PURPOSE
Purpose of this Guide is to provide information and knowledge required for performing product change from 1312RE to 1312FR without stopping board-line in aim to improve machine efficiency, increase product output and improve profitability of the business.
SCOPE
Board-line downtime for this particular type of product change is approximately 15 minutes. This change is performed at least once a week (usually some 24 hours before weekly maintenance. Approximately fifty of these changes are performed during a year equaling 750 minutes. That equals 36,000 square meters of most commonly produced product in our plant at current board-line speed (1012RE). It is needless to say that dryer would be better utilized by 750 minutes (due to rapid temperature loss we do not shut drier down as it would be counterproductive in terms of energy consumption)
Every shut down and start up are associated with inevitable product loss – this varies but an average loss for this product change would be around 150 square meters.
Change from 1312RE to 1312FR is not particularly demanding at forming station (we don’t have to change product width nor edge thickness. Core mix changes are more significant but not outside crew’s abilities to handle them.
Previous trials have been performed without taking into account drying process. Feedback from our customers is pointing to problems associated with this change that is pointing to drying process – paper de-lamination and “soft edge”.
DEFINITIONS
Gap in the dryer – Gap between boards going through the dryer created by rejecting boards on the Wet End Transfer for whatever reason (faulty product, splice, change of the length…)
Drying Process – The process of removing water (moisture) from plasterboard. In this process air stream applies the heat to the board causing evaporation and carries away the vapor.
Drying Time – The time board spends travelling through dryer. Drying time is different for every product manufactured in our plant. Drying time directly depends on the dryer chain speed, which depends on the board line speed.
Drying Temperature – Temperature set points for dryer zone 1 and zone 2. We have only two zones dryer in Matraville plant. Drying temperature is not constant throughout the length of the dryer. It depends on temperature set point, position of board in the dryer, level of heath exchange etc.
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