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Are there stronger bolts?

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  • Are there stronger bolts?

    Is there a stronger bolt I can use better than a grade 8? What does"AN" desigination mean?

  • #2
    Nick, we use a Grade 9 at work. The only trouble is, the grade 9 is more brittle than the grade 8 and it will break quicker, however the grade 9 does have more holding stength.

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    • #3
      KBar........thanks for the comeback. How are they stronger? Shear load or enlongation(sp)or both............Nick

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      • #4
        I always heard that "AN" meant Army-navy... which is a standardized style of hardware and fittings.

        Also I have seen and have used Grade 9 hardware. Typically its only in a clamping situation as Grade 8 works great in shear and in tension. Keep in mind the strength and hardness of the hardware vs. the hardness of the material you are bonding. What will fail first? Is that catastophic failure? In high fatigue areas you often want your hardware to have similar properties as your clamped materials. Unless the hardware is only acting as a friction causing clamping force.

        Also grade B7 has a fairly high yeild value but with more of an elastic range than that of the typical Grade 8 hardware...

        Its more in the application of the hardware than in the actual strength of the hardware. You'd be amazed at what you can put Grade 5 and 8 through if you spec it properly.

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        • #5
          I am no ex-purt so take this with a grain of salt.

          Depends on what you are doing with it iin high stress apps. 120,000 psi is about as high as it goes for Steel bolts using ASTM ratings. That is grade 8. There are bolts that have been made from certain alloys and or are subjected to treatments that are grade 8 but have better high or low temp use.

          There ARE bolts that are higher that 120,000 psi but you might have to go out of the realm of steel.

          I was told that AN = Airframe - Navy

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          • #6
            Just browse through a McMaster-Carr catalog or Grainger catalog. There are some stronger bolts. Especially some of the alloy ones. Dave
            Originally posted by monte55 View Post
            Is there a stronger bolt I can use better than a grade 8? What does"AN" desigination mean?

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            • #7
              This pretty much answers most questions. http://www.unified-eng.com/scitech/bolt/boltmarks.html

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              • #8
                Originally posted by monte55 View Post
                KBar........thanks for the comeback. How are they stronger? Shear load or enlongation(sp)or both............Nick
                I actually prefer the grade 8 over the grade 9 because of the shear strength, the grade 9 will snap quick with a sharp impact or sizable load against it. But because of technical & liability issues, we need to use the grade 9.

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                • #9
                  FWIW, if you have trouble with bulk bin grade 8 bolts, take a trip to your local CAT dealer. They are known for quality fasteners.

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                  • #10
                    I am curious to know what hte application is. Generally if a grade 8 bolt can't handle the stress you need either more of them or a bigger diameter bolt.

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                    • #11
                      Supertanium fasteners have been around forever. In the smaller sizes they are 200ksi. I havent laid eyes on one for several years but I'm sure they are still available.
                      They are pretty common in maintenance departments of plants. The military used to buy a ton of them too.


                      JTMcC.

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                      • #12
                        AN is only available in fine thread. Grade 8 comes in coarse and fine.
                        -Just something to think about.

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                        • #13
                          Cap Screws

                          Hi Guys!
                          I think this is my first post but I read most of the comments. The reading is very interesting. Thanks to all you contributors!
                          My Premier Fastener Handbook shows the following:
                          SAE Grade 5 - three lines - 120,000 psi
                          SAE Grade 8 - six lines - 150,000 psi
                          Supertanium - special symbol - 160,000 psi
                          The psi is tensile strength and shear strength is about 60% of the tensile strength.
                          If you have a Machinery Handbook or similar reference it will have a section on fasteners but when you exceed grade 8 the data is usually from the manufacturer.
                          Happy Holidays!

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                          • #14
                            I would reference the AC43.13 manual for what the standards are (an,ms etc). Carol Smith has this book which i found useful ]

                            http://www.amazon.com/Fasteners-Plum...9710031&sr=1-1

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                            • #15
                              Originally posted by monte55 View Post
                              Is there a stronger bolt I can use better than a grade 8? What does"AN" desigination mean?
                              Ok, Im new to this forum so be gentle...

                              I was looking over this post and saw that no one had mentioned F911 bolts that have ratings up to 180,000 psi. I use F911's in off road applications such as suspension pivot points for a-arms, trailing arms, ect. Normally you can only find these at a "bolt specific" store meaning your local home depot does not carry them. In addition, F911 nuts are only available in pinch nuts not nylocks but you can you grade 8 nylock nuts on them.

                              If I had a nickle for every time I said "someone once told me"... I would be a rich man. Also consider fine thread grade 8's vs course thread for the side loading strength. Course threads take out up to 25% of the girth on a 1/2" bolt because of the deeper cuts for the treads.

                              As for AN... I use them but mostly for hydraulics and fuel lines. I have always known them as Army-Navy (someone else told me that also).

                              Below is a link about F911 bolts. Thanks for the original post because I just found a new place to buy F911's...

                              http://www.bolts4u.com/f911hm.htm

                              and

                              http://www.ababaqa.com/

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