Manufacturing processes for steel are constantly evolving to meet the needs of manufacturers and their customers.
For example, precision investment casting is a cost-effective process for creating metal parts that cannot be produced using other methods. Precision investment casting is also known as shell casting, permanent mold casting, or stainless casting.
It’s a type of casting process that uses heat to fill a reusable hollow mold with molten metal.
In contrast to other casting processes.
— such as sand or die casting
— there’s no need for tools or molds after the initial setup.
This article explains everything you need to know about precision investment casting and why it’s beneficial in your manufacturing process.
What is Precision Investment Casting?
Precision investment casting is a process used to produce metal parts that have complex geometries that are not easily manufactured through other casting methods.
The process uses a reusable mold or “pattern” that is typically made of graphite.
The pattern is placed into a specialized sand-like molding mixture called “investment” which is heated to create a hardened pattern.
The molten metal is poured into the hardened pattern, then the mold is removed to release the finished cast part. Precision investment casting is also known as shell casting, permanent mold casting, or casting.
It’s a type of casting process that uses heat to fill a reusable hollow mold with molten metal.
In contrast to other casting processes — such as sand or die casting — there’s no need for tools or molds after the initial setup.
This makes investment casting an ideal casting process for high-volume production.
Why Use Investment Casting?
Precision investment casting is an ideal solution for manufacturing parts that have complex geometries that can’t be achieved with other casting methods.
These types of parts usually have a high value and require a high level of accuracy.
The main advantages of investing in casting are the ability to create intricate geometries, low labor, high-quality parts, and a shorter lead time than other casting methods.
Precision investment casting is also one of the most cost-effective methods of creating metal parts.
How Precision Investment Casting Works
Precision investment casting is a system for making parts by filling a reusable pattern with molten metal.
The pattern is placed in a “skeleton” mold consisting of an investment material (a type of refractory ceramic that melts when heated).
The investment material is heated in a kiln to over 2000°F (1093°C), which causes it to melt, forming a hardened mold around the pattern.
When the mold cools, the molten metal is poured into the mold, completely filling the intricate geometry of the part, and then allowed to cool and solidify.
Once the part is completely cooled, the mold is removed, revealing the part.
What materials are used in stainless steel precision investment casting?
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The corrosion-resistant properties and healing ability of stainless steel are created by a chromium-oxide film that comprises at least 10% chromium.
These metals are highly-formable and allow for the production of precise dimensions, complex structures, and smooth surfaces.
What are the advantages of stainless steel precision investment casting?
stainless steel precision investment castings of various alloys can provide a wide variety of end-user benefits, including:
- Excellent corrosion resistance
- Resistance to heat
- Tolerances for precision
- Exceptional attention to detail
- Excellent surface finish
- Capability to create complex shapes
- Tolerance levels are extremely high.
- After casting, only minor surface finishing is required.
Precision investment casting applications industry
The precision investment casting process is highly versatile and can be used to create a wide range of parts.
Precision investment casting can be used for alloys like aluminum, copper, nickel, silver, iron, cobalt, gold, and many other alloys.
The precision investment casting process can be used to create parts with intricate geometries that would be difficult to manufacture using other casting methods.
Precision investment casting is often used to create complex medical devices, metal tools and equipment, automotive components, propellers, machine parts, and other metal products.
Two basic characteristics of stainless steel casting process
Since the shortening of stainless steel fine casting is much greater than that of cast iron, in order to avoid the defects of shrinkage and shrinkage in the casting, methods such as riser and cold iron and subsidies are mostly used in the casting process to achieve sequential condensation.
In order to avoid the defects of shrinkage cavities, shrinkage porosity, pores and cracks in stainless steel castings, the wall thickness should be uniform, sharp and right-angle structures should be avoided, sawdust should be added to the casting sand, coke should be added to the core, and hollow molds should be used.
Cores and oil sand cores, etc. to improve the concession and air permeability of sand or cores.
Due to the poor fluidity of molten steel, in order to avoid cold insulation and lack of pouring of steel castings, the wall thickness of steel castings should not be less than 8mm;
dry casting or hot casting should be used; the pouring temperature should be properly increased, generally 1520 ° ~ At 1600°C, due to the high pouring temperature, the superheat of molten steel is large, and the liquid remains for a long time, and the fluidity can be improved.
However, if the pouring temperature is too high, it will cause defects such as coarse grains, thermal cracking, pores, and sticky sand.
Therefore, for small, thin-walled, and complex-shaped fine castings, the pouring temperature is about the melting point temperature of steel + 150 °C; the structure of the pouring system is simple and the cross-sectional size is larger than that of cast iron; the pouring temperature of large and thick-walled castings It is about 100°C higher than its melting point.
Stainless Steel Casting Alloys
The most common alloys used in investment casting are stainless steel and high-nickel iron. These alloys are suited to investment casting because they are resistant to corrosion (so they last longer in the field).
Investment cast stainless steel is used for high-value products, like medical devices, that need to be corrosion-resistant. High-nickel iron is commonly used for intricate castings that are difficult to machine.
Castings made from this alloy are often used in automotive, HVAC, and other industrial applications.
Nickel-based alloys are also used for investment casting, but not as often.
You should choose nickel-based alloys based on the desired mechanical properties of your part.
3D Printed Molds in Precision Investment Casting
Investment casting can be used to create parts with complex geometries that can’t be manufactured using other casting methods.
To create the mold for the part, you can 3D print the mold using a CAD system.
Investment casting allows you to create intricate geometries that can’t be manufactured using other methods.
When 3D modeling the mold, take into account the shrinkage of the casting materials.
Pros of the Precision Investment Casting Process
– Complex geometries: Precision investment casting allows you to create complex geometries for your part that would be difficult to achieve with other casting methods.
– Low labor: The main advantage of investment casting is that there is low labor required to produce the part after the initial setup.
– High-quality parts: Investment casting produces high-quality parts with excellent mechanical properties.
– Shorter lead time: Investment casting has a shorter lead time than other casting methods.
– Cost-effective: Investment casting is one of the most cost
-Effective methods for creating metal parts.
Cons of the Precision Investment Casting Process
– Longer set-up time: The investment casting process has a longer set-up time than other casting methods.
– High capital investment: Investment casting requires a high capital investment compared to other casting methods.
– Geometry limitations: One disadvantage of investment casting is that the geometry of the part is limited by the geometry of the mold.
– High operating temperatures: The investment casting process requires high casting temperatures, so it must be done in a special facility.
Is Precision Investment Casting Right for You?
Precision investment casting is a great choice for manufacturers that produce high-value products with complex geometries where sand or die casting is difficult or uneconomical.
Precision investment casting is a reliable and repeatable process that creates parts with excellent mechanical properties.
The investment casting process is best suited for manufacturers who can benefit from high accuracy, low labor, and high-quality parts at an affordable price.
