Investment casting

Discussion in 'General Firearms Discussion' started by duster066, Nov 13, 2017.

  1. duster066

    duster066 Supporting Member

    "Everybody" (that means maybe not you) trashes investment cast 1911s. I have one. It looks like an A1, the one I wanted, and it goes bang. But no one trashes Rugers. I looked awhile back and lots of cool stuff is made with investment casting.

    A while ago I got a wild hair and just had to know all about jet turbine blades. Google? Turbine blades are truly made out of unobtainium, wild alloys. They melt it in trick furnaces, and pour it into investment casting molds.And the we all ride on them at 500 mph.

    "No one" bitches about that.
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  2. Rachgier

    Rachgier Administrator Staff Member

    Cast, forged, billet. Pros and cons to all 3, snobs for all 3. It's kind of like mil-spec. Just because it says mil-spec doesn't mean it's good. It just fits a certain tolerance criteria.

    I know a lot of gearheads that buy something because it's billet but don't acknowledge that it's as much about the quality of the material used to create the part that gives it it's strength, as it is the process that was used to create it.

    I wouldn't turned down a cast 1911 frame.

  3. duster066

    duster066 Supporting Member

    I'll probably make this one do super. Get the springs, shoot the boolets, what the heck. A Hi Point can do it. Lol
  4. ajole

    ajole Supporting Member

    NE Utah
    People look at "cast iron" and how it is relatively brittle, and then get stupid.
    Of course, cast iron is GREAT for certain things, and pretty tough in many ways.
    Forged metals are stronger than cast in the same material, no doubt...but cast is plenty strong enough for many uses. I wouldn't want a cast barrel, but the rest of the gun parts? Probably not a big deal.
  5. MaryB

    MaryB Supporting Member

    I have seen milled parts fail because of the grain in the metal being a weak point, forged can have inclusions that cause weakness, cast can be brittle... all have issues that have to be controlled so they can be used.
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  6. duster066

    duster066 Supporting Member

    "They" said cast cranks were better in Street Stocks. Our revs were limited by head and cam rules, no need for forged. When a forged crank hits a wall at 6000 RPM it might break. Cast cranks are said to be more malleable and survive the walls better.
  7. greg_r

    greg_r Lifetime Supporter

    Wonder what would happen if you racked a slide 6000 times per minute? Just sayin'.

    Cast=molten steel poured into a mold
    Forged=semi molten steel pounded into shape
    Milled=bar or round stock cut to shape

    Either is sufficient strong to do the job I think. Probably more potential for error or shoddy work with cast. FWIW, nearly every loading manual has a section labled Ruger or T/C only. Those guns are cast????

    I also wonder about the strength differences. I used to frequent a steel mill. Loaded strip steel and billets. The steel was liquid at one point and they had a machine that sort of stretched red hot steel. Extruding I think. I know nothing about making steel, but what's the difference between melting steel to make a billet and melting steel to pour in a mold? They were both liquid at one point???
    Last edited: Nov 15, 2017
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  8. What about Metal Injected Molding; or Sintered powdered metal?

    Casts are cheap and quick, depending on exact process. You have lost-mold casting (often used with sand or similar molding medium);
    And then you have investment casting; using durable molds that are milled, usually rough milled, because the final finish might require more milling or surface grinding.

    The most labor intensive method is billet machined, quickest is CNC milled but manual milled can give you some degree of freedom, especially with weird angles and tolerances.

    Forgings... that itself can be stronger, but depending on the alloy mixes, may be more brittle, or more ductile than simply cast; and there are two forging methods I know of, but the details escape me, cold hammer forging and hot forging.

    And we are also now developing molted metal 3d printing I believe; which might be the way to go for some components.... especially obsolete firearm parts (howboutdat.... a modernized semiauto replica of say, a MP1928... or Lanchester.. )

    Truly we are in an age where making metal items are easier and faster than before.

    I would wait and see how things go.... our beloved Hi Points are made using castings and stampings as well as injection molded plastics... with little milling and forging done (barrels, firing pins and bolt faces/chambers)
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  9. MaryB

    MaryB Supporting Member

    Sintered metal 3d printing, Chinese are using it to produce fighter jet frames! Powdered metal is laid in place then laser fused to melt it in place. This was 3-4 years ago when I saw the video of them making an entire jet fighter frame as one piece. Super strong...

  10. lklawson

    lklawson Staff Member

    Casting takes a lot less effort and energy. It can also be be chemically tailored to allow for greater or lesser ductility and malleability. However, it is vulnerable to inclusions and certain casting errors.

    Milling takes more time and energy but largely removes issues related to inclusions. It can also allow for much greater detail in the making of the part. However, it can create structurally vulnerable points of grain runout. Steel has a "grain" structure, a little bit like the grain in wood. If you carve wood cross-grain, you know that you've just put a weak point in it where the wood is more likely to break. Some steel can be like that. It's less obvious, and less likely, but still a possibility.

    Forging takes the steel and moves it around so that there is no grain runout, sort of like steam bending wood. But it takes even more time and energy. But if it's done wrong or has the wrong heat treat, then it can create other problems such as ruining the grain structure or forging in unintended weak points. In general forging is the strongest, must technically flexible option but it is the most expensive in terms of time and energy consumption.

    All of these options can be enhanced with tailoring of the steel using specific trace elements.

    I've done a lot of reading and research on the chemistry and construction of iron and steel because of my interest in swords and knives. I have a friend or two who are cutlers, swordsmiths, and blacksmiths. When I first started looking into this, I thought it was easy but, no, I was completely wrong. To really track it down deep, you need an materials engineering degree or a doctorate.

    Peace favor your sword,
  11. duster066

    duster066 Supporting Member

    One of my flight instructors was a metallurgical engineer. In a prior life he designed hot sections for Garrett AiResearch turbines. He could explain how hard metal science is.
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  12. ajole

    ajole Supporting Member

    NE Utah
    "Largely removes issues" is the key phrase...

    Our machine shops run into voids every once in a while when milling...pretty irritating when you do a 30 minute process, and pull it out of the cabinet to find a hole in your part. Admittedly, it's rare.

    Just to throw in other can peen the cast or even milled stuff to give it an "almost forged" surface, it does add some benefits, Wiki says it can make the parts last 10 times more cycles. That means a part that normally fails after 250,000 cycles could last 2.5 million cycles.
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  13. lklawson

    lklawson Staff Member

    Yup. That's because the process of making stock of steel is a essentially a lot easier than preventing the voids and inclusions than doing it "small scale" by casting.

    Depends on the application. :)

    Peace favor your sword,
  14. duster066

    duster066 Supporting Member

    There is no step that can be cheated to produce good metal parts and structures. The DC-10 that crashed into an Iowa corn field threw a fan section on the middle engine. Forensics showed the hub of the fan had an inclusion in it that had been there since the part was form. Numerous opportunities were missed to find the inclusion. The system failed on that one from start to finish.
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