Address:
Glafo, PG Vejdes väg 15,
SE-351 96 Växjö
SWEDEN

Visitor's address:
Vejdes plats 3

Tel: +46 10 516 63 50
E-mail: info@glafo.se

You find a map at the
"about Glafo" page.

Project leader: Christina Stålhandske
Project status: on-going project


POLISHING GLASS BY MEANS OF WATER CUTTING TECHNOLOGY – CROSS-DICIPLINARY COLLABORATION FOR SUSTAINABLE DEVELOPMENT


The aims are:
- to develop an environmentally friendly polishing technique that produces the same finish as an acid-polished finish; for flat surfaces, cut edges and holes both in float glass and in crystal glass
- to create a network within this field
- to appoint a person in the area of water cutting
- to produce a prototype glass polishing installation


You can read the first report and the background of the project here.
You can read the second report here.
You can read the third report here.


Blasting


Figure 1 At high pressure, we get a very strong blasting effect, but this is also evident at low pressure. The sample is polished using the 1 mm nozzle and Sillitin polishing agent.

We have experienced major problems with the surface that has been polished also having been blasted, see Figure 1. It is only at very low pressure that we are not able to see blasting craters in the surface.

The polishing agents and blasting sand used during the very first trial runs have been analysed. It was proven that the polishing agents also contained sand. When the entire system was very carefully cleaned, sand was found inside the pump - probably remnants from the first runs. There is also a risk that dust from the water jet cutting machine, located in the same room as the polishing equipment, contributes to the contamination of the polishing agent. Now that the reason for the blasting effect has been identified, we can eliminate it and concentrate on improving the polishing process.

Analysis of polished surfaces

Figure 2 The optical profilometer that has been purchased.

An optical profilometer, NPFlex, has been purchased and is to be installed in mid-September, see Figure 2. It makes it possible for us to measure the surface roughness and obtain high resolution 3D images of the polished surfaces. The profilometer that we finally purchased has a large work area, which means that we can measure the surface roughness of finished products such as large bowls. The lens has a long working distance which means it is possible to measure down into cuts, for example. Read more about the new equipment here.

If a surface that we have polished with Sillitin (Figure 3) is examined, it is possible still to see ridging caused by the grinding. We have not removed a sufficient amount of material to get rid of the grinding ridges but other irregularities have been reduced so the surface begins to look shiny.


Figure 3 Sample polished using the 1 mm nozzle and Sillitin, as in Figure 1. It has been analysed using an instrument similar to the one we purchased.

Strategic sustainability analysis
Work has commenced on the strategic sustainability analysis, and this is the receptacle that we are to compare with the acid polishing. The analysis being carried out is intended to show the impact that the techniques are having on our environment.

Continuation
When we are not disturbed by the sand blasting, we can analyse the polishing at high pressure such as in the first track in Figure 1, and to optimise conditions to ensure the best possible polishing effect is obtained in the shortest possible time. Then it is time to attend to the problems of holes and cuts.