’t have a negative impact on productivity nor should it require extra people to manually collect data and manage paperwork. Such a possibility simply requires the right tools. Making tools available to converters that will allow them to automatically capture actual real-time measurements for temperature, pressure and time, will significantly change the flexible packaging and converting landscape. That change is now approaching. Soon converters will be able to automatically monitor and control the entire sealing process using enhanced process management tools available exclusively with PDI Intelligent Sealing Technology. This traceable data for each aspect of the process will allow converters to verify the quality of their product to a level never before attainable, thus creating the highest level of confidence in their product quality. Such verifiable product quality may command a premium price, garner more market share or even provide a means to enter new markets. The first challenge for PDI was to develop this level of capability at a cost that will still allow the converter to realise the benefits to the bottom line. Once this was achieved the technology team at CMD/PDI discovered new possibilities.

A bright future

Think about your pouch-making process. You either manually currently collect process data around temperature, pressure and time (or dwell) or you have installed secondary systems to help to automate this operation. Either way, most of the data you collect is more of a passive measurement on which you must act rather than an active means of controlling your process. If, for example, an operator fails to take a set of measurements or take the necessary action to correct a variation trend, your product has the potential to be compromised – a product of ‘the human factor’. This is not to minimise the importance of data collection. But can there be something more? Consider Intelligent Sealing Technology from PDI/CMD which successfully bridges the gap between passive data collection and active process management.

Intelligent sealing technology

The engineers within the PDI product group have been hard at work learning about their customer’s processes and understanding the pain points converters experience as a result of processes that rely too much on the human element. The result of this effort was the introduction in 2008 of a servo- actuated sealing platen used primarily in the medical packaging market. This was able to successfully harness the data already available within the sealing system to provide passive measurement data as well as a means for the machine to self-monitor and self-correct for process deviations.

Based on the success of this technology it became apparent that the same level would be well-received in other areas of the medical packaging market as well as within the stand-up pouch market in general. Imagine your customers’ response when you tell them that you can provide them with seal data for each pouch they’ve purchased from you. Imagine their surprise when you tell them that you can also provide them with an assurance of real-time automated process management not previously available.

Temperature, pressure and time data are automatically collected for each strike of the sealer. This can be monitored in graphical form in real-time on the machine’s HMI. In addition, this data is stored for up to seven days within the machine’s PLC so that the process engineer can upload the data to an

Excel Spreadsheet for full statistical analysis. This data is fed back into the system for each strike of the sealer so that if a deviation trend is sensed the machine can self correct to maintain a stable process.

Sealing rubber degradation is now recognised and corrected for. Differences between an ‘old’ sealing surface and a newly replaced surface are automatically sensed and corrected for. Seal-bar contact time is now more than a ‘move-parameter’. The system now senses the moment the bar makes contact, so mechanical binding or sluggish cylinders no longer need to be factored in; dwell time is precise, consistent and repeatable. Temperature deviations are effectively recognised and isolated and the machine will know to stop itself when a problem is encountered: this is Intelligent Sealing Technology.

CMD Corporation

T: +01 920 730 6888