April 22, 2008 by cimini
There was one lat question on today's session 3 that could not be addressed
by the speaker, Prof. Antonio Miravete. The question was:
"Can you comment on cleanliness requirements of the different processes?"
I asked Prof. Miravete to make a brief comment on this question here on the
Forum.
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In the prepregging process,
In the prepregging process, collation or lay-up of plies should be performed in a clean room in order to reduce the risk of contaminating the prepreg. The clean room is an environmentally controlled facility where, in addition to the control and monitoring of temperature, humidity, air pressure, air distribution, and air velocity, conditions are established to minimize the introduction, generation, and retention of airborne particles. Usually, temperatures range from 65 to 75F and humidity content between 24 and 64%.
In the rest of the processes, humidity content and temperature should be controlled in order to have adequate fiber impregnation and part finishing. Resin properties such as gel time, pot life, viscosity and reactivity vary with humidity content and temperature of the environment. The maximum and minimum values of these parameters depend on the resin type and supplier. For instance, if the temperature of the shop is too low, the viscosity of the resin may be too high and the fiber wetting may be incomplete. Similarly, if the humidity content is too high, the resin can suffer degradation and lead to premature failure of the part.
Antonio