Reducing waste and improving productivity

04 December 2017

Daniela Verhaeg explains how developments in product inspection systems can contribute to waste reduction and help to improve productivity in bulk food applications.

Product inspection is an essential part of delivering a high-quality product. However, this critical process can also contribute 'acceptable' levels of waste; in terms of lost production time, lost product and consequently lost income. While the primary purpose of product inspection technology is to ensure that the product reaching the consumer is compliant and contamination-free, there is an increasing awareness among system builders that this should be achieved with minimal impact on the user’s bottom line.

Time is money
Unscheduled and unnecessary downtime is never good. With schedules often tight every stoppage represents lost production time and the potential for knock-on problems elsewhere. A line that is not operational is not earning money, and there are several elements that could be contributing to reduced margins.

The frequency of routine tests for product inspection equipment, particularly metal detectors, is one example of where 'acceptable' downtime can be improved. While regular testing cannot be avoided altogether, one way to minimise downtime in high volume, dry product applications is to use systems with ‘Reduced Test’ Mode capabilities. This mode monitors system performance to ensure a metal detector is working to, or better than, the customer's required standards. The parameters are set higher than required in order to alert line operators to potential issues before they reach unacceptable levels. 

Reduced Test Mode therefore has the potential to save time and money. A typical test frequency using standard metal detection is around 12 times per line per day – though depending on product type it can be as high as 20 times.  Reduced Test Mode shrinks this requirement to two tests per day (subject to quarantine periods). Assuming that a normal test takes around three minutes, that's a saving of 30 minutes production per line, every day. In other words, the frequency of routine testing can be reduced by up to 83%:

Indeed, any measures that reduce downtime or increase throughput will have an important cumulative effect. Inspecting 100% of product inline is an advantage: but not if the inspection equipment becomes the bottleneck in the process. Improvements in speed and detection sensitivity in the latest generation of metal detectors and X-ray inspection systems ca help improve productivity for food manufacturers.

Cutting your losses
In an ideal world, 100% of materials would make it through the supply chain; but some waste is inevitable. From a product inspection perspective, the process of removing contaminants involves creating waste, so it is important to minimise this.

Bulk X-ray or metal detection systems installed at the start of the production line means that incoming ingredients can be inspected immediately, with any contaminants removed early in the process. This prevents loss of product further down the line and can also prevent damage to equipment, especially where the contaminant is a hard material. Removing contaminants before further value has been added during processing and packaging also saves money.

Traditional product inspection reject devices were often designed to remove a full belt width of product when a contaminant was detected, rather than targeting the specific location of the contaminant. A full belt width contains a large percentage of good, useful product. While this may have the potential to be reworked once the contaminant has been removed, the cost of rework is often greater than the cost of simply discarding it. 

Today, solutions such as X-ray inspection systems for bulk products feature improved reject mechanisms that help to minimise product waste. One such example is a multi-lane scoop reject device, which accurately rejects only the area of the belt containing the contaminated product without removing excessive good product. Likewise, multi-lane air blast rejection devices can remove a smaller, more targeted section of product on the belt – limiting waste. Some systems are now so accurate that they can pinpoint and remove an individual non-conforming burger patty from a free flow process at production speed.

For product that has fallen from a conveyor, there is no rework option. This will simply be wasted and may contribute to downtime if it has to be removed from the vicinity of the line. Troughed conveyors help to significantly reduce this issue. Designed specifically for bulk applications, they are developed to prevent product spilling from the line. This form of conveyor also ensures that product is presented at a constant depth, which enables product inspection to be optimised. 

There are other ways that product can be lost. For example, high value fine powders can escape into the reject channel in gravity-fed systems. Incorporating dust-tight seal technology in gravity fall metal detection systems can resolve this problem. Also, the use of infeeds tailored to a specific application will ensure product is not lost during transfer to and from the inspection system. 

False rejects?Last but not least, false rejects – where contaminants are identified by the detector but not actually present – can contribute to an increase in wasted good product. Enhanced software algorithms can minimise these occurrences, increasing accuracy and allowing X-ray and metal detection systems to reject various products at high speeds, while still ensuring the detection and removal of contaminants such as metal, glass, dense plastics, mineral stone and dense rubber.

A combination of advanced product inspection software, checkweighing and metal detection product inspection has recently enabled a dairy producer to achieve significant reductions in product waste. 

Heinrichsthaler Milchwerke GmbH produces 200 tons of finished dairy products a day on 12 production lines. An integrated HACCP approach facilitates responsible production methods. Five combination checkweigher and metal detector systems have been installed to form critical checkpoints behind the thermoforming and tubular bag machines. Approximately 7,000 products per hour can be checked by each inspection system, with up to six product changes required on each line.

The product inspection software enables the company to monitor and optimise the mean values of the packaging weights, while real-time proactive data helps to avoid costly overfilling. Since its inception, product waste has reduced from 3% to only 0.9%, immediately saving 2g per package. Consequently, investment in the product inspection technology paid for itself within three months.

In conclusion, product inspection systems may be a ‘must have’; but any associated waste of time, product or money, however ‘acceptable’ this may have been in the past, should not go unchallenged. Inspection system manufacturers are continuously working to find better ways of supporting food processors in their goal to improve productivity, reduce waste and safeguard profitability.

Daniela Verhaeg is marketing manager at Mettler-Toledo Product Inspection.

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