The Multihead Weigher - A Stalwart On The Packing Line

Ongoing advances in multihead weighing technology continue to equate to big gains in giveaway reduction and efficiency levels

The multihead weigher has become something of a stalwart on the packing line these days, delivering high speeds and accuracy to help meet production targets and keep both customers and end-consumers happy.

Ishida’s invention of the multihead weigher in Japan in the 1970s and its launch into Europe in the 1980s were undoubtedly major game changers for the food industry, and the confectionery and biscuit sector in particular; certainly, the reductions in product giveaway that these early models achieved, especially with delicate biscuit items, were truly jaw-dropping. Nevertheless, while the latest weighers may not be able to deliver such headline achievements, the continuous improvements that have been made to multihead weighers over the years mean these models are still having a huge impact on many companies’ bottom lines.

Image 1: Multihead weighers are ideal for mixed confectionery packs, weighing different products simultaneously for discharge into the same pack

Indeed, while the principle of multihead weighing has remained the same over the past 50 years, what the weighers can deliver has come on in leaps and bounds. The many incremental improvements and enhancements that have been introduced during this time continue to deliver extremely impressive savings.

This is important because product giveaway remains a major concern for many food manufacturers. In our recent customer survey over half the respondents cited this as still being their biggest weighing challenge, and that a reduction in giveaway represented the best chance to create extra value within the business.

Taking one example from our own installation base, the replacement of a confectionery customer’s existing Ishida weigher with a brand-new model further reduced product giveaway by 0.5g and increased overall speed by 10 packs per minute. These relatively small improvements equated to an annual saving of 450,000 euros and led to payback on the machine being achieved within six months.

Maximising value creation has been a key part of the ongoing development of multihead weighing technology. Over the years numerous models have been developed for specific applications, very often for products that previously had been considered too difficult to handle in an automated weighing system – in the biscuit and confectionery sector these have included sticky and sugar-coated items, such as jellies and gums, and fragile and brittle products. For the mixed and variety packs so popular in the confectionery sector, high head weighers with 16, 20, 24, 28, 32 and even 36 heads can mix up to eight different products simultaneously for discharge into the same pack.

Ongoing advances in multihead weighing technology continue to equate to big gains in giveaway reduction and efficiency levels, explains Neil Wightley, Ishida Europe Multihead Weigher Business Manager

There have also been many design enhancements throughout the machines, focused on improving product feed and control, and simplifying and speeding up routine operations such as changeovers and cleaning.

This close alignment between weigher and product brings several benefits – a reduction in operating costs and increased production efficiency, and better utilisation of the machine to drive improved quality and reduced risks.

Equally important, these enhancements have been supported by numerous software developments. Particularly significant is how the software has evolved from merely controlling the weighing process, to also including data capture, monitoring and reporting. This is especially vital as processing and packing lines have become increasingly integrated, with equipment linked together to provide a faster and more efficient operation.

As the saying goes ‘knowledge is power’. Being able to easily access a line’s current status and quickly analyse the data provided creates the increased visibility that enables lines to be kept running at maximum performance and efficiency since small issues that might be slowing down the line can be identified early and dealt with immediately.

Image 2: Quick access to and fast analysis of line data maximises performance and efficiency

Similarly, these advances in software have also allowed weighers to self-optimise. For example, product flow can be regulated to ensure a consistent amount to all hoppers. Head optimisation is used to ensure that product does not stay in a hopper for too long.

Alongside this, the operation of the weigher has been made even more user-friendly for line personnel. In particular, information screens have become more intuitive, further speeding up machine set up or problem solving. A multihead weigher will continue to operate quite happily with one weighing head out of action, but the loss of this head halves the number of weight combinations available for each weighing cycle, which quickly adds up to a big drop in overall efficiency. Such a problem can now be instantly flagged up for operators to take remedial action.

This combination of relevant data and advanced software can have a marked effect on efficiency levels. Whereas earlier multihead weigher models offered rates of around 95%, these can now be increased to closer to 99% on current weighers. Even more important, such a rate is being achieved far more consistently.

All technologies evolve over time. The first mobile phones were a revelation in their day, and while many will continue to work perfectly well, they lack the majority of the features of the latest smartphones. Unlike the evolution of the mobile phone, multihead weighers may not have changed that much in terms of looks, but certainly the technology that drives them has continued to advance. Today’s models for confectionery products have kept pace with the market they serve, helping to cope with increased competition, meet and anticipate new trends, and respond to ever-changing consumer demands and retailer requirements.

For confectionery producers, therefore, staying abreast of the technology can deliver significant benefits, as the weighing industry continues to push the boundaries of what multihead weighers can achieve.