Investment casting
Investment casting, also called lost-wax casting, is a process in which a wax model of the part is coated with ceramic, melted out, and the resulting shell is filled with molten metal. It produces complex, near-net-shape parts with fine detail and smooth surfaces, mainly in carbon, alloy and stainless steel.
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Typical parts
- Levers, forks and linkage parts
- Pump impellers and valve components
- Brackets and housings with complex shapes
- Parts for food processing and packaging machines
- Hardware and fittings in stainless steel
Quantities
- Quantities that pay for the wax tool
Inspection
- Chemical analysis of each heat
- Mechanical properties on test bars or parts
- Full first article
- PT, MT or RT to specification
Documents
- EN 10204 3.1 certificate
- Dimensional report
How investment casting works
Wax models of the part are injected in a metal tool and assembled on a wax tree. The tree is dipped repeatedly in ceramic slurry and sand until a shell forms. The wax is melted out, the shell is fired, and molten metal is poured into the hot shell. After cooling, the shell is broken off and the parts are cut from the tree and finished.
Because the mould has no parting line and no draft is needed, investment castings can have undercuts, thin walls and fine detail.
Quality checks and documents for investment castings
Each heat is checked for chemical composition. Mechanical properties are tested on test bars or on parts, after heat treatment where specified. First articles are measured in full. Depending on the specification, castings are tested by penetrant (PT), magnetic particle (MT) or radiographic (RT) testing.
Standard documents are a material certificate to EN 10204 3.1 and a dimensional report. More on the quality page.
Materials for investment casting
Carbon and low-alloy steel
- GP240GH (1.0619, formerly GS-C25)
- G20Mn5 (1.6220)
- G42CrMo4 (1.7231)
Stainless steel
- 1.4308 (CF8)
- 1.4408 (CF8M)
- 1.4581
Precipitation-hardening stainless
- 1.4542 (17-4PH, ASTM A747 CB7Cu-1)
Aluminium
- EN AC-AlSi7Mg0.3
There is no fixed size or weight limit. Send us your drawing and we will define the right production route for the part and confirm feasibility. Investment casting tolerances are tighter than sand casting tolerances and are agreed on the drawing, usually with reference to ISO 8062-3.
Is this the right process?
When investment casting is the right choice
- The part is small to medium sized with a complex shape
- The material is steel or stainless steel
- Machining from solid would take long or waste a lot of material
- Several machined or welded parts can be combined into one casting
When another process is better
- Large or heavy parts: sand casting is more economical
- Simple shapes with high fatigue loads: forging gives better grain flow and strength
- Aluminium parts in high volumes: die casting has shorter cycle times
- Simple geometry in small quantities: CNC machining from bar avoids tooling cost
Related pages
- CNC machiningCNC turned, milled and ground parts, EDM, laser and waterjet cut parts from machine shops in Türkiye, from prototypes to series, with dimensional reports.
- Secondary operationsHeat treatment, galvanising, powder coating, KTL e-coating, painting and assembly for cast, forged and machined parts, managed by QProcess in the same order.
- Machinery and equipmentMachine bases, housings, shafts, gear blanks, guides and plastic wear parts for machinery and equipment manufacturers, produced by manufacturers in Türkiye.
- Agricultural machineryGearbox housings, PTO shafts, hubs, brackets, counterweights and wear parts for agricultural machinery manufacturers, produced by manufacturers in Türkiye.
- Other industriesCast, forged, machined and plastic parts for pumps and valves, hydraulics, rail, material handling, industrial automation, robotics and marine equipment.
- AerospaceMachined, investment cast and plastic parts for aerospace projects, produced in Türkiye by manufacturers that hold the certification the sector requires.
- MedicalMachined stainless steel, aluminium and plastic parts for medical equipment, from manufacturers in Türkiye that hold the certification the sector requires.
Frequently asked questions
When is investment casting cheaper than machining from solid?
When the part has a complex shape that would take long machining time or create a lot of chips, and the quantity is high enough to pay for the wax injection tool. Levers, brackets and impellers are typical examples. We compare both routes when we quote.
Which steels can be investment cast?
Most carbon, low-alloy and stainless steels can be investment cast, including grades such as 1.4308, 1.4408 and 17-4PH (1.4542). Duplex stainless steels and tool steels are possible with suitable foundries. Aluminium can be investment cast as well.
How smooth is the surface of an investment casting?
Investment castings have a smoother surface than sand castings, and many surfaces can stay as cast. We do not state a fixed roughness value: send us your drawing with the surface requirements and we will confirm with the foundry which surfaces can stay as cast and which need machining.
Send your drawing. You get a quotation in 3 to 5 working days.
Your drawings are handled confidentially; NDA on request.