FAQs

Cencho contains other products and information you need, so please check it out.

1

What Alloys Can Be Poured As An Investment Casting?

Generally all ferrous and non-ferrous materials can be investment cast. On the ferrous side, carbon, tool and alloy steel along with the 300, 400, 15-5PH and 17-4PH stainless steels are most commonly poured. Most aluminum, copper base, and other non-ferrous materials can be cast.

In addition, there are the &#;exotic&#; alloys used primarily in the aircraft engine industry to produce blades and vanes. These alloys are primarily composed of nickel and cobalt with a variety of secondary elements added to achieve specific strength, corrosion and temperature resistant properties.

2

What Size Range Of Parts Can Be Produced By The Investment Casting Process?

Investment castings can be produced in all alloys from a fraction of an ounce (such as a dental brace for a tooth) to over pounds (complex aircraft engine parts). Of the approximately three hundred investment casting foundries nationwide, most cast parts in the ounces to 20 pound range. Presently a larger number of foundries are increasing their capability to pour larger parts, and pieces in the 20-120 pound range are very common. Becker Metal Works does parts from 1/4 oz. to 80 lbs.

3

What Are The &#;As Cast&#; Dimensional Tolerances I Can Expect?

Typically, a linear tolerance of ±.005 in/in is standard for investment castings. This varies depending on the size and complexity of the part. Subsequent straightening, or coining procedures often enable even tighter tolerances to be held on one or two specific dimensions.

A concerted initial effort between the customer and the foundry's engineering staff can often result in an investment casting drawing for a part that substantially reduces, or completely eliminates the previous machining requirements to produce an acceptable part.

4

What Type Of Surface Finish Can I Expect From An Investment Casting?

Since the ceramic shell is built around smooth patterns produced by injecting wax into a polished metal mold, the resultant casting finish is excellent. A 125 microfinish is standard and even finer finishes (63 or 32) are not uncommon on aircraft engine castings.

Each foundry has its own standards for surface blemishes (positives, negatives), these are discussed and agreed upon with the customer based on the function and cosmetic requirements of the part prior to release of the tooling order.

5

Aren&#;t Investment Castings Expensive? If So, How Can They Save Me Money?

While investment castings are generally more expensive than forged parts, or those produced by other casting methods, they make up for the higher cost through the reduction of machining achieved by the near net shape tight tolerances that can be held as cast. Many parts that require milling, turning, drilling, and grinding to finish can be investment cast with only .020 - .030 finish stock. Again, it is imperative for the engineering staff of the foundry and the customer to get together and discuss what can, or cannot be cast to determine final finishing requirements and the potential cost savings.

6

How Many Pieces Do I Need To Make Buying An Investment Casting Practical?

Not as many as you would think! Tooling amortization is a key factor in determining whether, or not an investment casting is practical. The machine tool industry will often specify an investment casting on 25 pieces of a new part. This is bought once and after that only one or two pieces at a time for replacements. Conversely, quantities exceeding 100,000 parts per month are produced by some foundries largely for automotive use. The bulk of investment castings produced fall in the 100-10,000 piece annual range.

7

What Type Of Tooling Or Pattern Equipment Is Necessary?

Typically, a split cavity metal mold is manufactured that is the &#;female&#; mold from which the &#;male&#; wax patterns are produced. Depending on the complexity of the casting, various combinations of aluminum, ceramic or soluble cores may be employed to yield the desired configuration. Most tooling for investment castings fall in the $1,000 - $10,000 category.

8

What About The Integrity Of An Investment Casting? Will I Have Problems With Porosity And Shrinkage That Is Usually Nonexistent In Bar Stock Or Forgings?

Investment castings are used for many critical applications that require the parts to be x-rayed and meet definite soundness criteria. The integrity of an investment casting can be far superior to parts produced by other methods.

9

What Are The Lead Times I Can Expect When Ordering An Investment Casting?

Lead times depend primarily on part complexity and foundry capacity. Generally 6-12 weeks is typical for tooling and sample castings and 6-12 weeks for production.

If you&#;re fabricating parts out of bar metal, chances are it&#;s costing you a lot of extra time and money. If those parts require extensive machining, you could be losing significant money in scrap, especially if you&#;re using pricey metals or alloys.

An increasing number of shops that make metal parts that are intricate, require extensive machining or are produced repetitively or in limited quantities, are finding that investment casting is the ideal solution.

Investment casting offers a variety of alloys while saving finishing time and material waste. The process can also enable a company to combine two or more parts into a single piece, saving on fabrication, welding or assembly and machining time. The range of metals and alloys that can be investment-cast is broad, including low-cost alloys such as carbon and many tool steels or costly alloys such as aluminum, stainless steel, hastalloy, cobalt and Inconel.

