Rapid Rebuild at APP
Record broken in just eight days
2013-11-08 - The paper manufacturer APP wanted its BM 6 board machine to process 1,100 m/min – more than a machine for high-quality art board has ever produced. To achieve this goal, suction forming boards and a suction roll were installed, the press section was supplemented by new water doctors, and splash pans and the entire dryer section was reconfigured. Everything was to take eight days and not an hour longer. It really couldn’t be done – really.
Ultimately, the rebuild of the dryer group had the aim of making additional drying capacity available and in the process leaving the length of the dryer section unchanged. “This was the most elaborate part by far of the entire project,” says project manager Robin Liang. “We had to drill cylinders, dismantle rolls that we no longer needed and finally remove doctors so as to have enough space.” Space was needed to mount new DuoStabilizers on cylinders 5 and 7. The aim was to make a supported paper draw out of an unsupported one and thus to noticeably increase the speed through fewer web breaks.
A second measure on the dryer group also served this purpose: Voith attached a drilling rig successively on cylinders 5 and 7 that drilled several thousand holes to make a Supported web run possible in the future. In the process, the cylinder turns cyclically under the drilling rig, always one unit further. This process alone took two and a half days for both cylinders – two and a half out of eight.
Like clockwork. Not one hour can be wasted; the team has to work together like the geared wheels in a clock. Robin Liang: “In a rebuild such as this, 15 or more people are operating in the tightest space under time pressure, so the coordination has to be 100%. I imagine the building of the pyramids in ancient Egypt as being similar; there, too, a few coordinated, and many pulled on innumerable cords and hoists in order to move the gigantic stones.”