In the age of email, it might be assumed that the paper industry would be in decline. Not so; thanks in part to one of the other pillars of internet activity—online shopping—the packaging industry has seen a huge boost in the card used by retailers such as Amazon.

In Germany, the paper industry sold around 23m tonnes of paper, cardboard and paperboard in 2017—an increase of 1.4% on the 2016 total. Sales in the packaging sector increased by 3.4% last year.

Increased sales means more product being shipped, and therefore more demand on the logistics chains that move rolls of paper from manufacturer’s warehouse to truck to customer.

Talking to Demag’s sales director for process cranes, Markus Otto, at Logimat in Stuttgart earlier this year, we discussed the use of the company’s warehouse management system, or WMS, in the paper industry. The software can calculate the optimum positioning of paper rolls in a warehouse to minimise the time it will take to load forthcoming orders, as well as operating a crane with two trolleys working independently to maximise throughput.

“A paper manufacturer knows how to make paper, and the market, but will not be an expert in logistics,” says Otto, which is where Demag come in. The company offers virtual planning as a first step, simulating different approaches to ascertain which is the best solution.

This is based on information provided by the customer, such as load dimensions and weights, their product portfolio, how much storage capacity they have and the required throughput. The simulation tool then calculates, based on those parameters, the best way to set up the warehouse and the number of cranes, with the aims of enabling the paper rolls to be stacked and unloaded efficiently, providing access to the right products for upcoming orders, and minimising waiting times for trucks to be filled, often in multiple loading bays. The cranes controlled by the WMS can also work overnight to make sure the correct rolls are accessible for the orders being loaded the next day.

“Several years ago, storage capacities were growing, but the industry couldn’t see how increasing the number of cranes would help logistics,” says Otto. This new approach—featuring automated handling and positioning with up to seven cranes, occasionally also containing two attachments moving independently on one crane—addresses this.

To make sure that the customer gets what fits for purpose a simulation of potential designs of a facility makes a lot of sense before it is built. The simulation includes conveyors, says Otto, enabling it to create complete logistical solutions.

There have been two installations with two independently moving attachments in the paper industry so far, both in Europe, says Otto—and the scope of the WMS will allow it to be used in a wide variety of industries beyond paper.

“Our automatic crane solutions including WMS are all designed in house and are suitable for paper, automotive, metal coil and sheet, wooden products, straw bales; any industries with fairly high volumes,” says Otto. “The cranes we supply to each sector are specialised in terms of the typical speeds, capacities and lifting attachments required by that industry.”

There is more and more automation in the handling and logistics industry, says Otto, partly due to increased product variety and greater storage space requirements—for example in the automotive industry where dies for different vehicle models may be stacked vertically, and changeovers need to be done quickly and efficiently, with the next required die therefore needing to be available straight away to be moved into the press. Fully automated processes are increasingly common—although the WMS can also be used to guide the manual operation of cranes, for customers who prefer it.

Of course, operating two or more trolleys on the same bridge requires sophisticated computing. Power Electronics International (PE) recently supplied the electronics for a crane with three trolleys on one bridge, for use at the Kruger Paper Products facility in Memphis, Tennessee.

When crane A and C are selected by the operator, hoists A and C are operated in tandem, with all three trolleys, A, B and C, moving together.

PE, which has been manufacturing electronics for hoists and cranes for 50 years, supplied a seven-motion roll crane control system incorporating the PE Multi- Vector variable frequency hoist drive, which performs all the speed control, as well as other programmable functions.

The Multi-Vector system also monitors torque readings from the motors to calculate the loads on the three trolleys, which is sent to the PLC for analysis so overloads can be detected, preventing the operator from lifting a combined total weight on the three trolleys that is above the safe working load of the crane.

The drives supplied by PE are rated to 60C, compared to the 40C rating of the most VFDs, said the manufacturer, which is an important advantage in the environment of a paper mill. The company also included stainless steel regeneration resistors due to the long, heavy-duty lifting times, which are greater than two minutes at high load.

Increasing throughput and efficiency through automation becomes more important when demand is as strong as ever. “We have seen a continued demand from the paper and card industry,” says Jim Kluck, global product manager controls and automation at Magnetek, a Columbus McKinnon company. “Even as companies have moved away from producing traditional print materials, we have seen a growth in corrugated stock and container board production. Paper recycling as a segment of waste management has also been an area of increasing demand.

“Automation is all about combining the right technology to deliver safe and productive operation. Next generation technology such as no-fly zone systems, HMI screens, and wireless communication simplifies maintenance, enables easy troubleshooting, and improves operation. Accurate, repeatable processes provide enhanced process flow, reduced idle time, consistent operation, and improved cycle times for increased productivity. Overall, the user-defined, programmed machinery movement paired with advanced system monitoring, analytics, and diagnostics improves the safety, productivity, and uptime of a facility.”