When it comes to making metal parts, investment casting can provide a high return on investment for your shop and customers. Somewhat overlooked today, investment casting&#;forming metal parts in disposable molds&#;offers opportunities to create &#;near-net shape&#; parts of virtually any metal, even in low quantities.
Investment casting is an ideal process for those who fabricate or use metal parts repetitively, whether intricate shapes or components that require precise tolerances. If those parts weigh between 1 ounce and 30 pounds, they can be investment-cast in close tolerances with surfaces that require little finishing.

As opposed to forming parts from bar metal, investment casting is also beneficial for fabricators who want to combine components into a single piece or use pricey metals and want to avoid wasted material while minimizing machine time, which can run $85 to $100 per hour including machine cost.

&#;I suppose that some fabricators look at the somewhat higher initial cost and don&#;t realize all the savings of investment casting in time and materials, saving money in the long run. Plus, they can produce a better part,&#; says Carl Johnson Jr., vice president of Staten Island Machine Shop Inc. (Staten Island, New York).

Mr. Johnson, whose shop produces metal shafts as well as plate and sheet metal, explains that the stainless shafts he fabricates in relatively small lots are investment-cast rather than cut from barstock or formed by sand casting and then finished.

&#;For one thing, in this part of the country it is becoming difficult to find qualified machinists,&#; Mr. Johnson says. &#;There are few machinists or CNC operators coming out of schools today, and that&#;as well as the cost of equipment and labor&#;has become a problem for many machine shops. To an extent, investment casting alleviates this problem, because it eliminates some of the burden of machining.&#;

Want more information on stainless steel investment casting parts? Feel free to contact us.

Additional reading:
Everything You Need to Know About Sluice Valve

Several years ago, Staten Island Machine Shop began having some of the parts they previously had sand cast instead supplied by Rimer Enterprises, an investment casting specialist.

Mr. Johnson adds that the stainless steel gears his shop now gets from Rimer, typically for marine applications, are high-precision parts that slide over or under other components. In the past, when the gears were made from sand castings, there could be significant shifting or other movement.

&#;This problem is far less likely to happen with investment-cast gears because the rotations are right on, the holes are exactly where they should be, and all critical dimensions and tolerances are very close, which also minimizes the need for machining,&#; he says.

While reducing the demand on machine time is a significant savings, there is also substantial added savings in costly metals used to fabricate many parts. Chuck Myers, president of Rimer Enterprises says, depending on the metals and alloys used to make the castings, the differences in material costs could be stunning.

&#;For example, if you are machining a piece of stainless steel that costs $5 per pound, you might be machining 80 percent of the steel out for your finished product,&#; Mr. Myers explains. &#;By the time the part is finished you&#;ve got 4 pounds of stainless steel chips that you end up selling to a scrap dealer for $2 per pound. If the same part is investment-cast, the near-net shape eliminates the scrap, which could represent many dollars in savings per part in alloy cost as well as labor.&#;

The general manager of an Ohio-based machine shop says that one of the main reasons he buys investment castings is that he can&#;t get the needed material in barstock and prefers not to use sand castings. However, the savings on materials is also significant.

&#;The advantage of getting a near-net shape means less machining and also material savings,&#; the general manager explains. &#;So when you make parts with alloys, such as the nickel-based alloys that we use, there is a significant cost savings because you don&#;t have to throw half of the metal away in chips. And of course, the machine time is less when you have parts that are cast close to size.&#;

This shop, which also has its investment castings made by Rimer, recognizes that the consistency of investment-cast products is a noteworthy benefit.
While investment casting may provide quantum savings in terms of time, material and labor, some people have concerns about turnaround time. &#;When we need castings it is usually because a customer is running the same part except that the dimension may change,&#; the general manager says. &#;We try to stay ahead of the game, but we can&#;t anticipate how long their production runs are going to be. So, if we get caught short, any delay in turnaround time can really hurt.&#;

In anticipation of such problems, Rimer made substantial new investments in its in-house capabilities when it took over ownership of the business several years ago. For example, in , it installed a robot dipping system to reduce leadtime through the shop and improve the consistency of products. The newly expanded facilities also include a very modern CNC tooling shop and a CNC machine shop for machining castings.  

&#;Turnaround time in our industry is often 10 to 12 weeks,&#; Mr. Myers says. &#;We have been able to cut that time more than 60 percent. In emergency situations, we will do everything we can to turn around the needed castings as quickly as possible.&#; 

 

 

 

If you are looking for more details, kindly visit stainless steel lost wax cast.