The procedure:

1. measuring sensors on
   both sides of the Yankee
    
2. trigger delivering signal
   for angle / rotation

The main problem with Yankee dynamic balancing is the low frequency at which the Yankee is rotating (around 1.2 – 1.3 Hz).
It´s difficult to get vibration analyzers and sensors, which do operate properly with reliable data outputs at these low frequencies.
The picture on the right shows a data sheet of a typical acceleration sensor.
Please note that in a frequency range of around 10 – 1000 Hz the response is flat.

One year ago, Jaeger GmbH balanced an Andritzdryer in Germany, the manufacturer´s vibration specialist measured as well balanced (below G 1.0).
Unfortunately the customer continued to have serious vibration problems.
JAEGER has developed special equipment to operate, and to be able to analyze responses in low frequency ranges.
During our dynamic balancing we had to add 40 kg or 80 lbs balancing weight to reach values around G 2.5!

Advantages of dynamic balancing:

• lifetime of the bearings extended to up to 20 years
• lifetime of the press covers and bearings extended (less barring)
• significantly less vibration on doctor systems and presses (less surface chatter)
• increased doctor blade life
• more stable organic coating
• extended operating window, especially at higher speed
• Recommended balancing service intervals: 10 Years

A calculation example ...

Yankee	SI Units	Imperial
diameter	4.572 mm	15 ft
face length	3.300 mm	130 "
operating speed	1.800 m/min	5.900 SFPM
Prior to Balancing
unbalance (typical)	50 kg	100 Lbs
creating centrifugal force	14 KN	2.800 lbf
After Balancing
rest unbalance (typical)	3 kg	6 Lbs
creating rest force	0,85 KN	70 lbf

 

 

 

 

 

 

Before and after balancing: dynamic forces transmitted to the bearings and frame;
frame movement and frame absorbed energy is reduced by a factor > 10.