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S. Bederian Technical Service LLC offers the services of an acknowledged paper-making machine tail-threading process expert.  The paper producer may turn to S. Bederian Technical Service LLC for analysis of threading difficulties or service and optimization of existing threading equipment. FibronTM vacuum tail threaders are a specialty.

Under ideal situations a paper machine can produce a web of paper at high speed 24 hours a day for extended periods between wash-ups or shutdowns.  Sheet breaks do occur, making it necessary to thread the sheet through the machine.  Reducing the time necessary to re-thread the machine or allowing the machine to more quickly return “on-grade” can directly impact the overall machine efficiency.

 

Threading of a paper machine is done by cutting a narrow tail from the running web.  It is this tail that is passed through the machine a section at a time. Once the narrow tail is though a section it is opened out to full width and the process is repeated for the next section.

 

History: In years past it was common for this process to be done completely by hand, operators would climb the paper machine and pass the paper-tail one to another around the various rotating equipment.  Photos from the late 1800’s usually show the machine and the whole crew. Close inspection would find several operators as barefoot (making for safer climbing on a slippery machine) or with missing digits.

 

Rope threading was introduced to eliminate the need for climbing the machine as production speeds increased.  Multiple tail-carrying ropes (usually 2 but sometimes 3) are passed through the machine. The tail is captured between the ropes and carried through a section. The rope system is mechanically complex and its effective adjustment and maintenance can directly affect the machine efficiency. Section to sections transfers were still done by hand requiring a skilled operator with precision eye-hand co-ordination as rope systems have their own unique safety concerns. Modern machine speeds have increased to the point to make a hand-pass transfer into a rope-nip a safety issue to note.

 

Air-trays were introduced to mechanically transfer the tail from section to section or to offer rope-less section threading. When used within a narrow window of operation, air-trays can be quite effective. Many machinery suppliers produced flat-tray type devices such as Mount Hope among others, tubular air-trays were a feature of Beloit light-weight machines. Air-tray systems can be challenged by large changes in machine speed, sheet weight or moisture.

 

Threading conveyors for mechanical tail transfer appeared in the mid-70’s produced by Durand Machine of British Columbia, Canada.  This device uses vacuum to attach the tail to a conveyor and can transport the tail more effectively at the highest machine speeds and over a wider range of sheet weights.  These machines often require sophisticated control. This style equipment is in use from various sources: Fibron, FoilForce and  SurePassTM amoung others.

Most machines in production today incorporate some or all of the above threading styles.

 

Control of threading equipment can range from simple hand valves and hard-wired pushbuttons to complex semi-robotic operation via digital machine process control.  It takes an experienced hand to assist in the troubleshooting and modification of controls.

 

Fibron is a registered trademark of Voith Paper Corp.

FoilForce is a registered trademark of Metso Paper Corp.
SurePass is a registered trademark of Paperchine LLC.

 

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