Glafo, PG Vejdes väg 15,
Vejdes plats 3
Tel: 010-516 63 50
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Project leader: Maria Lang
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, 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
can read the first report and the background of the
You can read
the second report here.
After the introductory attempts made using an existing pump at the "Swedish
Waterjet Lab" it was confirmed that higher pressure is needed to
achieve shiny surfaces. During November 2009 a new pump was installed,
which means that we can conduct tests with up to 30 bar of pressure.
The test bench has been developed so that we are able to vary the pressure
of the slurry (a mixture of water and polishing agent), the speed of
the nozzle over the surface of the glass, the angle of the nozzle and
the distance between the nozzle and the glass to be polished.
The test bench.
We have purchased six different nozzles so far, but there are many more
that may be worth testing.
We also use various types of polishing agent. So far we have tested
Regipol (cerium oxide), Sillitin (aluminium silicate), aluminium oxide
and iron oxide.
A statistical experiment schedule for these parameters has been drawn
up using "Modde" software for designing experiments. The results
from trial runs are entered into the software. This allows you to see
which parameters have the most effect and which work well together.
The Ra value, which is
a measurement of surface roughness on the polished samples, has been
entered into the experiment design software Modde.
The lowest Ra value (= the finest surface) is in the blue area up to
This shows that on the samples run so far, a low speed nozzle over the
surface of the glass had the biggest effect in producing the smoothest
With some of the nozzles it seems that at high pressures there is blasting
of the shiny surface. Continued optimisation of the various parameters
Results of the tests performed to date show that we have more developing
We can see that it is possible to achieve a shiny surface but the results
are not sufficiently good to look at. The measurements we have got so
far using a stylus profilometer do not really match what we see with
our own eyes.
Selection and purchase of analysis equipment
When the various analysis methods were compared, what determined the
choice was that the interferometer can also provide a good image of
the surface to be analysed.
Bruker and Topnova have been asked to supply quotes for optical interferometers.
An interferometer can produce both an image and a calculation of the
With Bruker’s equipment it is also possible to use a confocal
objective, which means that it is possible to carry out measurements
on gently curved surfaces and on certain edges.
Samples are sent to all suppliers for sample measurement, and these
measurements, along with the price, determine which equipment we will
Another nozzle is to be purchased and tested.
Until now, polishing experiments have been carried out on float glass,
which is harder than crystal. Now there will also be tests polishing
ground plates of crystal.
Work is continuing on optimising the various polishing parameters.
Evaluation of the various instruments continues.
We will be testing the polishing of surfaces that have a finer ground
surface to start with than we have tested before.