Alignment – strong maintenance tool.

The Hot kiln alignment inspection service is generally performed by specialized company. This is recommended to carry out this kind of service every two years, in case when kiln cannot be stopped or in case of important and dangerous failures like cracks (on tires or rollers), brick failure, hot bearing problem, base frame cracks, shaft crack etc.

The question is why the alignment is so important and everybody pay special attention to it?

Firstly – rotary kiln is very heavy. It reaches hundreds of tons.

Secondly – this kind of machines and each component is very expensive. For example one tire 60 tons weight can cost 200.000 USD, one roller (about 45 tons weight) cost is 120.000 USD.

And finally – all rotary kilns are designed with minimum safety factor. Almost all suppliers design it at 95% of the limit, so the margin is very limited. The limitations can appear everywhere: maximum stress in the tire or shell, maximum pressure of tires and rollers (contact surface), maximum pressure between liner and shaft etc.

To illustrate the consequences let’s compare perfectly align kiln unit and one with misalignment.

Three-pier kiln well aligned characterizes no crankshaft, no misalignment of support, all tire working perfectly on rollers (within design limits). All values are within tolerance and rotary kiln can work without unexpected stoppages and additional costs.

For poorly aligned kiln situation is a lot worst. Let’s assume the same three-pier kiln but poorly aligned. Tire at middle station is 10mm too high. Because of stiffness of the kiln (that can be calculated from stiffness matrix) the second station is overloaded. This overload create many problems like tire and rollers mechanical wear, cracks, holes and many others. The bearing liner damage will appears as well. All this problems lead to kiln unit stoppage, renovation work, parts replacement and most of all additional and very high costs.

Generally most of that kind of situation can be avoided by regular kiln alignment service.

Rotary kilns should be inspected in cold condition every twelve months during kiln stoppage, at each support roller or other important part replacement or every time when some problems will appear.