investment casting???

[kilotanker22]

i hear that ruger makes their recievers by investment casting.

what exactly is this?

[44 AMP]

Its also known as the "lost wax" method.

Essentially, the part is formed from wax. Then a mold is made around the wax part. Then molten steel is injected into the mold, melting the wax (which runs out a vent) and when it cools, you have a steel part.

This process, done right, leaves you with a nearly finished steel part, one that needs far less machining to become fully finished than a forging does.

Forgings are stronger than castings, of identical size. Prior to Ruger, casting (of all types) was used only for low strength parts, and in general, "cast" meant low quality. Ruger proved that wrong a long time ago.

Even the best investment casting has some drawbacks, compared to forgings. But it has big advantages in many ways, too.

[Bart B.]

Winchester 70, 670 and 770 receivers were investment cast starting in the mid 1960's. Their first push feed actions. Very strong, too

[FrankenMauser]

Essentially, the part is formed from wax. Then a mold is made around the wax part. Then molten steel is injected into the mold, melting the wax (which runs out a vent) and when it cools, you have a steel part.

Pine Tree Castings (Ruger's casting branch) actually uses the proper 'lost wax' method. Once the ceramic shell is solid on the wax tree, forming the mold, they bake the mold to harden it and warm it up for casting. At the same time, the wax is lost. So, by the time the molten alloy is poured into the mold, it's just full of air.

[kilotanker22]

Gotcha

Must be pretty cheap and efficient to do it that way

[SIGSHR]

Ruger's quality control has always been excellent, IMHO. Careful selection of the metals used combined with careful machining (?) of the molds allows for a high degree of uniformity and close tolerances.

[Art Eatman]

http://en.wikipedia.org/wiki/Investment_casting

[kilotanker22]

thanks art

[buckhorn_cortez]

Must be pretty cheap and efficient to do it that way

That's a misconception that casting is cheaper than forging. There is a metal die that is made and the wax is injected into that die to make the wax part. The metal die is as expensive and in some cases more expensive than a forging die.

In shorter run parts, the die may be made from plastic - which, in turn, needs to be replaced more often than a steel die. In either case, there is a lot of precision machining that needs to be done to create the die.

Like a forging die, the casting dies have to be replaced at specific intervals to keep the tolerances as needed for the precision molding.

There is also a lot of hand work involved with assembling wax molds into trees, dipping the parts into a ceramic slurry, covering it with sand, and repeating the process until the ceramic coating is the correct thickness.

The casting process itself may include heating the mold prior to casting, rotating the mold as the metal cools, and a number of other processes.

[kilotanker22]

So if it is not necessarily cheaper it must be efficient in turning out a large number of quality parts in less time otherwise why use it?

I know a comparable win model 70 is around 200 dollars more than the ruger. So that is kinda where I got the cheaper comparison because they are two very similar actions with different manufacturing processes.

[jmr40]

In the long run it is cheaper to make parts by investment casting vs forging. Yes you do have some investment in the equipment and dies must be replaced with casting. But you also have to invest in machinery that wears out with forging. Cast parts come out or the dies much closer to the final shape and require much less machining to get them down to their final size and shape. It is much less labor intensive and easier to do with automated machinery. This reduces labor costs which are usually the biggest expense to build any product.

I think Ruger has pretty well proven that cast parts can be just as strong as forged and machined parts. One argument, and I'm undecided on which is correct, is that cast parts must be thicker to achieve the same strength. I don't know if that is fact or not, but Rugers do tend to be thicker and heavier than comparable guns made by forging.

At any rate I have no problems with Rugers cast parts. I'd trust them to work. In fact I consider the Ruger Hawkeye series of rifles to be the most rugged and dependable bolt rifles made. All things being equal I've found the Wincehsters to be closer to $100 more expensive and prefer them because I've found them to be more accurate and a bit better finished etc. But the Rugers would be a strong 2nd choice for me. I give no 2nd thought to the casting vs forged difference.

[jaguarxk120]

The Ruger No.1 rifle is also investment cast and has been rebarreled to any caliber that can be fitted to the action. If Ruger made a larger single shot action it would come in 50 BMG.

[kilotanker22]

I have a ruger 77 hawkeye 270. It shoots pretty darn good. Actually I had never shot it till recently and now it is easily one of my favorites.

I did notice when I pulled it out of the stock that the metal was not as nicely finished but all the finish you can see when the rifle is assembled is perfect. I really like the action it is not the smoothest but is smooth enough and feels substantial in the hand. Also I have been told that the LC6 trigger was not good but mine is dandy for a hunting rifle.

All in all I think that ruger puts out a great product with good attention to detail at a very competitive price.

I do however really like the Winchester action matter of fact I plan to buy a featherweight in 270 one of these days.

We'll to be honest I have been finding myself to be quite fond of controlled round feed actions these days

[madmo44mag]

Interesting this thread came up.
I understand what investment casting is and what the pros and cons are.
A while back AIM offered investment casting 5.56 BCG for a low price of $ 79.95.
I have done business with Aim for years and trust their quality and what they advertise.
I was building another AR platform gun and decided I would try their BCG.
As of today I have almost 1500 rounds down that rifle and the BCG looks better than some of my high end BCG’s.
The body shows almost no wear, the bolt looks almost new.
I am very surprised at how well this BCG is wearing and performing.
When done right investment casting are a good value.

[44 AMP]

With casting, there is always the possibility of voids (bubbles) in the material. With forging, the "grain" of the metal is "lined up". (real technical there, huh?)

SO, to ensure the cast part is at least as strong as a forged one, they tend to be thicker. And most designers, go beyond "at least". Ruger knew his revolvers would have to be a bit bigger than others, because he was casting the frames. SO he went and made them even bigger yet, which is why Ruger are called "tanks".

You can make very high quality cast parts the same size as forged ones, and still have them be plenty strong enough, even for rifle receivers. Many do.

Those who do not are where the cast = bad comes from.
And there have been a lot of them, over the years...

[James K]

Casting got a bad name years ago when cheap Spanish handguns, made of "pot metal" were imported by the ton and blew up almost as fast as they came off the ships. The problem was not casting itself, but the material from which they were cast.

There is some notion that the term "pot metal" refers to some kind of alloy melted in a pot. It doesn't. It refers to the material cooking pots were made from, cheap cast iron that was flawed and brittle, and very prone to break under pressure.

But those guns put the kibosh on the use of casting for guns for many years, until Ruger, using good material, and good production techniques, showed that cast guns could be strong and serviceable. (Though many cast Ruger parts are thicker than forged parts used by other makers, in order to have the same strength. This leads to such siliiness as "no one can blow up a Ruger", when quite a few people have, often because they believed nonsense.)

Casting is not always cheaper than forging, but it has the advantage of requiring less capital investment and less of a factory environment. Forging requires large presses that have to be quite literally sunk into the ground, and which shake the building when operated. Casting can be done in a shopping center. Also, investment casting, unlike MIM, still requires machining to final dimensions, almost as much as forging. But MIM, while fine for small parts, is not (yet) feasible for larger units.

A note on the Winchester Model 70; the modern Model 70 receiver, AFAIK, is made from a forging. Pre-64 Model 70's, were machined from bar stock.

Jim

[mete]

You have to look at the whole picture .I have an impellor for a jet aircraft which rotates at 90,000 RPM The blades are not machined after casting !
Ruger's system is one where macining is minimal after casting also .That's where the savings come from .The actual investment casting is expensive.You can't just take a normally forged , machined ,part and change to cast .