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NEW LISSMAC SAW AND MATERIAL FLOW CONCEPT AT THE XELLA-FACTORY IN GRIEDEL
A Revolution in the manufacture of sand-lime bricks
Sand-lime brick is growing in popularity as a building material due to its many advantages. Wall construction kits in particular, in which all the stone elements are made to fit in the factory and thus no longer require time-consuming modification on site, are experiencing strong growth.
The Lissmac saw and material flow concept revolutionises the manufacture of fitting elements made of sand-lime brick

Sand-lime brick is growing in popularity as a building material due to its many advantages. Wall construction kits in particular, in which all the stone elements are made to fit in the factory and thus no longer require time-consuming modification on site, are experiencing strong growth.

This is reason enough for the plant designer Lissmac in Bad Wurzach to continue improving its sawing, handling and feed concept for manufacturers of custom sand-lime brick elements. After state-of-the-art sand-lime brick presses were made to vary the length of the fitting pieces during running operation, the engineers at Lissmac increased the productivity of the latest generation of sand-lime brick factories by applying new materials handling technology.

The starting point for this revolution in the manufacture of large sand-lime bricks was the recognition that by using two-dimensional variable press technology

theoretically 35% of the waste volume and 60% of the sawing length could be saved. The challenge for Lissmac now was to develop a significantly more complex, new computer-supported feed and handling concept.

And as Hermann Hoegg, a technical specialist and sales manager at Lissmac found, "Our engineers mastered this challenge with flying colours."

The basis for the redesign of the material flow in sand-lime brick factories was the frequency analysis of fitting pieces with chop, vertical, gable and dynamic angle cuts or slots. The possibilities of state-of-the-art variable sand-lime brick presses, which make many saw cuts superfluous, were also fundamental considerations.
Maximum run times with automatic universal saws by Lissmac

The high-performance automatic universal saws (AUS for short) by Lissmac remain at the heart of the new generation of plants. Linked to the CAD system, they have a sawing capacity of up to 50 fitting pieces per hour. Many years of experience here result in minimal wear and maximum run times. This is important after all, because the sawing plant is always a potential weak point in the production chain due to the tremendous demands placed on it, which affects the production readiness of the entire plant.


Greater productivity with fully automatic palleting in some areas


LISSMAC sawing plant
Whereas the elimination of many cuts enables the sawing capacity of the AUS to remain constant in any modernised plant, the actual revolution is in the flow of materials. After all, about 69% of the fitting pieces, which used to require a chop cut before the use of the variable sand-lime brick press, now only need to be placed on the right pallet by an intelligent conveyor and palleting system passing by the saw. Lissmac was the first to present a solution in which large parts of the palleting process could be performed automatically using robot technology.

While palleting of the fitting elements that require no chop cut in the future takes place fully automatically now, the remaining elements are loaded semi-automatically on five different pallet stations at the same time using an intelligent colour guide system.


Of course, for material handling, in addition to high-performance handling robots, proven Lissmac technologies such as two-cable chain belts, roller chains and rugged drives with a geared motor are also used.


Intelligent control with Lissmac production software

Sophisticated Lissmac production software supplies the necessary data to the new variable sand-lime brick presses. Based on orders entered in the system, it determines the optimal sequence of press procedures with the goal of achieving lower setup times by making as few changes of the element thickness and length as possible. The algorithm used by the experts from Lissmac to solve this problem also considers the necessary optimal utilisation of the hardening cars for efficient use of the autoclave (the pressure tank for hardening sand-lime brick), as well as how to minimise saw downtime and optimise the filling of pallets at the end. Of course, the Lissmac software MV also enables each element in the production process to be located exactly, so that plant management always knows how soon an order can leave the plant. This also means that cost-optimised just-in-time production is possible with this software.


Total productivity increase of two and a half times the order volume

Altogether, the new Lissmac control software in conjunction with the optimised conveyor and handling technology and the use of a state-of-the-art, variable element length sand-lime brick press enables a 10-hour shift to produce 2.5 times the previous volume. This usually makes replacement of the saw technology unnecessary, since the required sawing per wall construction kit is significantly reduced by the more efficient concept.

"As a traditional manufacturer of saw and handling technology, we are proud to be able to set new standards in the field of plant technology for manufacturing sand-lime brick," said Hoegg. "As a general contractor, we are not only available for the complete redesign, but also for for retrofitting of manufacturing operations for fitting elements. In doing so, we place great value on continuing to use existing plant components as much as possible, which makes Lissmac a competence center for a wide range of customers in the building materials industry." This is certainly an advantage of the company not to be underestimated in the further development of the market.



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