machinery | Maintenance
corrosion resistance, so it is important to maintain the water quality per the extruder manufacturer’s recom- mendation,” he says. One common issue is water pH levels that are too
low (indicating high acidity). This causes excessive rust formation and over time fouls the recirculation system and causes solenoid valves to fail prematurely. At the other end of the spectrum, water with high levels of minerals will create deposits inside the barrel cooling ports as the water is flashed off. “Regularly changing the water in the reservoir and ensuring that the water is per the OEM’s recommendation will significantly lower both phenomena,” says Bessinger. Dirk Zimmermann, General Manager at Extruder
Above: Leistritz is using “smart” technologies such as these glasses that can present critical data and instruc- tions to the engineer at the machine
begun to introduce “smart” glasses for use by person- nel at the machine. These incorporate a camera and a display that show the wearer all the instruction steps directly at the workplace. “Knowledge is shared cross-site in real time,” says Sauer. “The advantage that those glasses bring is not only in terms of time, because the service can be conducted directly from the office, but also in terms of cost savings. Machine downtimes are reduced and the customer saves money for cost intensive service calls on-site.” Sauer also highlights the growing use of sensors
built into extrusion equipment. Sensors are of course already being used to monitor melt quality, with the control unit autonomously adapting values in line with the specification. “We are currently working on launching a useful vibration monitoring for motors and gears,” he says. “In this context, it can then be com- bined with an oil level monitoring.” Vibration monitoring is already included in ICMA San
Right: ICMA San Giorgio’s latest com- pounding
machines can be fitted with the company’s I-Smart
sensor-based maintenance planning solution
18
Giorgio’s recently launched “I-Smart” solution, which involves application of sensors with diagnostic capabili- ties to the extruder. These monitor various parameters in order to detect possible malfunctions in advance, enabling customers to plan preventive maintenance activities. “This solution also makes it possible to monitor specific process parameters closely related to product quality,” says ICMA San Giorgio Managing Director Giorgio Colombo. The data collected can be made available through special apps on mobile devices or through specifically designed web portals.
Think about your water “Keep your water clean” is one of several tips offered by Janik Bessinger, Engineering Manager at CPM Century Extrusion. “Most extruder barrels are manufac- tured from carbon steel that does not have high
COMPOUNDING WORLD | April 2017
www.compoundingworld.com
Experts, also has advice to share on the importance of maintaining temperature control systems in twin-screw extruders. He says that the internal cooling system in the barrels provides one of the biggest potential sources of problems in controlling process tempera- ture. “Since most of the systems inject small amounts of water into the barrels, the water turns to vapour in a very short time, which takes out a lot of energy from the barrel surface,” Zimmermann says. “The problem in this phase conversion is that
minerals in the injected water will stay on the surface of the cooling channels in the barrels. These very small layers will add up over time and at a certain point clog the cooling system.” This effect can be reduced with water containing low levels of minerals but the problem coming along with demineralised water is the chemical affinity towards the barrel metal, which leads to corrosion in the barrels, Zimmermann notes. This means that anti-oxidising agents have to be added. “The general problem is that the user cannot inspect
this effect, whether there is mineral clogging, corrosion or other effects that reduce dramatically the flow rate of water or steam in the barrel. The cooling systems are normally permanently closed by welding or other methods,” he explains. Zimmermann says overcoming this problem was a
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