Investment Castings of Stainless Steel, Cast Steel & Cast Iron

Investment casting, which is also known lost wax casting or precision casting, refers to the formation of ceramic around the wax patterns to create a multi or single part mold to receive molten metal. This process utilizes an expendable injection molded wax pattern process to achieve complex forms with exceptional surface qualities. To create a mold, a wax pattern, or cluster of patterns, is dipped into ceramic material several times to build a thick shell. De-wax process is then followed by the shell dry process. The wax-less ceramic shell is then produced. Molten metal is then poured into the ceramic shell cavities or cluster, and once solid and cooled, the ceramic shell is broken off to reveal the final cast metal object. Investment castings can achieve exceptional accuracy for both small and large castings in a wide range of materials.

Investment casting derives its name from the fact that the pattern is invested, or surrounded, with a refractory material. The wax patterns require extreme care for they are not strong enough to withstand forces encountered during the mold making. One advantage of investment casting is that the wax can be reused.

Lost Wax Investment Casting Process

Investment Casting Capacities and Raw Materials

The metals which can be used for investment castings include grey iron, ductile iron, low carbon steel, medium carbon steel, alloy steel, stainless steel, nickel based alloys, cobalt based alloys, aluminium alloys and other metal or their alloys. RMC's investment casting foundry is capable of meeting a wide variety of alloys material specifications according to ASTM, SAE, AISI, ACI, DIN, EN, ISO, GOST and GB. We have more than 100 different ferrous and non-ferrous alloys with which we cast parts using complex design structure. Due to the complex structure in dimension and geometric, the investment castings are produced to net shape or near net shape, minimizing the need for secondary processes such as lathing, turning or other machining process.

Lost wax investment casting can reach dimensional tolerance grade CT 5-7 according to ISO 8062. Our fully organized equipment and automation process controls allow for consistent and repeatable tolerances as close as ±0.1 mm. The lost wax castings can also be produced in a wide size range, they may be as small as 10 mm long x 10 mm wide x 10 mm high and weigh as little as 0.01 kg, or as big as 1000 mm in length and weigh as much as 100 kg.

Lost wax casting processed can produce steel casting parts with good surface quality, less surface defects, high accuracy in dimensions, small but complex structure with thin wall thickness. However, the cost per unit piece of investment casting would be comparatively higher than sand casting, lost foam casting and vacuum casting processes. Generally speaking, the lost wax investment casting with water glass as shell bond is about 1.2-1.7 times of sand casting, and the lost wax casting with silica sol as shell bond is about 1.5-2.5 times of water glass castings, by weight per kilograms, depending on the structure and size of the desired casting parts.

▶ Lost Wax Investment Casting Metals

• Carbon Steel: Low Carbon Steel, Medium Carbon Steel and High Carbon Steel, AISI 1020  - AISI 1060,
• Alloy Steel: ZG20SiMn, ZG30SiMn, ZG30CrMo, ZG35CrMo, ZG35SiMn, ZG35CrMnSi, ZG40Mn, ZG40Cr, ZG42Cr, ZG42CrMo...etc on request.
• Stainless Steel: CF8M, CF8, 1.4408, 1.4308, AISI 304, AISI 304L, AISI 316, AISI 316L, duplex stainless steel, super duplex stainless steel and other stainless steel gradeS.
• Nickel Base Alloys, Cobalt Base Alloys
• Brass & Copper.
• Grey Cast Iron, Ductile Cast Iron, Aluminium alloy and other Materials and Standards on request

▶ Capabilities of Investment Casting at RMC Foundry  

• Max Size per Casting: 1,000 mm × 800 mm × 500 mm
• Weight Range: 0.01 kg - 100 kg
• Annual Capacity: 2,000 tons
• Binder Materials: Silica Sol, Water Glass or their mixtures
• Casting Tolerances: CT4 ~ CT8 or On Request according to ISO 8062.

▶ Advantages of Investment Casting (Lost Wax Process)  

• Excellent and smooth surface finish of raw castings
• Tight dimensional and geometrical tolerances
• Complex and intricate shapes with high design flexibility and casting feasibility
• Capability to cast thin-walled castings therefore a lighter casting part
• Wide range of cast metals and alloys (ferrous, non-ferrous)
• No draft is required in the molds design
• Less or no need for CNC machining
• Less machining allowance than other casting processes

RMC Foundry is a leading precision casting factory in China of top-quality investment castings committed to delivering excellent quality, superior value and exceptional customer experience. RMC has the experience, technical expertise and quality assurance processes to consistently and reliably deliver an extensive range of precision castings with further processing.

Wax Replicas for Investment Casting

Wax Patterns

Molten Metal Pouring

Applications of Precision Investment Castings

Components made by investment casting are utilized to cast a wide variety of items, including high quality, high performance industrial parts of complex structures.

The application of the precision investment casting (lost wax casting process) components covers a wide range of industries, in our foundry they are typically used in the following areas (including but not limited to):

• Gearbox
• Agricultural Machinery
• Industrial Valves
• Pumps
• Rail Trains
• Ship Building
• Flow Meters
• Other Industries

Why You Choose RMC for Investment Castings

There are several reasons to choose RMC's foundry as your source for investment castings, including:

1.   • Engineering team whose members are focusing on metal casting field.
2.   • Extensive experience with investment castings of complex geometries
3.   • A broad range of materials, including ferrous and non-ferrous alloys
4.   • In-house CNC machining capabilities
5.   • One-stop solutions for investment castings and secondary process
6.   • Consistent quality guaranteed and continuous improvement.
7.   • Teamwork including toolmakers, engineers, foundryman, machinist and production technicians.

RMC's foundry has more than 20 years of experience in precision investment casting. Request a quote today on investment castings for your precision parts, or contact us for more information.

Stainless Steel Castings