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Getting to grips with product giveaway

10 April 2022

Suzanne Gill reports on the vital role that modern checkweighers have to play in helping reduce product giveaway to an absolute minimum. 

With our industry reporting a six-year high in food prices at the start of 2021 – a figure which only looks set to continue to rise with ongoing supply chain issues and conflict in Ukraine – it is imperative to reduce product giveaway to ensure less waste and to enhance productivity.

Giveaway has been a long-accepted practice in food factories, and now is a very good time to prioritise its reduction with the help of modern checkweighing systems.  

Production lines which rely simply on regular samples being weighed off-line to comply with legal requirements are checking only a very small percentage of production to represent average weight. Minebea Intec has undertaken customer trials which shows that a reliance on such a sampling strategy will result in giveaway figures that are often much higher than expected. Peter walker, sales manager UK and Ireland at Minebea Intec, said: “You may think you are only giving away 0.5g to ensure  minimum weight compliance but when this is analysed across 100% of production that figure is often much higher, which means that companies can be giving away more than they think. Further, the products may not actually be compliant with the regulations.

“We have found that in some industry sectors – such as cheese and confectionery – return on investment (ROI) in a checkweigher is typically less than one year. It has the additional benefit of freeing up operators to do more valuable work than weighing sample products off-line on multiple production lines.”

The addition of an in-line checkweigher to the production line will immediately ensure that 100% of production is being weighed and it also introduces the ability to reject out of specification products and alert operators to the fact that the filling machine may need to be adjusted to allow companies to aim as close to the nominal weight as is practical. “This becomes possible because with an in-line checkweigher you are no longer guessing whether just 0.1% of production is actually a true representation of total production.”

Walker says that, once installed many checkweigher users will quickly go a step further – allowing the checkweigher to control the filling machine. “The weighing technology employed by Minebea Intec gives a repeatable and accurate result giving the best opportunity to continually check the accuracy of the filler – the checkweigher is able to automatically adjust the filler to keep accuracy to within 10ths of a gram of the nominal weight,” he said. 

With the checkweigher positioned immediately after the filler or cutter on the production line it is able to quickly pass information back down the line to ensure accurate adjustment of filling/cutting operation to ensure weights remain accurate. “This operation is a continuous process which samples, say 20 packs to check the average weight, then the cutter or filler is automatically tweaked to get closer to the nominal figure and, when the first affected pack makes it to the checkweigher, the process repeats,” continued Walker.

He went on to explain that the data collected by the checkweigher can offer huge additional benefits. “Using data capture software it is possible to record and store weighing data to ensure that all legal and customer requirements are being met and that reports are instantly available whenever they are needed.

“Checkweighers should offer a variety of connectivity options so that they can be connected to existing factory systems, if the technology is there already. Minebea Intec, for example, can provide software created specifically for the collection of data from checkweighers which stores all the checkweigher data needed to help create reports and allows organisations to better understand their production lines.”

Eliminating deviation
While the primary role of a checkweigher is to ensure that a product conforms to its claimed packaged weight at all times. Ishida also pointed out that its ability to assist with the notification and correction of weight issues caused by processing equipment can offer huge benefits.

Today, advanced software systems, such as Ishida’s Data Capture System (IDCS) enable checkweighers to notify operators and planners when product weights are deviating against their reference value. This can allow a faster response to making corrections to the process in order to prevent overweight or rejected product.  

Ishida offers a feedback control loop from the checkweigher to the upstream dosing or filling system to automatically adjust the filler to ensure minimal giveaway.  “The characteristics of some products can alter during the production run – bakery products, for example, can lose moisture and become lighter. When such changes are identified by the checkweigher, the parameters of the depositor or filler can be adjusted to further improve the accuracy of each weighment,” said Philip Grove, product manager – Checkweighers, Metal Detectors, IDCS at Ishida Europe.

Offering an application example, Grove said: “Weight information on a chocolate bar could highlight that it is consistently 2g over the required weight. This may suggest that the enrober is putting too much chocolate on each bar. For a ready meal or a bag of mixed nuts, the same overweight each time might identify a particular ingredient that is being added in too high numbers. IDCS is able to demonstrate weight trends of the production batch; adding in a correction system to the upstream process such as feedback control will assist to provide tighter control against weight inconsistency.” 

Grove goes on to point out that continually excessive weights could also indicate that the line is running too fast for it to deliver maximum efficiencies. “Giveaway is amplified by the amount of product going through the line. If by lowering the overall speed, the amount of giveaway is significantly reduced, this would ultimately deliver a much better overall efficiency rate,” he said.

“With IDCS all the data that the checkweigher is able to generate is instantly available and accessible – it does not require the information to be downloaded and then manually assessed in order for a report to be compiled; and remote access means information can quickly be compiled and compared between different lines, even at different locations. Automatic notifications can be set in the event of under or over limits being reached. 

