Is it possible to get milk straight from the cow and into the glass? That might be feasible on the farm, but consumers in the city still want their milk just as fresh. Achieving this requires quick filling and packing. The automation specialists at Advanced Machine Company AS (AMC), Vestfossen, Norway, have developed packing lines that can stack almost 30 different versions of filled milk cartons in containers. This small company has earned a reputation as a major systems supplier to the Norwegian dairy cooperative.

“The rising capacities of modern filling machines require faster handling of the cartons once they’ve been filled. This is particularly true for milk—a completely natural product,” said Harald Hals, CEO, AMC. “This means we have to be very flexible and reliable in our work. We expect exactly the same from our suppliers as we search for solutions and the shortest possible delivery times for high-quality components.”

Seven hours less work
The most recent success story at AMC stars new packing lines for a dairy plant. It places milk cartons into the individual rates situated in roll-in containers. Those cartons are then ready for dispatch to shops, companies and schools. Compared with previous systems, which could fill and pack no more than 6,000 cartons per hour, the new lines have capacities for 7,000 cartons with 1,500 more in reserve.

This rise results in part from an increase in the speed of the lines by more than 20%, said Hals. “These new filling and packing lines let this dairy plant achieve enormous savings in production time—about seven hours daily with just the same output. That’s a factor worth its weight in gold when producing five days a week.” The potential is enormous if you consider just the quantity of milk processed by the Norwegian dairy cooperative each year: 1.8 billion liters of cow’s milk and 20 million liters of goat’s milk.

A view from afar
Built into these packing lines is a whole series of components that Rexroth developed especially for use in the food processing industry. These include pneumatic valve terminal systems with integrated DeviceNet bus protocols, rugged twin-action guide cylinders from the GPC series, corrosion-resistant pneumatic cylinders from the ISO Clean Line series, and maintenance units to prepare compressed air for use.

The configuration selected to drive the AMC lines includes an intelligent combination of ball-screw drives and ball-mounted rail guides with MSK servomotors featuring quick acceleration characteristics. These are augmented with IndraDrive C servo amplifiers. The modular concept offers a further advantage: The servo amplifier with its integrated controller can be linked directly to the dairy plant’s DeviceNet—and in this way can also be accessed from a remote point.

Clean and lightweight
A further Rexroth development intended for use in sensitive settings like the food industry was appealing to Hals: the Clean Line concept.

“Although our machinery makes no direct contact with milk, it does have to comply with stringent requirements. That means withstanding countless cleaning cycles,” he said.

That is why consistent use of stainless steel and components meeting hygienic requirements is important. Even cleaning with a jet of steam at 100°C will not affect the equipment.

The Clean Line concept joins uncomplicated care, simple cleaning and ease of maintenance with mature technology. For example, the compact, modular CL03 valve terminal system, which features an IP69K protection rating, cuts costs.

“A decentralized valve operating system eliminates long feed lines with their typical pressure losses; neither do we have to install any expensive control cabinets,” said Hals. “All that, of course, speeds assembly of the packing lines on site and makes maintenance faster, easier and thus more economical.”

AMC uses two such valve terminal systems for each packing line, populates them with 16 valves each and connects their integrated bus with the DeviceNet protocol directly to the dairy plant’s bus system. The solenoid valves in the valve terminal system are used to control the built-in GPC and ICL cylinders. The PPC stainless steel guide unit is resistant to transverse and torsional forces. Cleaning and maintaining the cylinders are made simple, thanks to a practical sensor attachment concept and the Clean Line design, aligned specifically with hygiene needs.

In his office on the shores of Lake Eiker, Hals is already planning future projects. As though just in passing he calls up, via the Internet, a user’s control panel in his own display. In just an instant he can determine whether recently installed packing lines—500 km away—are working properly.

The challenge: Develop quick filling and packing lines to keep up with the demand for the freshest milk in dairy plants.

Bosch Rexroth solution:
• CL03 Clean Line IP69K pneumatic valve terminal systems with integrated DeviceNet bus protocol
• GPC series rugged twin-action guide cylinders
• ISO Clean Line series corrosion-resistant pneumatic cylinders
• MSK servo motors IndraDrive C servo amplifiers with integrated controller
• Ball screws and ball rails

Benefits:
• Increase line speeds by 20% with capacity of 7,000 cartons per hour
• Saved seven hours per day in production time with the same output
• Clean Line valves withstand stringent cleaning with boiling hot water
• Decentralized valve terminal system eliminates long feed lines, pressure losses, expensive control cabinets
• Remote system monitoring for better maintenance