Glafo, PG Vejdes väg 15,
Vejdes plats 3
Tel: +46 10 516 63 50
a map at the
"about Glafo" page.
Project leader: Christina
Project status: on-going project
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, cuts
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
can read the first report and the background of the
You can read
the second report here.
You can read
the third report here.
You can read
the fourth report here.
You can read
the fifth report here.
We have now produced polished grooves that, under visual inspection
has the same quality as the acid-polished surfaces, which means that
we have achieved the surface smoothness that had been aimed at. However,
the method is still quite slow, with the best results being achieved
at a speed of 2 mm/second.
The maximum pressure
that we can achieve with any of the pump that we have is 50 bar. With
a higher pressure, we could polish more quickly. We have investigated
the market to find a pump that can pump slurry containing a high concentration
of polishing abrasive. The first potential supplier withdrew when he
realised that our application was not what the pump was intended for.
We will now try an alternative pumping technology, which will hopefully
allow us to perform polishing trials at a higher pressure.
When the project
started, we investigated various polishing abrasives, but had difficulty
in interpreting the results as the glass was seriously affected by blasting.
In the most recent trials, we have found that aluminium oxide is more
effective than cerium oxide: see Figure 1. These trials have been carried
out with various nozzles, but at essentially the same pressure.
Pressure and speed
have shown themselves to be very important; more so than the effect
of the nozzle. It can be seen from Figure 1 that there is a substantial
difference between the quality of the surface polished with cerium oxide
and that of the surface polished with aluminium oxide.
The results of
visual assessment are rated on a scale of 0 to 5, with 0 indicating
no visible change, and 5 equivalent to an acid-polished surface. In
the picture below, the cerium oxide-polished surface has been rated
at 3, and aluminium oxide-polished surface at 5. These ratings are in
good accordance with what we see in the optical profilometer.
Figure 1. Left:
a surface polished with a 0,5 mm nozzle, 48 bar pressure and 50 % cerium
oxide slurry. Right: a surface polished with a 1,3 mm nozzle, 45 bar
pressure and 50 % aluminium oxide slurry. Magnification: 2,7 times.
Click on the picture to enlarge it.
and mechanical assessment of unpolished holes
The strength of unpolished drilled and water-cut holes has been investigated,
finding that the drilled holes were stronger than the water-cut holes.
Ultrasonic testing gave the same result. To be able to polish the 'interiors'
of the holes, we need greater flexibility than we have in the prototype
test rig, and so we shall mainly use an ordinary water cutting machine,
as shown in Figure 2.
Figure 2. A five-axis water cutting machine.
The pump will be moved close to the water cutting machine. A tray to
collect the polishing slurry will be made and positioned on the water
cutting table. When this has been done, we shall start polishing the
holes and then examine them by ultrasonic inspection. Finally, the strength
of the material will be determined.