Quality at speed
Torsten Giese of Ishida Europe discusses some of the latest developments in weighing and detection technologies.
The importance of accurate product weighing cannot be overstated. Apart from the legal requirement to produce packs at their declared weight, product giveaway – effectively giving the consumer free product due to overfill – is wasteful, particularly in today’s highly competitive markets. And unreliable and inconsistent pack weights can harm brand reputation.
Many confectionery products are difficult to weigh to a predetermined weight. The individual weight of sweets can vary considerably, meaning that a 100g pack can quickly go from being underweight (ie 90g) to overweight (ie 110g) by the addition of just one or two more pieces.
Therefore the confectionery industry was one of the first to benefit from the introduction of multihead weighers in the 1980s, which delivered pinpoint accuracy, greatly reduced giveaway and improved throughput.
The impact of this technology was significant. Product giveaway, which had been up to 10 per cent, was reduced to about one per cent and accurate filling meant packs could be smaller, reducing the cost of packaging, storage and transport. In terms of speed, even the earliest models were able to reach about 55 packs per minute (ppm). Today’s models can weigh at up to 400 ppm for single products and 60ppm for 6-mix applications.
Of even greater importance to confectionery manufacturers is the increased productivity that accurate weighing can bring. For example, product that was previously wasted in overfill can now be packed into additional bags. Output can therefore be increased without additional input.
Problem solving
Over the years, continuing devel-opments and enhancements have enabled multihead weighers to deliver even faster speeds and greater weighing accuracy. At the same time, many confectionery products have characteristics that make them difficult to handle during the weighing process. This has led to the introduction of features and application-specific multihead weighers that can deal with more difficult products. For example, special contact surfaces have been developed to enable sticky items such as jellies and gums to move freely through the weigher; and cushioning inserts and gentle sloping infeed and discharge chutes help to prevent fragile products chipping and breaking.
Another confectionery requirement that multihead weighers have been able to meet is the need for the mix weighing of products, where the weigher is split into sections to handle individual products at different target weights for discharge into one pack.
With the variety of different pack types available for confectionery such as bags, pots and jars, special distribution/filling systems also ensure an accurate, consistent and spillage free interface with the weigher.
Sánchez Cano is a Spanish manufacturer of gummy confectionery, marshmallows, liquorice, hard candies and bubble gum. At its factory at Molina de Segura, Murcia, it uses 12 Ishida multihead weighers to handle many of its products.
Chewy jellies come in a huge variety of shapes and sizes. However, for weighing and packing purposes, they fall into two main categories: oiled varieties, which produce a shine, or the more traditional sugar-sanded type.
Sugared jellies are relatively easy to handle and so the company uses 16-head double discharge multihead weighers, which effectively deliver the performance of two fast weighers in the space of one. Their flexibility also enables one side to be run while the other is being cleaned.
By comparison, the oiled jellies are much more inclined to stick, especially products such as ‘fried eggs’ or ‘rings’, which have relatively large flat surfaces. For this application, Sánchez Cano dedicates a whole weigher to each product, where the number of heads helps to make up for a relatively slow-moving product.
Among the weighers used for the oiled jellies are single-discharge 14-head weighers with anti-stick contact parts, including metal mesh in the hopper gates.
Glazed liquorice is comparable to oiled jelly in terms of stickiness. At Sánchez Cano, mixtures of liquorice candies are also weighed on 14-head weighers with special contact parts.
Marshmallows, dusted with sugar or cornflour, are handled on a 16-head double discharge weigher mounted over twin bagmakers, filling 500g and 1.25kg bags. The weigher has spacious three litre hoppers to accommodate this bulky product.
Sánchez Cano’s latest Ishida multihead weighers includes a 16-head double outlet model selected to fill resealable doypacks with chewing gum pieces. Chewing gum begins to lose moisture as soon as it is made, which means that harsh treatment could easily cause pieces of the outer coating to break off. For this reason, Sánchez Cano has selected an Ishida weigher with bancollan linings to reduce impact damage and the force of collisions.
Flexibility
The ability to adapt multihead weighers to manage particular product characteristics can allow confectionery manufacturers to dedicate machines to individual products. Nevertheless, weighers also have the flexibility to handle a variety of different products.
Hider Food Imports Ltd in Hull, UK, for example, sources and repacks a variety of nut kernels, dried fruit, confectionery and snack products from around the world, packing between 75 and 100 different product types into as many as 250 different size packs, ranging from 15g to 3kg.
To cope with this variety, the company uses 10-head Ishida weighers with interchangeable hoppers incorporating different finishes that are able to deal with the different characteristics of individual items, such as those that are sticky or more easily damaged. Equally important, changeovers can be carried out quickly and efficiently, with preprogrammed target weights called up on the weighers’ remote control unit.
While most multihead weigher designs are circular, a linear layout is also available and this can provide another solution for the gentle handling of certain confectionery products.
For products with brittle shells, such as dragées or chocolate-coated cereals, a fall of just 300mm can cause breakages or cracks. Therefore, an Ishida weigher at dragées manufacturer Coppelila features weigh hoppers arranged in a straight line, with drop distances minimised and crucial contact surfaces coated with shock-absorbing material. As a result, rather than falling, the dragées run downwards along a gentle 45° slope.
Multihead weighers help to maximise production throughput and efficiencies. At the same time, it is vital that the highest standards of product quality are maintained in order to preserve brand image and loyalty, and to secure valuable retail shelf space. Equally true, a product recall for any sort of quality or contamination problem can not only be extremely damaging in terms of loss of consumer confidence and reputation, the financial implications – including heavy retailer fines – can also be immense.
Quality control
Companies are increasingly taking a pro-active approach to quality control, putting in place systems that ensure that any potential quality or safety issues are swiftly identified and dealt with before goods leave the factory.
In these circumstances, x-ray technology is becoming particularly popular not only thanks to its versatility in identifying food contaminants but also for its ability to carry out an extensive series of quality control inspections.
In terms of contaminants, x-ray can spot a wide range including aluminium, tin, glass, stones, hard rubber, plastic, bones and shells, which makes the technology more versatile than metal detectors. Ishida x-ray machines, for example, can detect impurities that range from 0.3mm in size.
However, product quality is about far more than contaminants in a pack. Poor presentation, non-uniform product or incomplete packs can be equally damaging to brand reputation. This is where the versatility of x-ray is a major benefit. The technology can detect missing items in packs and spot deformed product and packaging.
X-ray can also carry out effective weight estimates and checks. And one of its advantages in this area in comparison to a more traditional weight check using a checkweigher is its ability to spot a problem that weighing alone could not detect. For example, if a pack is supposed to contain a set number of items of about the same size and weight but one piece is considerably over weight and one considerably under, then the total weight of the pack may still be correct but the end-consumer will not be satisfied with the overall pack contents.
Conclusion
The multihead weigher has already made a significant contribution to the growth and development of confectionery markets and its versatility means it is well placed to deal with any new product challenges in the future. The availability of x-ray technology will help to ensure that quality is never compromised in the drive for even faster weighing and packing.
