Some products – such as nuts, chips, and other free-flowing foods – move very easily through a production process.
But dealing with sticky products is an entirely different scenario.
Sticky products may want to stick to various contact surfaces within machinery – or to each other – which creates all sorts of potential obstacles to ensuring that weighing, filling, and packaging processes move smoothly. It’s where applications engineering becomes a critical part of the process when choosing packaging machinery.
While there are many different ways to handle sticky products, here are 5 tips we usually build into our processes.
Whenever dealing with an overly sticky product, it is generally recommended to use dimpled, rather than flat surfaces, on the multi-head weigher, bucket elevator, incline conveyor, and other contact surfaces.
The dimpled texture creates less surface area for the products to stick to throughout the packaging process. Depending on how well the product flows, it may also be advisable to make additional modifications – such as tilted feed pans or a spinning cone accessory – to the multi-head scale used.
In general, multi-head weighers are fast and more accurate than linear scales. But when dealing with stickier product – from gummy vitamins to cannabis edibles – the concept of clumping creates a potential for overweights in a linear scale.
In a linear weigher, product is metered out at a higher rate of speed for most of the target weight, and then dribbled in for the remaining portion. That faster “bulk” fill accounts for anywhere between 70-90 percent of the target weight, depending on the fill amount and the flow characteristics of the product.
The potential for an overweight is greater when clumps are present in the dribble portion of the scale. If a product intended to be 5 oz. sits at 4.9 oz, and a large clump of product is the next piece to drop, the package will likely be over.
With a multi-head scale, the amount of each product contained in the weigh buckets is combined in order to reach the final weight – regardless of whether the product in each bucket is made up of single pieces or one large clump.
With many products, such as cheese shreds or crumbles, even a dimpled surface isn’t enough to keep product moving, which is when flow agents can be introduced into the process. These agents – generally cellulose-based – allow products to move through scales and other equipment without sticking.
The moisture content inherent in sticky products makes climate control in the packaging facility/room a critical factor in ensuring the product moves smoothly through the process.
The stickiness of gummy products is often reduced when they are refrigerated, which may allow the product to be weighed and packaging more quickly.
When dealing with pastes and other similar products – such as peanut butter – the opposite is true. Heating up the product allows it to flow and be pumped more smoothly.
Humidity is also a factor with many products. When dealing with products such as granola, the moisture content of the air can react with honey or other sticky ingredients, creating the potential for clumping.
It’s always important to ensure that the forming tube/container opening is large enough to accommodate any individual piece of the product.
But if multiple pieces clump together, it creates an added potential hurdle in the filling process.
One way to overcome that, as Ohlson does in our gummy packaging systems, is to use vibration to break up the clumps and meter out the filling process to ensure a large clump doesn’t get stuck in a container opening.
The obvious counter-effect of metering out the filling process is that speed can go down. But by filling multiple containers at one time, the overall output speed of the system can still be maintained.