MACHINERY | SCREWS AND BARRELS
Right: Glycon’s detection sensors are inserted into ports on the side of the barrel, to measure screw and barrel wear
bore gauges,” he said. “EMT requires one hour per line, once or twice a year – which gives the proces- sor has all the information they need to make a sound economic decision.” The system relies on a Glycon product called
Smartbarrel, which has several apertures along its length called Smartports. A barrel wear plug is installed in the aperture and seals the port. This is done during manufacturing – at the final honing operation – so that it matches the surface and inside diameter of the barrel. To take a measurement, the plug is removed
from the port and replaced with a threaded retainer – which secures an eddy current sensor in place. With the barrel and screw at or near operating
cally in ceramic and chrome seal coatings for demanding applications.
“By working closely with customers, we continue to develop solutions to meet the most demanding process applications,” he said. Magog has also designed screws and barrels that can cope with the extra demands of regrind material – which has become more prevalent recently.
Dual measurement US-based Glycon has developed a system that monitors wear on both the screw and barrel. The company says it has used its EMT system – which stands for Electronic Measurement and Tracking – for some time but has never before made it commercially available. The system uses an eddy current sensor combined with a barrel wear plug to gather accurate data on both screw and barrel wear. It is the subject of a 2019 patent. “With the data derived from these measure-
ments, processors can predict the rate of wear, and the best time to replace or repair the screw or barrel,” said Jeff Kuhman, president of Glycon. “This process has been commonly referred to in recent years as predictive analytics.” Kuhman says the system can be used in both pipe and profile extrusion, as well as for film and sheet. EMT has been field tested at a number of Beta sites and offers simplicity, accuracy and reliability, he says. “Many processors still run to failure because it is time-consuming and costly to take a line out of pro- duction, dismantle the screw and barrel and physically measure the parts with micrometers and
24 PIPE & PROFILE EXTRUSION | March 2021
temperatures, the screw is rotated slowly. The sensor generates an accurate reading that is averaged over many rotations to allow for ‘precession’ or ‘orbital’ rotation of the screw inside the barrel. “We have refined and improved sensor accuracy over the years to a point where the reading is accurate to .001 or better,” said Kuhman. The barrel wear plug is then installed in a
measuring fixture that has openings at both ends. The sensor is installed at the opposite end. Any deviation from the original measurement constitutes barrel wear, says Kuhman. The system can track total wear per million lbs of material processed – from which the wear rate can be calculated. “By comparing the wear rate to the amount per
hour produced, you can determine the rate of wear, cost of wear and from that determine the best time to replace the screw and barrel,” he said. The customer can analyse the data indepen- dently and will typically use it to boost productivity, lower scrap rates and cut energy costs, says Kuhman. He adds that Glycon can also help to interpret results and make recommendations on materials of construction, screw design and screw barrel alignment that could extend the lifetime of the new barrel and screw. Glycon has tested the EMT in its lab for a number of years, in conjunction with partners such as sensor manufacturers, instrument manufacturers (both eddy current and ultrasound) and processors. “We have to make the process failsafe as the
tools are expensive and fragile,” he said. “The bigger the machine, the more cumbersome and time-consuming it is to tear the line down to manually check the screw and barrel for wear. EMT will take less than an hour, while heats are main- tained and the screw is turning.” Kuhman expects to roll out the first stage of EMT in the second half of this year, by offering Smart- barrels for sale.
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