Key points
Factory managers are often to be heard saying that if they could design their plant from scratch they would lay things out differently. It’s a fact of life that as firms develop and grow, the constraints of maintaining production schedules as bits of new kit are added and others removed, mean that plant layout is often sub-optimal.
This means that production flows can sometimes be tortuous and it’s only when major factory overhauls and refurbishments are required that the opportunity is provided to review and revise the layout of factories.
Conveyor design (Return to top)
In most food and drink factories, what connects the operational manufacturing cells is the humble conveyor. Though a pretty ‘unsexy’ area, the smooth flow of work in progress between manufacturing operations and into stores is critical, though often taken for granted. And it's only when conveyors break down that their critical nature in providing the essential link in the internal supply chains becomes evident.
Those working in hygienic equipment design have long recognised that the good design of conveyor systems and use of appropriate components is imperative to minimise cross-contamination. This has seen the development of conveyor systems that minimise crevices and other places where the ingress of contaminants can occur, while facilitating easy cleaning between production shifts. In addition, materials used in conveyor construction have seen a lot of development over the years to further reduce the chances of cross-contamination while making them easier to clean down.
Campden BRI’s head of food hygiene, Dr John Holah, has suggested future factory designs might remove human sources of contamination entirely to maximise hygiene in food production. But he recognises that automation of production does not in itself eliminate the chances of cross-contamination. The reason, he argues, is that conveyor and robot gripper surfaces come into contact with food and this is probably one of the biggest sources of cross-contamination.
A solution, he says, is to redesign operations to minimise the number of contact points, while disinfecting robotic grippers and contact surfaces, using technologies such as electric shocks, localised heating or super chilling, ozone atmospheres and the use of adhesive/repellent surfaces for pathogens. However, these methods would probably require people to taken out of the equation, so are unlikely to be adopted extensively any time soon.
But that doesn’t mean conveyor layout couldn't be much improved using existing technologies. The latest conveyor design software called System Plast Engineering Calculator (SPEC), which is freely available from US engineering firm Emerson Industrial Automation, does precisely that by allowing optimal layouts to be achieved for chain and modular plastic, flat-top conveyors (visit PowerTransmissionSolutions for more ).
Built-in intelligence (Return to top)
The software, which received its debut at the recent Pack Expo show in Las Vegas, uses built-in intelligence to evaluate applications for steel or plastic chain and modular belt conveyors by validating detailed user specifications. Where possible, the software also presents an alternative optimum solution that may reduce energy or lubrication requirements with System Plast's novel Nolu-S wear material.
The process involves three steps: definition of conveying requirements, application requirements with product specifications, and system layout. SPEC software reports results that include required chain pull, motor speed, torque, shaft power and maximum line back pressure. The software issues alerts for incompatible parameter inputs during the process to help the user achieve successful results.
The software covers applications with carbon steel, stainless steel, several types of LF acetal for high-speed/reduced lubrication, and New Generation chain designed for high-speed dry running applications. Wear strip options include stainless steel, ultra-high molecular weight (UHMW) polyethylene, and Nolu-S self-lubricating UHMW for low-noise, energy-efficient dry running.
The claimed strength of SPEC software is its ability to translate the user’s input for product and system layout into a set of recommended conveyor components. The application definition allows inputs for variances of material, geometry, coefficient of friction, arrangement on the conveyor, type of conveyor lubrication, number of tracks, track pitch, speed, hourly throughput and more. Layout details include length, radii, angle, height, accumulation, and product load.
While SPEC is targeted at systems in general, another development aims to solve food losses on conveyors in the food processing sector.
Pop-up flight conveyors (Return to top)
The innovation from conveyor belt manufacturer Ammeraal Beltech, for which a patent is pending, is called the ‘Pop-up flight’. It is claimed to be a simple but effective modular solution to the age-old problem of products that have failed to discharge and remain on the belt on its return journey, and often then fall on to the packaging hall’s floor – something that is estimated to cost the industry huge sums of money.
