Bacteria get a good belting

Conveying enjoys the kind of standing that, on a national level, is normally reserved for public transport. After all, neither is anything more than a system from getting from A to B, and both are seen as necessities rather than something that will add particular value to an operation.

But increased scrutiny of hygiene levels has meant that, like all other types of equipment, conveyors have had to be reassessed as potential hazards for all food and drink companies.

"From our conversations with the food industry, I would say that people are far more willing now to spend more money on hygienic solutions in conveying," says Sweden's FlexLink Systems product manager Sven Axman.

While the use of stainless steel is equated with the highest hygiene levels for most other types of food-grade equipment, plastics are the most common material found in conveying – at least as far as the belt is concerned.

This is because of both the high cost of creating the intricate type of sections used on modern food conveyors in stainless steel and, increasingly, because plastics can be made tougher and more microbially resistant than was previously the case.

According to Mr Axman, independent tests carried out in Sweden have shown the newer generation of anti-bacterial agent to be highly effective in a food production environment. The agent can be mixed with the polymer prior to the moulding of the belt and will then actively slow down the growth of bacteria on the conveyor.

Manufacturers can now source plastics belts that are just as hygienic as a more costly steel equivalent, he says. Combinations of different polymers are now used in creating harder-wearing belts with greater impact resistance.

While belt manufacturers are talking up the importance of anti-bacterial options, for others in the industry they are just an additional weapon against contamination in an already well-stocked armoury.

CKF Systems specialises in handling and conveyor systems for the pharmaceutical and food industries and, according to Heather Witts who is responsible for sales and marketing, this means that hygiene has always been at the top of the priority list.

"The hygiene aspects of our kit have always been there," says Heather. "Repeat work for major food companies such as Cadbury, Nestlé and Mars means, for example, that we know their very high standards extremely well.

"Anti-microbial belts are something that people are starting to pick up on but they're still a long way from being on their list of demands. Certainly, we've never had problems before where we didn't use this sort of belting."

CKF constructs the mechanics of the conveyor but sources belts from other suppliers. The more high-profile anti-bacterial systems, Heather Witts points out, includes one from Rexnord which contains Microban.

FlexLink has carried out research with customers such as dairies, and the feedback shows that ease of access for cleaning is frequently the most important consideration for end users. The supplier is making clean-in-place and sterilise-in-place systems already used in the dairy sector available to other hygiene-conscious customers.

"We have come a long way in developing this, and we are looking forward to introducing a CIP system later this year," says Sven Axman. "It should dramatically reduce the need for taking the chain from the conveyor." Under normal circumstances, this requirement will vary considerably, he explains, depending on the product type.

The CIP option is being built into the hygienic conveyor that FlexLink launched at Interpack earlier this year. The working part of the 100m/min conveyor runs on stainless steel sections that can be connected using a system that avoids the need for welding. This is important, says Mr Axman, given both the hygiene and cost implications.

"When welding, the edges have to be ground carefully as there can be gaps in the weld. In the food industry this can be a concern for hygiene reasons," he says. Flexlink is patenting its weld-free system which, he adds, is cheaper and constitutes the most stable alternative.

The most important surfaces from a hygiene point of view are clearly those of the conveyor belt itself. The most recent launch from Intralox – the 1600 open hinge flat top belt – has a sculpted underside with radiused corners said to prevent scrap and particle build-up.

The PP, PE and acetal belt is also designed to give high water flow rates, says the manufacturer, and so speed up the cleaning process.

According to Intralox, the 1600 becomes visibly clean in less time than any other 1in pitch modular plastics belt.

The hinge openings are large enough, says the company, to allow spray to reach both top and bottom surfaces during the wash down process.

Like the other direct-food-contact additions to the Intralox range launched this year – the 800 open hinge flat top and 1800 flat top belts – the 1600 has a drive bar on the underside of the belt which pushes water and debris to the sides for fast and thorough cleaning.

The 1800 was introduced as a solution for the meat and poultry industries, with their particular demands for high sanitation levels combined with good impact resistance. Again, Intralox claims that tests on the 1800 have shown it to be the belt on the market with the highest impact resistance.

Customer feedback told FlexLink that having a protected return conveyor was another key concern in a food environment. On the company's new system, the returning chain runs in a shielded guide section beneath the portion of the conveyor in use.

This means that, if there is a spillage on the line, it will not contaminate the underside of the belt and so makes cleaning a much easier and more localised affair says Mr Axman. Another requested feature currently under development at FlexLink is automatic guide rail adjustment. Like anti-microbials, this is an area that different conveyor suppliers are starting to move into. In this case, it has been prompted by the trend towards shorter runs of different products.

At a certain frequency of changeover, savings outweigh costs incurred by a relatively expensive automated system in time but Mr Axman is the first to admit that this will not be suitable for all types of operation.

For customers interested in total solutions, he says, intelligent PLC systems and servo drives will allow operators to ramp line speeds up and down, providing better handling for product.

Finally, there are other types of conveyor used in the food industry where, by definition, equally stringent hygiene considerations apply.

One example would be Guttridge's Multiflo tubular screw conveyor, which is used to elevate powders to the height of process or packaging machinery hoppers.

Whether belts are for direct contact with food for handling product already inside primary packaging, the hygiene principle remains paramount. This may mean responding to the practical and visible wash down needs of a line dealing with fresh meat.

It may also involve addressing ever-increasing concerns about invisible contamination, the risks of a public health scare and the damage that this can cause to a brand, a retailer or a complete product category.

While interest in anti-microbials is likely to grow, it will not be at the expense of other aspects of belt and conveyor design.

Increasing attention is being paid to fast-draining, open belts with protected return belt options, self-draining areas below the top belt, easy access, and CIP and SIP options for high-frequency cleaning.