Manufacturing Aluminum Masts

Discussion in 'Boatbuilding' started by Mikey2, Mar 30, 2007.

  1. Mikey2
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    Mikey2 Junior Member

    Hi.

    I am doing an assignment into the mast and the materials used and the manufacturing process and have a few question I hope you can help me with.

    1. What Alloys are added to the Aluminum masts if any?
    2. On larger masts the top is tapered, is this done by hand once the mast has been extruded? Or is this done by a different process?
    3. Does anyone know of the quality control checks that would be carried out when manufactured?

    Thanks.
     
  2. FAST FRED
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    FAST FRED Senior Member

    Masts are EXTRUDED one piece usually from 6061T6.

    They are hand cut and welded to taper the top.

    BIG factory required for extrusion process!

    FF
     
  3. Mikey2
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    Mikey2 Junior Member

    Thanks for your response.

    Does anyone know of the treatments carried out once extruded?

    I read somewhere they are primed and top coated using Awlgrip polyurethane finishes...
     
  4. Greybarn
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    Greybarn Junior Member

    The treatment depends on the application. If the masts are for one-design boats, then they are typically anodized. In the old days, (15 years ago), if the mast was for an ocean-going racing sailboat, then no extra paint was applied as it added unnecessary weight. If the mast were for a yacht, then the aluminum would be painted with some sort of linear polyurethane paint (Awlgrip, Imron) and would be prepped accordingly (alodine wash, zinc chromate primer, undercoat, LP paint).
     
  5. Mikey2
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    Mikey2 Junior Member

    O rite thanks. Would this be done by hand, or would it be sprayed on automatically once extruded?
     
  6. Greybarn
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    Greybarn Junior Member

    This would be done by hand after all the fittings have been fit to the mast. All of the fittings are drilled and tapped, countersunk etc,the winch pads are attached, the mast is tapered, and welded. everything is then taken off hte mast and then paint procedure is started.
     
  7. Mikey2
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    Mikey2 Junior Member

    Does anyone know of the quality control checks carried out?

    Also when you say everything is taken off? I read somewhere that it is difficult to weld when the mast is given its final treatment? Or are the fittings attached another way?
     
  8. RHough
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    RHough Retro Dude

    Masts are not usually welded after they are anodized. If the mast is tapered, it gets tapered before it is anodized. Tanks big enough to anodize masts are fewer and farther between than they were 10-15 years ago, so more masts are painted these days.

    When we taper a section that has been anodized, it gets painted after the taper is welded. The same goes for any welded repairs. A good weld requires clean metal, so the anodized surface must be ground off before welding. The welded joint should be protected by a new surface treatment. Paint is more practical than having the mast anodized again.
     
  9. Mikey2
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    Mikey2 Junior Member

    So from what I've learnt, the process goes as following...

    1. Aluminum 6061T6 Billets are melted down and extruded through the mast cross section die.
    2. The extrusion is then cut to the length required.
    3. The top end would be cut and tapered and welded.
    4. Any other holes and fixings would be cut out.
    5. The mast would then be anodized.
    6. Mast would be prepped (alodine wash, zinc chromate primer, undercoat, LP paint).
    7. Final finish coat applied: Awlgrip.
    8. Any screw holes chased.

    And thats how a mast is manufactured. Is this correct? Have I missed something? Or got something wrong?
     
  10. ted655
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    ted655 Senior Member

  11. FAST FRED
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    FAST FRED Senior Member

    # Aluminum 6061T6 Billets are melted down and extruded through the mast cross section die.

    The mast builders usually OWN the die for the extrusion ,(not the extrusion shop) so the sections are trimmed to their requirements.

    # The extrusion is then cut to the length required.

    Owning the die allows some competition to lower costs , and some roll the sail into the mast extrusions are 2 parts or more and the result is a really heavy mast.

    FF
     
  12. Mikey2
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    Mikey2 Junior Member

    This I understand

    This I don't understand, why would you put the sail in the mast? The only thing I can see is it saves space in the factory...
     
  13. ted655
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    ted655 Senior Member

    Like a window shade. Alot of light, or a little light. Same with wind. Most are operated from the cockpit or cwheelhouse. Great for large boats with few crew or single handing.
    Also gives UV proyection when at docked.
     
  14. allan white
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    allan white Junior Member

    Mikey2,
    A minor clarification is that aluminum is not actually melted prior to the extrusion process. I believe it is heated to +- 900F and then pushed thru the die by an extremely powerful hydraulic press.

    allan
     

  15. Mikey2
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    Mikey2 Junior Member

    Ah, Ok thanks.

    The primer coats and final finish, is this applied by brush? Sprayed on?
     
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