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Top quality drives means top quality fruit conserves

30 July 2010

Quality or quantity? The owners of Aarts Conserves had to make this decision some years ago when they determined their vision for the future. They went for quality, positioning them at the high end of the market. An unsurprising decision given the solid position they had established over time.

With a reputation for high quality canned and bottled fruit products, Aarts (from North Limburg in Holland) decided last year to overhaul its entire production process. In particular, the preserves packaging line was due some major updating. Harold Cornelissen, Head of Technical Services at Aarts, explains: "We had a production line here where neither power nor the PLC control system could cope with increasing production demands. Over the last 10-15 years there must have been four different brands of frequency converters installed, some of which are now obsolete and no longer supported. The PLC was showing its age too. Some of the parts are no longer readily available, or only at a premium. Most importantly, reliability was very much in question. Most of the fruit comes to us fresh from the field. From April onwards we need to run for months on a continuous basis. We cannot afford downtime, as you can imagine”.

Radical solution
Twan van der Aa, Account Manager for industrial automation company Hotraco Industrial in Hegelsom, adds: "We immediately advised opting for an industry standard control, because the worst thing that can happen to a business is to be dependent on a single supplier. Our proposal was to migrate to a Siemens S7 PLC-control for the total control of the production line. That gives Aarts a solution which can be supported by a number of specialist companies. The old power transmission created enormous EMC problems, so we came up with a radical solution. Several data cables were suffering from environmental emissions emitted by the old drives. It was obvious to us there was only one way forward; complete replacement of all the old drives by EMC-compliant units from Danfoss. That was very important for us, because despite the new control system we had the problem relating to EMC-pollution which we would never otherwise have been able to cure.”

EMC-problems
Hotraco Industrial BV installed frequency converters for the control of the conveyor belts, using. Danfoss FC302 drives. These drives are equipped with high torque boost facility to overcome “stiction” at start. Just as important is the EMC-immunity of the frequency converters. In the original installation there was frequent failure of the Ethernet link due to interference on the cable running through the production areas; choosing fibre optic cables partially resolved this problem. EMC-related problems really do need an integrated approach. Good-practice installation is critical for effective prevention of EMC problems. Correct earthing and use of shielded cables are essential. Just as important is the potential source of interference, which includes some frequency converters. With the installation of the FC302, Hotraco has succeeded in eliminating future problems for good, since they avoid EMC-related problems thanks to the integrated RFI filter. A wise decision, given that in the production area at Aarts a motor cable can run for more than 100 metres. The integrated filter, combined with correct earthing of both the cable and the mounting plate in the control-panel ensures that problems with EMC and low harmonic currents are eliminated. A major part of correct installation is to ensure that screened cables are connected directly to the connection point and ensuring there are no “pigtails" which can act as radio-frequency antennae. It is all about good-practice installation.

Fresh from the field
Any company involved with processing fresh produce is at the mercy of the growing seasons. During the relatively quiet winter period, pears are imported from Mediterranean countries and packed in large tins for the hospitality and catering trade. But in the spring, within a very short time, vast quantities of cherries and asparagus come in from the fields and orchards. The asparagus in particular, which is widely grown in North Limburg and parts of Brabant, creates a lot of work. All products are peeled immediately on arrival at Aarts and then placed by hand into the jars. The recipes which are used are mainly based on old traditions which date back to the time when many farmers’ families would preserve their own fruit in air-tight jars. Over the spring and summer period, two shifts are worked and the production barely stops. Other products which Aarts processes are mushrooms, peaches and plums.

Customer-specific production
A sizeable part of Aarts' production is customer-specific, which means, among other things, that the jar has a special shape with dedicated label.
When a product change is needed, Technical Services need to reconfigure each part of the production line to suit each type of packaging. Aarts has to deal with 137 different glass jars and cans including many exclusive packaging styles. All of these containers travel along the same production line. One part of setting up for a different type of container is adjusting the speed of the line, because the taller and narrower the jar, the easier it falls over. Hotraco developed menu-structured software as the solution. In the Step 7 programme, sections have been created where the Head of Production at Aarts can choose a given recipe for each type of packaging. "Usually we change the recipe twice a day; but sometimes there can be five changes. A complete set-up now takes between 15 and 20 minutes. After that, everything is adjusted, ready to go. In our experience that is really quick."

Ethernet
Aarts Conserven is now thinking about phase two, when the company wants to extend production control using Ethernet. The new control system already communicates using Profibus. Using Ethernet Aarts wants to create an infrastructure which makes it possible to log the temperatures of the pasteuriser and cold stores efficiently. Logging of this type is extremely important for Aarts because of the certification and quality guarantees of their products. A secondary requirement of the Ethernet is to provide Aarts with comprehensive energy consumption data, because their process is energy-intensive. As the company wants to minimise energy consumption, it needs to have data about the actual production process. With industrial Ethernet it is possible to collect data from multiple sources and make it accessible for analysis.

Conclusions
Harold Cornelissen, Head of Technical Services at Aarts: "We place heavy demands on every aspect of our production. The control system has to work properly and if there is something wrong, we need to be able to fix it ourselves. That is what we achieved. I can also switch to a manual override on the control software. The parameter settings for the drives are stored on a laptop and with MCT10 (Motion Control Tool) we can change them ourselves. MCT10 is freeware from Danfoss. But if I can't sort it straight away, then we need rapid service. Hotraco are just 5 minutes drive away. They hold numerous Danfoss drives in stock so in the event of a failure, they can offer a direct replacement. Our partnership with Hotraco is incredibly important to us. We only have a small Technical Service department of two people. Most of the year we can keep pace, but in the high season we are often running two shifts. Then any repair requirement means working under extreme pressure. Good, local support is a must." And the drives themselves? "These are extremely high efficiency and only need minimal cooling. The ambient temperature here can easily climb to a good 30 degrees with extremely high humidity. But almost no heat is given off by the drives. The energy consumption is certainly lower, but exactly by how much we don't know as yet."

Partnership
What is the background to the partnership between Aarts and Hotraco? Harold Cornelissen: "Even though they are just down the road, we didn't really know each other. They had sorted out a bug once in our old control system, but that was it, until two years ago when we went looking for local service. Then we teamed up with Hotraco. They offered us just what we needed; prompt, local, expert service. In the end this project grew out of that relationship. We did of course get competitor quotes, but in the end we decided to go with them. What convinced us was not so much price, but their commitment and advice. We communicated frequently with each other, had a lot of discussions. Availability is an important thing in a partner. They are close by and are always contactable, 7 days a week, 24 hours a day. We want at least 10 years of trouble-free running and they offer good components for that." Twan van der Aa, Hotraco: "The collaboration around this project was indeed intensive. From our side we offered a lot of options, and what is nice is that they went for all the options. The final installation was very quick. It was really an integrated operation. The whole floor had to come up, take all the cables out, but it all worked first time. We switched on and started production immediately. In fact, we only fine-tuned for half an hour at most. The partnership carries on; we are now busy looking at Ethernet options."

For further information contact:

Danfoss Ltd
Capswood
Oxford Road
Denham
Buckinghamshire
UB9 4LH

Tel: 0870 241 7030
Fax: 0870 241 7035
Email: uk.controls.sales@danfoss.com
Web: www.danfoss.co.uk
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