Execution of the project
When BERALMAR was called to study the case, their experience in large-format manufacturing using other types of dryers was key to understanding the root of the problem.
These sub-roof bricks at BELIANES CERAMICS PLANT are manufactured using a double-bar extrusion system, and the extrusion is always different on each bar. Contrary to the general perception, the pressures and tensions in different parts of the bar always differ, even though in most cases these differences are not obvious, as with all other brick formats at CERÀMICA BELIANES.
The fact that most of breakages took place in handling between the dryer and the kiln made BERALMAR technicians suspect that the extrusion was the source of the problem. The small differences between each bar surfaced as various torsions in large pieces during drying, a phenomenon which was imperceptible in smaller formats. Due to their considerable size, these pieces are very sensitive to handling when dry, especially at the setting.
Once the problem was understood, the solution proposed by BERALMAR could not be simpler. The solution consisted in respecting the extrusion bar origin at the kiln car setting. In other words, each packet from the kiln must include only pieces cut from the same bar. Thus, each piece in a given kiln car packet boasted the same type of torsion during drying, thereby eliminating the stresses produced by setting materials with different torsions.
Thanks to the application of this simple solution, large format production wastage dropped from 25% to well below 10%, so that the plant was able to definitively approve the production of this material.
This case study reinforces the idea of multi-product factories featuring a direct setting dryer. In addition to the known advantages (lower thermal consumption, less investment, easy management, etc.), there is no other more effective dryer when it comes to drying large formats. The fact of setting pieces on top of each other guarantees drying without torsion, while the absence of handling between the dryer and the kiln avoids mechanical breakage in such long and delicate products.
Implicitly, this case is also an example of the experience in solving problems by the BERALMAR kiln and dryer regulation technicians. And not all problems require big solutions. Often an appropriate adjustment or simple actions can solve big problems.
The next case study will be published in Newsletter #128, July 2018.