Saving energy in clay brick production by use of vibrating cutting wires

In the industrial manufacture of insulative, vertically perforated clay bricks designed to help ultimate consumers save energy in their own homes, there are numerous steps of production to be accounted for, if the end product is to display the requisite qualities. Each and every step of manufacture consumes energy, so even minor increments of optimization can add up to major savings.

If vertically perforated clay bricks are to display the desired insulative properties, their bodies must be appropriately porous. This is usually achieved by adding combustible, void-forming additives derived from waste material from the papermaking, wood processing and packaging sectors. As the insulation requirements to be met by bricks become increasingly stringent, more and more porosification agents – in the form of papermaking sludge, sawdust or shredded polystyrene from old packaging material – have to be added to the clay. However, the fibrous structure of such additives can cause the cut face of the brick to deform. This problem can be minimized by adopting appropriate cutting technology. Otherwise, the fibres can cause the cut face to “smear” so badly, that some of the core holes are closed off. That, in turn, impedes both the flow of drying air through the hole and the expulsion of water vapour from the hole during the subsequent drying process.

Both defect sources can be reduced or even prevented, depending on the material characteristics. In most cases, this can even be achieved with less force applied to the cutting wire.

In the case of unporosified facing bricks, the problem is less to prevent deformation of the green bricks than to enable good cutting despite reduced batching water and with no change in applied force – or with the same amount of gauging water and less force applied to the cutting wire.

Trials performed in the course of an IZF research project yielded consistently positive results for the use of a vibrating cutting wire. Braided cutting wires, with their elevated inherent elasticity, were successfully employed as a means of preventing wire breakage cause by operation at resonant frequency. The experiments revealed that, for each increase in cutting speed, the frequency of vibration must be altered accordingly in order to preserve the positive “saw effect”.

To enable application of high-frequency vibrations, the wire should be moved by a piezoelectric drive mechanism of the kind commonly found in today‘s high-precision mechanical engineering applications.

Eckhard Rimpel, Brick and Tile Research Institute Regd, Essen, Germany

Related articles:

Issue 2012-11

Frost resistance of high-porosity vertically ­perforated bricks

On European level, efforts are being made in the scope of work on international standards to define uniform requirements for the frost resistance of vertically perforated bricks. In the production of...

more
Issue 2012-10

Reducing energy expenditures for brick production by use of vibrating cutters

1 Background and problem description Large-format, porosity-enhanced, vertically perforated clay bricks with high core-hole fractions and filigreed webs call for the use of materials with good...

more
Issue 2017-6

Improving the quality of cut and reducing energy expenditures for brick production by use of vibrating cutters with piezoelectric and electroosmotic drives

1 Background The vibration cutting technique employing an oscillating solenoid, as already investigated in project AiF 16074 N, enables achievement of a cleaner quality of cut coupled in most cases...

more
Issue 2019-6

Building component testing – measurement methods, results, practical relevance

For building approvals for high-precision vertically perforated bricks, structural strength tests on individual bricks and specimen walls are essential. For high-precision vertically perforated bricks...

more
Issue 2019-6

Measurement and numerical analyses of the acoustic behaviour of vertically perforated bricks

At the Brick and Tile Research Institute in Essen, a numerical and two-dimensional simulation model was developed on the basis of the DIN EN ISO 10140 series of standards. The objective was to...

more