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. Precision investment castings can achieve exceptional accuracy for both small and large casting parts in a wide range of materials.
The Steps of Investment Casting Process:
During the investment casting process, a wax pattern is coated with a ceramic material, which, when hardened, adopts the internal geometry of the desired casting. In most cases, multiple parts are cast together for high efficiency by attaching individual wax patterns to a central wax stick called a sprue. The wax is melted out of the pattern – which is why it is also known as the lost wax process – and molten metal is poured into the cavity. When the metal solidifies, the ceramic mold is shaken off, leaving the near net shape of the desired casting, followed by finishing, testing and packaging.
What Are The Investment Castings Used For?
Investment castings are widely used in pumps and valves, automobile, trucks, hydraulics, forklift trucks and many other industries. Because of their exceptional casting tolerance and exellent finish, the lost wax castings are used more and more. Especially, the stainless steel investment castings play a vital important role in the shipbuilding and boats because they have strong anti-rust performance.
There are several reasons to choose RMC investment casting foundry as your source for investment castings, these include:
- Engineering centric with a metal casting focus
- Extensive experience with complex geometries and hard-to-manufacture parts
- A broad range of materials, including ferrous and non-ferrous alloys
- In-house CNC machining capabilities
- One-stop solutions for investment castings and secondary process
- Consistent quality guaranteed
- Teamwork including toolmakers, engineers, foundryman, machinist and production technicians.
As the copper-based alloys, brass and bronze can be formed into highly complex parts, making them ideal for the investment casting process. Constant cost fluctuations can make these materials very price sensitive, making waste very costly, especially when considering CNC machining and/or forging as a manufacturing process to produce your casting parts. Pure copper is not usually cast. Investment (lost wax) casting is a method of precision casting complex near-net-shape details using replication of wax patterns. Investment casting or lost wax is a metal forming process that typically uses a wax pattern surrounded by a ceramic shell to make a ceramic mold. When the shell dries, the wax is melted away, leaving only the mold. Then the casting component is formed by pouring molten metal into the ceramic mold.
Brass is an alloy composed of copper and zinc. Brass composed of copper and zinc is called ordinary brass. If it is a variety of alloys composed of more than two elements, it is called special brass. Brass is a copper alloy with zinc as the main element. As the zinc content increases, the strength and plasticity of the alloy increase significantly, but the mechanical properties will decrease significantly after exceeding 47%, so the zinc content of brass is less than 47%. In addition to zinc, cast brass often contains alloying elements such as silicon, manganese, aluminum, and lead.
Casting brass has higher mechanical properties than bronze, but the price is lower than bronze. Cast brass is often used for general purpose bearing bushes, bushings, gears and other wear-resistant parts and valves and other corrosion-resistant parts. Brass has strong wear resistance. Brass is often used to make valves, water pipes, connecting pipes for internal and external air conditioners, and radiators.
Materials for Investment Casting Process at RMC Foundry | |||
Category | China Grade | US Grade | Germany Grade |
Ferritic Stainless Steel | 1Cr17, 022Cr12, 10Cr17, | 430, 431, 446, CA-15, CA6N, CA6NM | 1.4000, 1.4005, 1.4008, 1.4016, GX22CrNi17, GX4CrNi13-4 |
Martensitic Stainless Steel | 1Cr13, 2Cr13, 3Cr13, 4Cr13, | 410, 420, 430, 440B, 440C | 1.4021, 1.4027, 1.4028, 1.4057, 1.4059, 1.4104, 1.4112, 1.4116, 1.4120, 1.4122, 1.4125 |
Austenitic stainless steel | 06Cr19Ni10, 022Cr19Ni10, 06Cr25Ni20, 022Cr17Ni12Mo2, 03Cr18Ni16Mo5 |
302, 303, 304, 304L, 316, 316L, 329, CF3, CF3M, CF8, CF8M, CN7M, CN3MN | 1.3960, 1.4301, 1.4305, 1.4306, 1.4308, 1.4313, 1.4321, 1.4401, 1.4403, 1.4404, 1.4405, 1.4406, 1.4408, 1.4409, 1.4435, 1.4436, 1.4539, 1.4550, 1.4552, 1.4581, 1.4582, 1.4584, |
Precipitation Hardening Stainless Steel | 05Cr15Ni5Cu4Nb, 05Cr17Ni4Cu4Nb | 630, 634, 17-4PH, 15-5PH, CB7Cu-1 | 1.4542 |
Duplex Stainless Steel | 022Cr22Ni5Mo3N, 022Cr25Ni6Mo2N | A 890 1C, A 890 1A, A 890 3A, A 890 4A, A 890 5A, A 995 1B, A 995 4A, A 995 5A, 2205, 2507 |
1.4460, 1.4462, 1.4468, 1.4469, 1.4517, 1.4770 |
High Mn Steel | ZGMn13-1, ZGMn13-3, ZGMn13-5 | B2, B3, B4 | 1.3802, 1.3966, 1.3301, 1.3302 |
Tool Steel | Cr12 | A5, H12, S5 | 1.2344, 1.3343, 1.4528, GXCrMo17, X210Cr13, GX162CrMoV12 |
Heat Resistant Steel | 20Cr25Ni20, 16Cr23Ni13, 45Cr14Ni14W2Mo |
309, 310, CK20, CH20, HK30 | 1.4826, 1.4828, 1.4855, 1.4865 |
Nickle-base Alloy | HASTELLY-C, HASTELLY-X, SUPPER22H, CW-2M, CW-6M, CW-12MW, CX-2MW, HX(66Ni-17Cr), MRE-2, NA-22H, NW-22, M30C, M-35-1, INCOLOY600, INCOLOY625 |
2.4815, 2.4879, 2.4680 | |
Aluminum Alloy |
ZL101, ZL102, ZL104 | ASTM A356, ASTM A413, ASTM A360 | G-AlSi7Mg, G-Al12 |
Copper Alloy | H96, H85, H65, HPb63-3, HPb59-1, QSn6.5-0.1, QSn7-0.2 |
C21000, C23000, C27000, C34500, C37710, C86500, C87600, C87400, C87800, C52100, C51100 | CuZn5, CuZn15, CuZn35, CuZn36Pb3, CuZn40Pb2, CuSn10P1, CuSn5ZnPb, CuSn5Zn5Pb5 |
Cobalt-base Alloy | UMC50, 670, Grade 31 | 2.4778 |
INVESTMENT CASTING TOLERANCES | |||
Inches | Millimeters | ||
Dimension | Tolerance | Dimension | Tolerance |
Up to 0.500 | ±.004" | Up to 12.0 | ± 0.10mm |
0.500 to 1.000” | ±.006" | 12.0 to 25.0 | ± 0.15mm |
1.000 to 1.500” | ±.008" | 25.0 to 37.0 | ± 0.20mm |
1.500 to 2.000” | ±.010" | 37.0 to 50.0 | ± 0.25mm |
2.000 to 2.500” | ±.012" | 50.0 to 62.0 | ± 0.30mm |
2.500 to 3.500” | ±.014" | 62.0 to 87.0 | ± 0.35mm |
3.500 to 5.000” | ±.017" | 87.0 to 125.0 | ± 0.40mm |
5.000 to 7.500” | ±.020" | 125.0 to190.0 | ± 0.50mm |
7.500 to 10.000” | ±.022" | 190.0 to 250.0 | ± 0.57mm |
10.000 to 12.500” | ±.025" | 250.0 to 312.0 | ± 0.60mm |
12.500 to 15.000 | ±.028" | 312.0 to 375.0 | ± 0.70mm |