Suprotik Das, MD, Nordson India, in this article, focus on one aspect of packaging — the application of hot melt adhesives (HMAs) for different bonding applications
With the Indian consumer products industry becoming more and more competitive, today’s businesses are faced with two critical imperatives:
- Constantly improve product features, in order to remain attractive to consumers.
- Manufacture these products at the lowest possible cost.
Why? Because only if your products are more attractive from those of your competitors, will there be a reason for your customers to prefer your products over those of competition. With that, will come greater market share and greater success. And minimising the cost of manufacturing something is always an advantage.
So, why is this important for packaging professionals? Two reasons:
- Badly packaged products result in costly rejects. And while rejects detected in the factory are bad enough, those detected at the point of sale are a disaster! Exhibit 1 is a photograph taken recently in a supermarket in Bengaluru. It shows numerous cartons where the adhesive has popped open. Needless to say, such defective products never get sold.
- Perhaps more critically, packaging has evolved into something greater than a means of protecting a product. Today, packaging is a critical part of the marketing communication process. Marketers often spend enormous amounts of money on slick advertising to create a brand. But, just as an expensive TV commercial says something to your customers, a badly sealed, open carton on a supermarket shelf silently but eloquently says something about your company, your product and your credibility. Interestingly, many businesses completely ignore the damage that is done to the brand by a poorly packaged product, even though such a product has the potential to do grave and long-lasting damage to their brands.
A typical application might, for instance, be the tamper-evident sealing of carton flaps using HMAs.
For creating consistently sealed cartons, it is not just important to apply the HMA at the right quantity and the right place. It is critically important to know whether that has happened. This knowledge allows for incorrect applications to be immediately corrected, so as to limit the damage.
It is for this reason that the ability to track the application of HMAs in real time, has become so important. Nordson Corporation, a leading manufacturer of adhesive dispensing systems, has recently launched a product that provides this capability.
The Nordson ProBlue Liberty ATS (Exhibit 2) provides a way to track and measure adhesive usage in real time. (ATS stands for Adhesive Tracking System.) The system combines all the benefits of an automatic fill, tankless melter, with the cost-saving capability to minimise adhesive consumption while improving package quality.
Here’s how it works: Solid pellets of HMA are fed on demand into the heated grid of this tankless melter, from a bulk storage container. The HMA gets rapidly melted in the grid and is ready for application in a very short time. This molten HMA flows through the manifold into an integrated flow meter (Exhibit 3) for direct flow measurement. The HMA flows around the gears of the meter, causing them to rotate. Inductive pickups sense this rotation and send pulses back to the controller. The HMA now continues its path through the hose to the applicator. As the applicator dispenses the adhesive, the integrated flow meter allows for real time tracking of the volume dispensed, and alerts the system when the amount of HMA is out of a pre-determined range.
The user has the ability to set upper and lower limits of the average quantity of adhesive per product. If the adhesive volume goes outside the set limits, the system can be configured to send a signal based on custom specifications. For instance, an increased system pressure could result in too much adhesive being dispensed. In such a situation, the system would register that the volume is outside the set limits. The line would stop and the light tower would be illuminated. Likewise, a clogged nozzle or failed solenoid would cause the system to notice a drop in adhesive volume. It would stop the line, preventing wasted product and potential pop-opens.
By tracking the precise amount of adhesive dispensed onto a package, users can ensure that the required amount of adhesive has been applied – not too much, not too little. Too much adhesives causes adhesive waste and increases cost. In fact, too much adhesive could actually result in a defective product, with the excess adhesive getting smeared on decorative parts of the package. Too little adhesive can cause an inadequate seal and a product that will get rejected.
The ATS also provides a product detector located on the production line that senses products from leading edge to leading edge. This information is sent back to the control box. Adhesive is measured over the product detector’s pitch. The controller then uses this information to calculate the average weight per product (Exhibit 4).
These adhesive tracking capabilities can also be added to existing ProBlue or ProBlue Liberty melters using an upgrade kit. The flow meter can be directly attached to a manifold hose port, or it could be remotely mounted with a heated hose.
To summarise, the ATS feature does three things. It enables the customer to:
- Optimise and track add-on (adhesive) per product, thus eliminating waste, while ensuring that the required amount of adhesive has been applied.
- Prevent out-of-control processes with operating alarms and line stops.
- Analyse historical data to improve processes.
The use of this technology enables the user to enjoy the benefits of real time flow tracking. It ensures that the adhesive process delivers products of consistent quality at the lowest product cost. In short, the possibility of excessive adhesive consumption is virtually eliminated, as is the possibility of poorly sealed packages leaving the factory.