Per our conversation earlier today regarding teledyne conf coating issue, I contacted Fred Gross for some answers. See Below for issues and solutions.
1) 4 hr Bake out of Assembly prior to coating. Bake out to be 4 hrs @ 93C.
* Per Fred Gross the 60 minute cure @ 125c prior to coating is equivalent to the required 4 hr
2) Measuring the thickness after application can be achieved by several methods:
* Using a coupon for measuring the cured material
* applying tape to the edge of the assembly and measuring tape after application
* Using a wet thickness gauge.
Fred has provided us with information for the gauge manufacturer.
3) The thickness requirement for polyurethane is .001-.005 per NASA-STD-8739.1
* If for some reason Teledyne cannot meet the .005 maximum thickness requirement there needs to be
a deviation waiver submitted stating that the requirement cannot be met and some mass and design
evaluations will be required. Hopefully with the proper tolls the thickness measurements will be
easier to obtain and will meet the specified requirements.
4) The use of an Ultra-Violet light source for inspection.
* The material being used contains the light tracer needed to perform ultra-violet inspection.
Therefore, the only materials needed would be the actual light source the Darkened area in
which to perform the inspections. Additional training will be required for all
personnel that will be performing the inspections.
5) All acceptance and rejection criteria shall be derived from either NASA-STD-8739.1 or the
amended document that Nick Virmani sent you referencing the J-STD series for assembly and coating
applications. There are some requirements not called out in the amendment that need to be included
( coating thickness ). Please use both documents when detailing a process for Teledyne conf coating
Please let me know if I can be of any further help in establishing this process.
Tracy L. Shepherd
Sr. Quality Engineer
GSFC-NASA Mission Assurance
GLAST Large Area Telescope Project
Stanford Linear Accelerator Facility
2575 Sandhill Rd.
Menlo Park, Ca 94025