Up and Running articles
Up and Running articles
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Field Report - Yankee rebuild improves tissue quality, a case study
Rebuilding a Yankee is a daunting decision, due to OSHA regulations for confined space entry and the significant cost of downtime. This mill was losing product due to poor tissue quality, and Valmet's service engineers assisted in the decision making process to rebuild the Yankee.
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Field Report - Roll grinding procedures
Successful roll grinding depends on many factors. The knowledge and experience of an operator, the condition of the roll grinding equipment, and continued preventive maintenance of equipment, all contribute to the ability to meet dimensional tolerances and surface finish requirements.
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Field Report - On-machine grinding increases machine speed and sheet quality, a case study
At a fine paper mill, despite every effort, sheet breaks had averaged more than six a day for the last several months. Two of the four dryers were shut down and the two functioning dryers would need to be taken off-line soon if nothing could be done...
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Field Report - On-machine grinding
On-machine grinding is cost- and time-efficient compared to dryer cylinder replacement or off-machine grinding, finishing and renewing cylinders for 40-50 percent less total cost and in less than half the time.
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Field Report - Headbox apron shower troubleshooting, a case study
The key word in papermaking is uniformity, and the apron shower plays a primary role in maintaining this characteristic. Shower water volume, pressure and temperature are critical factors. The case study involves the three indicators of a thermal bow problem in the apron lip.
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Field Report - Apron lip mapping and repair preparation
Apron lip damage usually comes in the form of nicks, scratches or dents. These minor abrasions can trap fibers from the pulp or cause distortions in the flow of the headbox jet, which jeopardizes sheet formation. Preparation before apron repairs can improve maintenance safety and save money.
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Field Report - Winder preventive maintenance
Sheet breaks at the winder can bring the entire papermaking process to a stop. To prevent this, the winder needs constant attention through a sound preventive maintenance program (PMP).
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Field Report - Differential drive maintenance
The differential drive supplies power to the individual machine sections, and maintains a constant preset speed between those sections. The slightest speed difference between sections can result in a sheet break and lost production. Knowing the drive components and what to look for helps in preventive maintenance.
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Field Report - Chronic dryer drive oscillation, a case study
The clack-clack-clack noise warned of heavy oscillation in the drive, subjecting the machine to potentially damaging duress. The only known cure was a shutdown and restart, costing the mill productivity and dollars. The shift supervisor calls in a drive technician for assistance...
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Field Report - Cleaning VacRolls
VacRoll suction holes and the grooves of all rolls should be cleaned regularly, as they may get completely clogged due to web moisture, particularly at the start of the dryer section. Bearing housings also need attention. Proper handling of the rolls is also important.