“This allows users to take instant action to improve the performance or efficiency of their lines, so much so that payback on this investment can be extremely fast.”

Grove also pointed out that data derived from a checkweigher can provide a constant and real time health check on all areas of the production line. “If a company does not know how well it is performing at any particular moment, then it will be impossible for it to make adjustments or improvements. Equally important, accurate comparisons can be carried out between different lines. This can be valuable where the lines are in different locations; using the checkweighers to supply and interpret the data means everyone is working to the same standards,”

An optimisation tool
According to Mark James, general manager of sales at Yamato Scale Dataweigh UK, a common dilemma that plant managers are experiencing today is how to continue to expand or optimise their production lines while guaranteeing high quality output, compliance to industry standards and controlled costs. “In almost every scenario, the answer is to instal a checkweigher to support production,” he said. “This extends across every sector, with our clients in the confectionery, fresh, meat, frozen and dairy sectors having achieved improved results by incorporating checkweighing processes into their production.” James goes on to point out that a checkweigher can enable maximum accuracy and eliminates the danger of under or overweight products – the first leads to customer dissatisfaction and non-compliance to trade laws, and the second can result in excess waste and cost inefficiencies.

“With disruption affecting supply chains across the world and the cost of supplies increasing, using only what you need and not overfilling lines will dramatically affect your finances and ability to meet demand,” continued James.

Working in tandem with other inspection equipment – such as metal detectors and x-ray machines – checkweighers can safeguard products against contamination and other faults as part of a more stringent quality control strategy. “Most crucially, checkweighing can unlock a myriad of benefits for your plant: including reduced risk of costly product recalls, better management of supplies and cost-efficient processes,” he concluded.

Communication is key
According to Mettler Toledo, the key to reducing product giveaway in the food processing sector is to achieve greater weighing precision within the production line. It says that when precise weighing capability is linked to machine-to-machine communication, to enable automated adjustment of filling systems based on the weighing results, then food processors are more accurately able to control product giveaway, as well as improving productivity. 

Mettler-Toledo’s FlashCell-equipped checkweighing systems are designed for exactly these production line scenarios. These load cells  promise short measuring times, can weigh food products at speeds of up to 800 parts per minute (ppm) with no compromise on either weighing accuracy or operational performance.

In terms of precision, installations of this Mettler Toledo technology at customer sites show that the load cells deliver weighing results with a standard deviation up to four times lower than its previous generation of EMFR load cells. Even at speeds of 800ppm, they are said to be capable of precision weighing to a level that is better than the standard required by the EU’s Measuring Instrument Directive (MID) for a 35g cereal bar and in accordance with OIML R51 and R76 (International Organisation of legal metrology) for pre-packaged goods.

All this means that the checkweighers can offer productivity gains, in addition to more accurate fill levels to minimise product giveaway. Their ability to communicate information along digitalised production lines is also a bonus. It allows them to automatically adjust and correct the output of preceding production machines or filling systems where necessary, eliminating both under- and over-filling at source. 

This is not just about monitoring production lines argues Mettler Toledo. It is about actively optimising them. In a networked environment, dynamic checkweighers can carry out proactive device management – for example, by transmitting centrally-maintained limit values to many weighing systems at the click of a mouse, rather than configuring each system locally. Another example is evaluating status messages of weighing systems centrally, in order to optimally plan maintenance work and avoid downtime. 

Through interventions and optimisations such as these, a checkweigher can also help improve a production operation’s Overall Equipment Effectiveness (OEE) rate, which describes the productivity and efficiency of the production line. This is made possible by capturing real-time data and providing indicators where best to improve production processes. 

Working in harmony
Phil Brown, managing director of Fortress Technology, believes that there huge untapped potential for the utilisation of automation and data collection at this critical point in the food production process and he says that investment in modern checkweighing equipment will allow greater efficiencies to be achieved through the use of network techniques. “With high-speed communication technologies – such as secure Ethernet, capable of integrating checkweighers into groups – results can be pooled across multiple lines of identical product groups and pack sizes to calculate an average batch weight,” he said.

“Consider the checkweighers as being part of a finely-tuned orchestra,” said Brown. “A group of checkweighers with Ethernet connection can process identical products and packages and be regarded as one line for the purposes of weight control. For example, if one system has an average weight below the declared quantity of a product, taken alone the checkweigher would have to reject packs to bring that average up, subsequently increasing giveaway, whereas virtual checkweighing allows machines to be complemented with another unit and broadcast the overall average weight so far in the batch. Concurrently, it listens to the broadcasts via an Ethernet local area network from the other units of the same group. The checkweigher then calculates the average weight of the group and automatically decides whether or not to reject each pack based on overall performance. The result will be a reduction of unnecessary rejects and subsequent wasted product.” 

In conclusion, Brown said: “With the market estimating the cost per line of false rejects at over £11,000, reducing giveaway by using efficient software is an essential step for factories looking to cut costs and improve bottom line savings.”

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