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| Air-Cushion
Applications |
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| Product |
Application
Characteristics
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Density
(g/cm3) |
Flexural
strength
(N/mm2) |
Air
flow rates at pressure difference of 1 bar / 10 mm
METAPOR slab (per cm2 per minute in litres) |
| BF
100 AL |
Air-cushion
transport in paper industry, plastics and metal handling
|
1.8 |
56 |
1.4 |
CE 100
WHITE |
Air-cushion
transport in semiconductor industry, glass substrate
handling |
1.7 |
28,5 |
1.4 |
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Case Study at BASLER AG, Ahrensburg,
Germany – glass substrate transport
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| METAPOR® CE 100 WHITE hovercraft conveyor
system supplied by our METAPOR® distributor Horst Witte
Gerätebau, Bleckede, Germany |
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| METAPOR® CE
100 WHITE |
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Highly
sensitive products like glass substrate for flat
displays need to be handled extremely carefully
or even better not manually handled at all. The
Basler company took this to heart: Their quality
control specialists offer equipment with a hovercraft
transport conveyor belt system, which comprises
of Witte modules. The original application for
these modules was vacuum clamping.
One of the few specialists for such systems is
Basler AG in Ahrensburg near Hamburg. They develop
and manufacture vision technology - technology
of artificial viewing - and market it worldwide.
Depending on the application Basler specialists
adapt their quality control systems and components,
to optimise effectivity and economy of automatic
manufacturing. Basler AG customers stem from CD/DVD,
rubber, flat screen and foil industries. Next to
system solutions Basler offers components and supplies
for the machine vision industry with special cameras
and lamps
Basler manufacturing systems for displays without
automatic optical inspection systems, which are
integrated in the manufacturing process, are unthinkable.
They have to recognise faulty substrate early and
enable exclusion before following processes take
place. Permanent inspection also records changes
in manufacturing process, which can be reacted
to immediately (yield management).
The result: optimised output, reduced manufacturing cost and
faultless manufacture.
Conventionally, substrates are transported on
rollers or belts. This type of handling is still
warranted for lower quality requirements.
However on an absolutely high-tech level contact-free
transport is required. Substrates hover through
the manufacturing process on an air cushion so
to speak. The idea to use so-called air cushions
for transport is not new. This technology has been
used for a long time in the semi conductor industry
to handle wafers.
Usually the modules for making the air cushions
are in ceramic foam, thereby very expensive and
because of their hardness heavy and complicated
to machine.
Clamping plates manufactured out of porous aluminium-hydroxide
( METAPOR CE-100 WHITE) offer the advantage that
they can be easily machined compared to ceramics.
The material is ideal for us because it is more
or less self-cleaning. When METAPOR clamping
chucks come straight off the machine, it has pressured
air put through it and after 30 seconds all loose
particles are removed. During use with cleaned,
compressed air the plate is even suitable for clean
room conditions. |
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| METAPOR® CE
100 WHITE |
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After
extremely successful tests using Witte products
Basler had the process of transporting substrates
on air cushions during optical inspection with
line cameras patented and has applied it already
several times. Apart from it being operator friendly
the Ahrensburg vision specialists also profit from
the fact that they can define the required connections
or holes themselves.
Witte supplies individual modules suitably pre-machined
and Basler assembles them onto sub-structures.
It sounds easy. However the total alignment of
the modules requires a great deal of know-how.
Transport surfaces must be set absolutely plane
parallel to transport the glass substrates of approx
0,5mm thickness and an edge length of one meter
(increasing constantly) from machining process
to machining process. Also optical inspection systems
integrated in intervals require stable accurate
handling of the substrates.
The substrate “swims” on an air
cushion of approx. 1 millimetre on the edge of the
transport belt, which is powered along at a speed
of 6-12 m/min. The substrates are only touched on
the edges foreseen for this purpose. The reverse
side is not touched at all and all marks are avoided.
Further the air cushion conveyor comprises of a lower
number of moving components than conventional roller
or conveyor belts, which makes for easier service
and maintenance. |
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| METAPOR® is
a registered trademark of Portec in Switzerland. |
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