Another key advantage of automation and digitalisation is safety, says Kluck: “Managing a safe lift is a priority for paper and card applications. Large overhead cranes managing the heavy loads of items such as paper rolls and corrugated boards must operate with precise movement and placement or risk the safety of operators and system equipment.

“Through years of working with paper handling applications, Magnetek has developed key software functionality like Collision Avoidance, Safe Lifting, Load Check II and more that allows the operator to safely lift a load while maximizing productivity.

“Depending on the application, no-fly zone systems can incorporate a variety of motion control products, including variable frequency drives, radio remote controls, limit switches, and sensors to designate locations where a crane is programmed to stop.

“Implementing no-fly zones limits the risk of collisions, increases safety for equipment and personnel, and improves facility throughput. Configurable no-fly zone systems utilise laser positioning sensors installed on bridge/trolley motions that interface with controllers for functional customization. The system incorporates a simplified menu-driven operator interface accessed over a 2.4 or 5 GHz wireless connection via the use of a Personal Electronic Device (PED) such as a laptop, smartphone, or tablet. This operator interface provides flexibility to configure no-fly zones and enable or disable as changing process, plant, and crane conditions require.”

Another part of ensuring throughput remains optimised in facilities such as paper warehouses is preventing crane breakdowns, which can cause lengthy downtime. Demag’s parent company Konecranes offers an Oil Analysis service, a means of predictive maintenance involving analysing the degradation of the hoisting gear oil in addition to their Crane Reliability Service (CRS).

The company conducted such a survey at the Palm paper factory in Wörth am Rhein, Germany, a manufacturing facility with an annual capacity of around 650,000t of packaging raw material, with surface weights of up to 160g/m2, and where 11 double-girder cranes are used day and night to transport the paper rolls. Konecranes analysed the gear oil of eight of the most critical cranes and used an endoscope to look at the gears, as well as the wear metals and waste substances.

The cranes have been in operation since 2002 as part of paper machine 6 (PM6), one of nine paper machines across five factories operated by Palm. “The cranes are in use day and night,” says Sven Bohrer, electrical engineer at the Palm paper factory. “If one should break one day, the production would have to stop, or at least greatly slow down, until the problem is solved. This would cost us time and money.”

Nico Zamzow, vice president industrial service EMEA central at Konecranes, says: “The oil analysis protects the crane. Any damage or wear can be identified and treated early with its help. Moreover, system operators are able to optimise the maintenance and servicing of the cranes thanks to the detailed analysis report, and thus significantly increase their lifespan.

“The samples are analysed by our laboratory, which specialises in industrial drive train analysis. Here, the lab staff compares the current state of the oil with the samples taken in 2016 and against the OEM design limits. This way, we also use trend analysis to provide the best possible picture of any change within the condition of the gearbox.”

At Palm, seven of the eight cranes analysed were found to be in good condition, with the gear oil containing few or no foreign elements or waste substances that indicidated contamination or wear. The automated number 5 crane used in the roll warehouse, however, had a notable increase in its wear particle count, which was highlighted by the laboratory. “Iron particles in the oil can be an indication of increased wear and a deeper look may be required for this particular hoist,” says Zamzow.

The next stage was to identify the issue causing the wear, before permanent damage was caused. “If the gear is jammed while there is a roll on the hook, it becomes very difficult to recover it and repair the crane,” he explains.

Konecranes used its Crane Reliability Study (CRS) to see if damage has already been done, using modular analysis to check safety-relevant components such as the hoisting gear, steel structure, motors, and electrical equipment.

The company’s maintenance experts gather more information by discussing the issues with crane operators and technicians. And an oil-resistant, highdefinition video endoscope is used to examine the areas of concern. After the analysis and inspection was completed, Konecranes concluded that the hoisting gear in the crane needed to be replaced, along with renewal of the cable drum, cable drum support, slip-ring unit, cylinder coupling, and motor coupling. “Thanks to discovering the wear early on, there was no risk to safety and we were able to replace the old gear with a new one without affecting production,” says Zamzow.

Lee Thorne, director of service sales, Industrial Service EMEA at Konecranes, explains the service in more detail. “The service provides a deep insight into the condition of gearboxes, for cranes in the paper industry, or in similar sectors where production cranes are critical to operations. For those sectors the real cost of a faulty gearbox isn’t the repair, it’s lost time.

“It involves minimal or no disruption—if maintenance is already taking place, it takes no time to take an oil sample, which is then analysed off-site.

“We service and maintain all makes and models of crane, and take thousands of samples. Of those, in around 20–25% there is something of note that needs to be monitored. Operators need to know when to change the oil, as it loses its usefulness over time and mechanical components can be damaged if the oil is used for too long. Certain particles in the oil, such as copper and iron, flag up potential issues, and gives the customer a bigger notice period in which to respond.”

Oil from the hoist gearbox is the key sample to take, says Thorne, although oil from the lateral travel gearbox can also be tested. The process is part of a larger maintenance offering from Konecranes that includes the Truconnect system, which allows crane performance to be monitored in real-time, along with collating data from other systems such as brake monitoring units.