New Experiences...

This is a discussion on New Experiences... within the Defensive Carry Guns forums, part of the Defensive Carry Discussions category; MIM sear mag catch disconector plunger tube CAST safety lock grip safety FORGED slide receiver barrel slide stop MACHINED from bar stock hammer all pins ...

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Thread: New Experiences...

  1. #16
    OD*
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    Recent Colt parts

    MIM
    sear
    mag catch
    disconector
    plunger tube

    CAST
    safety lock
    grip safety

    FORGED
    slide
    receiver
    barrel
    slide stop

    MACHINED from bar stock
    hammer
    all pins
    bbl link
    bbl bushing
    trigger fingure piece
    ejector
    firing pin
    firing pin stop
    extractor

    This process would be the same for all the 1911s.
    Not true of the Norinco's, sadly.
    Last edited by OD*; October 23rd, 2005 at 11:35 AM.
    "The pistol, learn it well, carry it always ..." ~ Jeff Cooper

    "Diligentia Vis Celeritas"

    "There is very little new, and the forgotten is constantly being rediscovered."
    ~ Tiger McKee

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  3. #17
    Senior Member Array A1C Lickey's Avatar
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    I realize that this will expose my ignorance, but what does MIM mean? And what are the disadvantages of a part being MIM?

    A1C Lickey

  4. #18
    Senior Member Array rfurtkamp's Avatar
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    Quote Originally Posted by Bruces45
    Once you own one I will give ya a week and you'll have changed your mind and want to be top on my "list"
    I used to own two. I sold one to get my first Glock. I shoot the Glock a heck of a lot more.

    I did a 45 shoot last week. The 1911 wasn't as pleasant to shoot as my S&W 4506 or the HK USP, although I can hit what I want with any of 'em.

    I've owned one for years and haven't been converted. Ditto with the Browning Hi-power.

    They're nice guns and deserve a place in my collection as historical landmarks, but they're like my top-break Webley and the Schofield clone: interesting pieces of history that I can shoot.

    No way do I want to bring any of 'em to a gunfight.
    Driver carries less than $45 worth of remorse.

  5. #19
    OD*
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    Metal Injection Molding

    http://www.megamet.com/tut.htm
    "The pistol, learn it well, carry it always ..." ~ Jeff Cooper

    "Diligentia Vis Celeritas"

    "There is very little new, and the forgotten is constantly being rediscovered."
    ~ Tiger McKee

  6. #20
    Senior Member Array A1C Lickey's Avatar
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    Okay, so I understand what MIM is, but I'm not too sure if I see the disadvantage.

    A1C Lickey

  7. #21
    VIP Member Array maclean3's Avatar
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    I spent a few years in a Tungsten Carbide plant and a fair bit of that time was spent in the injection department, I'll offer what input I can:

    In order to make the process of injection work, at least with carbide, the material is mixed with a series of waxes and heated to melting point, poured into a reservoir (looks like a vertical cement mixer) and then shot under air pressure into a mould. A few seconds later the mould is cracked open, parts are removed, deflanged and run through a cold isostatic press (to check for voids and cracks).

    The next step is dewax: A staged program in a wax absorbant media (we used kaolin clay) that heats the parts and draws out the majority of the wax. From here the parts get declayed, deburred (mould seam lines, cut-off lines, etc.), trimmed etc. - we used steel wool and razor blades, highly technical process .

    Furnace is next: Sintered process took us roughly 1 to three days. Straightening runs through the furnace were almost always required due to the deformation caused during wax loss, part shrinkage, etc. Then into the hot isostatic press - further protection against voids and cracks. The primary difference in the two is cold pressing is done in water and voids tend to cause catastrophic parts failure (better on the manufacturer's end than during use by the consumer, right?), hot pressing is done under pressure in inert gas such as Argon. "HIP" runs can cause smaller voids and cracks to seal themselves and save the parts.

    Parts are then ground to correct remaining warpage, out of spec parts and such.

    The biggest problems with injection moulded parts are:

    - There are ALWAYS some voids that slip through QC. No amount of testing will detect all of them but they will inevitably fail under the stress of constant use. The cause of the voids? Heh, using air to force the material into the mould in the first place!

    - Blending wax with heavy metals causes inconsistencies in material densities (even within the same part). Out of spec density changes the RC and shrinkage rates of the material. Too low Rc and the part wears too quickly, too high Rc and it destroys other parts that wear on its surface.

    - The entire process lends itself to parts warpage that most would find unbelievable. Straighten runs and stress relieving in the furnace only help so much.

    - When QC spends 10 to 15 hours a day inspecting parts under a microscope those hairline cracks get mistaken for mould seam lines very easily.

    Can you GUESS what my opinion is of injection moulding?
    Oh, BTW, that was the SHORT version!
    Jack

  8. #22
    VIP Member Array Bud White's Avatar
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    Good Post i have used injection molding with plastics so i understand how MIM work and same problems came up with plastic

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