“Our solution has been developed to stop these product losses, and make it easy for the processing or packaging firm to maintain high hygiene levels, without constantly having to sweep floors and hand-clean sticky belts,” says Graham Allen, global product manager for modular belts at Ammeraal Beltech. “The Pop-up flight is exactly what its name says. It pops up at the foot of the conveyor incline to support the food as it moves up the elevator, holding it steady. Then, once the product’s been successfully discharged, the flight pops down again so an automatic scraper can clean up the belt especially helpful for clingy food products.”
Pop-up flights, which the firm claims have been extensively field tested, can be retro-fitted to existing systems. Sirena Cold Stores, Denmark, is one example. “We needed a solution to convey frozen fish from the floor line to ceiling height,” says Tommy Pedersen, Sirena Cold Stores’ md.
“Normal solutions such as a flighted incline conveyor were not possible the fish freezes to the belt and has to be scraped off at the discharge point. Ammeraal Beltech’s Pop-up flight is a brilliant but simple solution. We have a shorter conveyor with a steep incline so the product doesn’t have time to defrost during transportation and we have eliminated potential food loss due to multiple belt transfer points. Plus, we can still scrape the belt.”
With existing factories, new conveyor systems are more usually installed when it is a production requirement. Such was the case with west country bakery Tamar Foods, which bakes own-label pies, slices and snacks for the multiples. These are distributed by sister company Ginsters.
Last year, Tamar won a contract with Marks & Spencer (M&S) to produce a range of savoury pies. Tamar’s conveyors had to be able to handle M&S’s green totes – something Tamar’s existing 12-year-old conveyor system couldn't do.
The old system was installed to take products from the packing hall to the Ginsters dispatch hall, via a 160m-long tunnel joining the two buildings. The conveyor’s path was somewhat tortuous, twisting and turning its way along, up through the roof and then back down to the dispatch carousel. It was extremely noisy, unreliable, and difficult to maintain.
To meet the terms of the M&S contract Tamar installed Axiom GB’s poly-v belt driven roller conveyors and belt conveyors using an aluminium profiled side frame.
“The new system not only had to handle the M&S totes, but also our own cardboard cartons which vary in size and shape,” says Steve Towsey, Tamar’s project engineer. “In addition, we wanted it to have an accumulation capability. The old system didn’t have this and with our very high throughput rates it caused endless problems. An issue anywhere on the system meant we had to stop the entire line, which led to product piling up and high levels of inefficiency.”
Axiom’s accumulation system featured zero line pressure control to avoid any product damage.
The conveyor system is fed from three packing stations two manual systems and one fully automated packing machine. The packers can pack up to 77 totes a minute, which the system has to merge and convey from the three packing areas. To supply the packers with a constant feed of empty totes, Axiom designed an overhead tote delivery conveyor which transports totes from a holding area to the packing face.
A combination of packed totes and cartons join over a series of merge conveyors onto one conveyor that twists and turns its way up a series of inclined belt conveyors into the roof void. The conveyor passes through the long tunnel where a series of roller conveyors queue product for delivery to the dispatch hall.
“Although the system operates 24/7, it has been designed to ‘go to sleep’ when there are no products on the conveyors,” says Towsey.“This means that ,as well as getting savings from low- maintenance requirements or downtime, the new system delivers excellent energy savings.”
Intersnack spiral (Return to top)
In another example of novel design to accommodate factory constraints, Astec Conveyors designed and installed a high-level case conveyor system for Intersnack.
Previously, cases were palletised manually at the end of each production line, and then transferred by pallet truck some 50m through a busy operational area to the warehouse.
As the area in the packing hall was restricted, Astec designed a system to automatically merge different case sizes from the various production lines into one single line, using zero line pressure zone controlled powered roller conveyors.
Due to restricted space, Astec introduced a spiral conveyor to provide continuous, smooth vertical transfer of product to a high level. The spiral feeds onto a high level powered roller system to the warehouse, eventually declining down a belt conveyor onto a gravity roller section for manual sortation and palletising.
As a result of the installation, both labour cost and pallet truck operation in the packing area through to the warehouse has drastically been reduced, while also addressing and eliminating several safety issues.
Both these examples demonstrate the need for lateral thinking to make the best of production layout constraints. Given that most managers will not have the luxury of being involved with new builds, such innovative solutions will be the answer to many problems.