When the support rollers are not in a correct geometrical position the rotating load is different for each pear, each roller. This condition has strong influence over kiln service life. Misalignment causes the same overloading stress condition like crank in the shell. The difference is that the bend of shell creates overload stress once per revolution of kiln, not correct position of kiln axis has a negative impact on a permanent basis. This geometrical situation can lead to many serious damages like cracks, refractory lining failure, hot bearings, under-tire shims cracks, rollers shaft damage, high amperage during operation. Deformation of kiln shell? always when the kiln shell is misaligned precise alignment measurement should be performed.
The kiln shell misalignment is very difficult o detect visually in contrast to cracks or heat damage. Precise measurement are necessary. The first sign, symptom of axis deviation often can be a rise in amperage usage during operation. As even small deviation can lead to big damages alignment measurement and data obtained has to be very precise and reliable. This kind of work is generally carried out by outside companies, sometimes by Cement Plant crew.
When the user identify the shell geometry problem it is very important to define the scale of impact of deviation. A shell profile measurement can be very useful in this case (shell profile is a measurement of radial run-out of each segment in relation to rotation kiln axis). Measurement can include all length of machinery or only the part where some damage is visible. The data we can get from complete shell profile is: eccentricity of segments, flat parts, blisters, crank formation appearance and many others. Knowing the real shape of shell and compare this with different measured parameters we can assess the changing in load distribution and precisely locate the reason of potential or existing problems. This data can also be used as a base of choice of best method of repair or parts replacement. If it is necessary to change same segments the shell profile measurement give you the precise information which one.
The basis of the Preventive Maintenance is to find the causes of potential problems long before it will going to appear. Experienced diagnostician will reduce the future kiln failure based even on the smallest symptoms and abnormalities of kiln operation.
The most important case of misalignment is that even one small deviation of one parameter can lead to further damages (of other parameters). It is called a Chain of Causes. That is why the alignment measurement and adjustment service is so important. It should be the base of preventive maintenance strategy. Even if kiln operation looks good it is worth to control and monitor this condition and reduce irregularities on the beginning. The investment in the alignment measurement returns after first unplanned stoppage.
Summary we can say: when the problems are visually obvious It is too late.