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  1. CompositeGeek

    TI Bolt substitute.

    Thank you very much for all the input! We eventually found an alternate Ti-bolt design that will meet our needs for a limited effectivity. FYI~It is a classic tail, tell the customer you will shut down his production line (for about a year) and it becomes AMAZING how much faster they open up...
  2. CompositeGeek

    How do I re-calibrate a composite reference standard?

    Yes Compositepro is describing the technique of making the kind of standard I was describing above. Composites and Airplanes - what was I thinking? There are gremlins in the autoclave!
  3. CompositeGeek

    TI Bolt substitute.

    Have need of replacement bolt. Bolt is titanium shoulder bolt, 0.5" diameter by 1" long, hex head. Aluminum pigmented coating. Bolt meets 100KSI Tensile requirement and 90KSI shear. Need a suitable replacement because it takes 2 years to get this by lead time. Suggested alternates? Or...
  4. CompositeGeek

    How do I re-calibrate a composite reference standard?

    There is nothing to calibrate or adjust. You can check for wear and tear or damage but that is it. You should have a technical dwg of the standard that showing location of built in defects used in NDT acceptance and set up. Then you inspect the standard using a tighter NDT requirement than...
  5. CompositeGeek

    How would I make a tube with multiple bend from carbon fiber?

    Depending on your rate of production you might consider plaster. That can be molded to your shape and then "broken out" (read beat it with a hammer, er...mallet, er...vibrating whatsis). With a flexible resin, and few plies, you can make parts pretty quickly without damage to the laminate...
  6. CompositeGeek

    Vacuum Bagging & Form Bracing

    Another reason to brace is to control the thermal changes in the mold during cure. If the geometry is highly critical I have found some bracing reduces the impactof CTE or "directs" the tool expansion and contraction during cure to yield the geometry required. Composites and Airplanes -...
  7. CompositeGeek

    COLUMBIA AIRFRAME OUTLASTS STEEL FATIGUE TESTING STRUCTURE

    I built the wings and wing box for the Columbia 300. they are fiberglass skins and ribs secondarily bonded with spars that are made of carbon uni-tape and fiberglass. The fuselage is primarily fiberglass and honeycomgb construction with localized carbon fiber element. It is a very interesting...
  8. CompositeGeek

    Surface Defects/Void Formation

    SS, I think C-pro has the right idea. I would use his technique to eliminate the issue about galvanic responses. Last suggestion, if the tooling is reacting to the resin, you might consider plating the tool with a nickel surface as an alternative to modifying the release agent you are using...
  9. CompositeGeek

    Surface Defects/Void Formation

    Samplesecond, It is not clear from your original statement if you are seeing porosity on both the internal and the external surfaces of your part or if the condition is primarily on one surface only. I have encountered similar problems with peculiar porosity conditions when using solid...
  10. CompositeGeek

    Extruder Screw Fatigue

    If you normally pull, clean and reinstall the screws at your facility then you may want to subject the screw to a dimensional check as well as a non destructvie test as suggested by dwightdixon. I would imagine the screw is changing shape over the course of its life. You may have an early...
  11. CompositeGeek

    Shear Strength of Vinylester

    Lots of those processing values are listed in www.matweb.com by commercial product name. Composites and Airplanes - what was I thinking? There are gremlins in the autoclave!
  12. CompositeGeek

    pinholes and surface defects of any kind

    Avior, You probably don't need to run a full DSC to understand the chemistry and behaviour of the resin. The material vendor should be able to tell you at what temp the resin starts to flow and what the viscosity is at that time. Some resins stay pretty gell like, others reach the consistancy...
  13. CompositeGeek

    pinholes and surface defects of any kind

    Avior, re your questions 1 and 2. 1. Generally speaking I am not a fan of films used to eliminate surface porosity. Mostly due to the increase in material costs (low usage at high price per pound), and weight impact. I tend to use them after exhausting other methods or to reduce paint prep...
  14. CompositeGeek

    pinholes and surface defects of any kind

    I have used sticky backed teflon tape on the surface of tools where surface pinholes were a large problem with great success. Particularly when I could not introduce a skin surface resin like Synskin, etc. You simply cover the tool with the material and butt splice all darts and splices...
  15. CompositeGeek

    Work order grading/scoring system

    Your Six Sigma guy needs to check his statistics books. He is asking to assign a percentage to an attribute variable. Its like saying your 45% pregnant. Bunch -o-BS. Instead if he wants a variable then set up with number of days early or late or number of hours early/late, etc. You could...
  16. CompositeGeek

    How to purchase a CNC laser machine?

    Yo Ifn, I suggest you make a short list of equipment manufacturuers. Prepare a few blank examples of the problem you are addressing - be prepared; give them materials, parts etc, that are the same as what you will use the equipment for. Then send them to your top 5 candidate vendors and ask...
  17. CompositeGeek

    How do you calculate reliabitliy factor (confidence interval)?

    There are a number of resources you can tap into for help in this arena. If you company employs a Quality Engineer AND that individual is a CQE, they have the necessary skills to help. Otherwise, contact your local chapter of American Society of Quality (www.asq.org) and see if there is a...
  18. CompositeGeek

    secondary bonding and aircraft primary structure certification

    SW reminded me! Thanks! I used to do a co-bond similar to the one described by SW composites for the A330/340 shroud box. Precured channel bonded into an uncured laminate. The process was abandonded later due to cost not due to any engineering issues. It was fully vetted through...
  19. CompositeGeek

    Laser guided Prepreg Layups

    Okay, Seats then: Oy, I envy you not, your volumes must be fun! I am not sure how much those systems cost anymore. When I did this they were very spendy. Probably a lot cheaper now. I do also recall that we had to think through carefully where we put them in the shop for part flow...
  20. CompositeGeek

    Carbon fibre and Aluminum, Thermal expansion

    Have you considered making the box edge a U channel instead of an L angle? Then the carbon will move within the channel. Composites and Airplanes - what was I thinking? There are gremlins in the autoclave!

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