I agree - mostly. There are some types of spray systems where the
gun change is needed, and others that can handle a wide range of
viscosities without any hardware changes. I have some of both kinds in
production here.
One of the major hazards to watch out for with 100% solids coatings,
particularly silicones, is the atomization. Silicone, when atomized, tends
to migrate to all surfaces in the area around the coater - floors, walls,
other equipment, etc. That can be a huge problem.
It is a great recommendation to make sure that the equipment
manufacturer for the spray system has worked with the coatings that
you want to use, or at least something very similar, and has had good
results. They should be willing to give you a list of names of satisfied
customers that you can contact independently to discuss process
performance, technical support, etc.
The right company will give you very good results.
>>> Aric parr <[log in to unmask]> 04/17/98 06:18am >>>
I have at previous employers.
Changing the nozzle (or gun) is required if the viscosity changes beyond
the limits of the nozzle.
Some spray systems are incompatable with some of the newer coatings.
Moisture sensitive materials should not use systems where moisture
laden
air contacts the coating before it exits the gun (common on some types
of
atomization systems).
A 33% solids coating requires .006 in of deposit for .002 of coating
thickness, while solventless material only needs app. 1 mm of coating.
Some
nozzles cannot handle the lower flow rate.
Also, some suppliers do not totally understand the new coatings, yet.
In short, it depends upon the coating and the gun.
Aric Parr
-------------
Original Text
From: C=US/A=INTERNET/DDA=ID/TechNet(a)IPC.ORG, on 4/17/98 7:12
AM:
Hi Technetters
Can anyone provide information about experiences with new solventless
coatings on Selective Coating equipment.
Have you been obliged to change application heads or use special
dispense
pressures? We are trying to help out some customers who are receiving
conflicting information and would appreciate any TechNetter input
Kindest regards
Graham Naisbitt - Concoat Ltd
Alasan House
Albany Park
Camberley, Surrey GU15 2PL UK
Tel: +44 (0) 1276 691100
Fax: +44 (0) 1276 691227
E-Mail: [log in to unmask]
Regards, Graham Naisbitt
Concoat Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL
UK
Phone: +44 (0)1276 691100
Fax: +44 (0)1276 691227
email: [log in to unmask]
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