Whether making, moving or cleaning with an eye for health and safety, there are plenty of useful ingredients for mixing and blending.
While much of the process industries’ various sectors provide visible proof of the transfor- mational influence of new era technology and systems, certain areas have been less able perhaps in demonstrating their effectiveness in transitioning.
Mixing and blending is, to some extent, a prisoner of the perception that it remains in the pre-4.0 age with fewer obvious signs of progress. The reality of course is more nuanced.
The Vita Group is one of Europe’s leading manufacturers of flexible polyurethane foam, used extensively as a cheap and effective ingredient in bedding and furnishing.
In order to make foam, explains regional director Mark Lewis, two chemicals are mixed and the subsequent reaction creates gas. The gas then creates bubbles in the liquid which then expand, making a flexible PU foam.
Manual handling at floor level has increased productivity, eliminated dust, and improved worker safety
Avni Patel, owner, SMK Nutra Makers
However, the process has challenges when it comes to maintaining product consistency because the reactions of the two chemicals are impacted by humidity and temperature. On a warmer or wetter day, says Lewis, when the moisture is above or below average, it will react faster.
“Air pressure additionally has an impact – if there is high air pressure, the foam will swell. The air pressure during winter and summer means the foaming process is like making a sponge cake but not knowing the temperature in the oven,” he continues. “A change in weather conditions can therefore have a significant impact on the quality that’s produced.”
Not only does this create a commercial concern; there is also a potential health and safety issue because the foaming reaction is exothermic, generating its own heat, so if the process goes wrong the foam could self-combust and ignite.
Thus, one must change the chemical formulation depending on the weather. Therefore, traditionally, these formulations had to be determined on a daily basis by individuals with sufficient expertise in the practice.
Far from shying away from seeking new methods to improve the reliability of combining ingredients – and doubtless mindful that the incidence of unpredictable and extreme weather conditions has been on the increase – The Vita Group harnessed data analysis.
It developed a project to examine the relationship between formulations and atmospheric conditions, with the aim of creating an algorithm that would confirm what chemical formulation was required to achieve the right properties of foam in a specific environment.
A pilot was carried out at the group’s Hungarian site, chosen on account of the central European country’s often extreme summer weather; it was then extended to neighbouring Poland and also Lithuania before being introduced to the company’s Manchester Middleton base in the UK.
To begin with, the chances of exothermic reaction and ignition can be significantly reduced using the algorithm, points out Lewis.
He adds: “The other notable aspect of this project is that the outputs produced can be put into business analytics tools, allowing The Vita Group to visualise workflows through high quality data. That data provides early warnings of possible issues.
“An example is the quality of temperature control over chemical flows – for example, if some of the additives in solutions are too diluted. “A solution could be 5kg of chemicals and 5kg of another substance, and traditionally those mixtures are created by hand where human error can creep in. By changing to an automated pump system there would be better consistency across products.”
On a higher level
Now data is used in a more granular way to enable higher and safer standards of work, with a reduction in batch-to-batch variants in density across foam produced.
Consistency in mixing ratios is equally important in the food and drink sector, where it can also be compromised during transportation within a factory.
Conveyor systems are commonplace on account of their effectiveness in moving product through the various process stages, emphasises Karl Seidel, marketing director of US company Cablevey Conveyors.
“When transporting a blend of product with a conveyor system, maintaining a consistent mix ratio is essential, whether a fine powder, coarse mix, or larger variable-sized amalgams of different weights and shapes,” he comments.
However, conventional conveyor systems are not specifically designed to transport blends without changing the mix ratio. Various product material weights, sizes, and shapes can shift and disperse in open systems such as bucket conveyors, and vibration can cause the blended product to shift throughout transport.
“Vacuum and pneumatic systems can cause smaller lightweight particles in a blend to move at different speeds than heavier or larger particulates, resulting in significant blend restructuring when the product reaches its discharge point,” says Seidel.
Outputs produced can be put into business analytics tools, allowing [one] to visualise workflows through high quality data. That data provides early warnings of possible issues
Mark Lewis, regional director of bedding, The Vita Group
Tubular drag cable conveyors are engineered, though, to maintain precise blend ratios – one example being Cablevey’s completely enclosed, compartmentalised tubular conveyor system.
“Not unlike an endless succession of train cars, each space between solid circular discs holds a predefined volume of product. Based on the manufacturer’s specifications and requirements, engineers can calculate the optimal speed of the system, the most appropriate tube angles, and the proper construction design to guarantee their blended product remains consistent from input to discharge, even at high volumes,” says Seidel.
Tubular drag cable conveyors gently move product through a sealed tube using a coated, flexible stainless steel drag cable pulled through on a loop. Solid circular discs (flights) are attached to the cable, which push the product through the tube without the use of air. These conveyors excel in transporting delicate, precise blends for a wide variety of food types in versatile layouts and configuration.
Screw systems or auger conveyors, meanwhile, often use a helical blade to move granular materials within a tube. Yet this can cause product damage and compromise blends, so they are most effective when carrying items such as food waste, when material integrity is not critical, whereas tubular drag cable conveyors transfer material between two discs pulled by a sealed cable and are designed to protect delicate products and blends.
Manual handling remains, though, an enduring part of the mixing and blending process but for protein shake manufacturer Whitstable-based SMK Nutra Makers, pneumatics has enabled a more safe and efficient operation.
It switched dumping of a powdered chocolate mix from an elevated safety cage to floor level with the purchase of two Flexicon BEV-CON mobile, high-capacity flexible screw conveyors. Powder is now dumped at floor level into the hopper of a conveyor, which feeds a screener and, in turn, a blender.
Conveyors include a 7.5m long beveled-edge spiral, driven by a motor positioned beyond the discharge point, precluding material contact with bearings or seals. A pneumatically- actuated vibrator fitted to the hopper wall promotes the flow of powder, while a 3.6m high castor-mounted frame with support boom enables operators to roll the unit into position with the conveyor discharge directly above the screener, and then to a cleaning area.
SMK owner Avni Patel concludes: “Manual handling at floor level has increased productivity, eliminated dust, and improved worker safety.”
