Investment casting foundry

High grade steel components by using investment casting

CIREX is one of the largest steel-casting companies in the world and produces complex castings with extreme precision using the “lost-wax” method. Thanks to this versatile method our engineers have considerable freedom in the product design and choice of materials. This means that in consultation with you we can produce optimum castings that meet your exact wishes and requirements.

Investment casting properties

CIREX produces precision castings using the lost-wax technique. These castings have low surface roughness values, precise tolerances and are the highest quality steel castings available on the market. They are often used for components that operate in hostile environments, such as large differences in temperature or where the components are required to be especially hard, strong or light. To meet these tough demands, special alloys are often used for these castings.

Properties

Shape tolerance:
Roughness:
Dimensional tolerances:
Materials:
Complexity:
Machining:
Undercuts:
Series:

Description

Freedom in style and design
High surface quality & low roughness values (Ra 1.6 – 6.3 µm)
High dimensional accuracy and precise tolerances (VDG P690 D1)
Virtually any steel alloy can be cast
Complex shapes can be cast as a single component
Little to no machining is required
Products with undercuts can be cast
Suitable for smaller and larger series

Process investment casting

How does ‘investment casting‘ (lost-wax) work? Click on “read more” for an overview of the steps and phases involved. CIREX is one of the largest lost-wax foundries in the world. Using this method, we produce high-quality investment castings of complex shapes with extreme precision. As this process offers considerable freedom in the casting design and material choice, we can produce the castings according to your specific requirements with maximum efficiency.

Investment casting process steps

Step 1: Mould engineering & production

CIREX is one of the largest lost wax foundries in the world. By means of the lost wax method, high quality investment castings are produced with complex shapes and high dimensional accuracy. Besides that, this process offers a great degree of freedom in design and material choice. Your specific wishes and demands can be incorporated into the castings. By our decades long experience with the lost wax method, we can assure you a very efficient production process and top quality castings.

Step 2: Wax model spraying & Tree building

The mould is filled with liquid wax. After the wax has been cooled down, ejectors in the mould push the wax model out. A wax model has now been sprayed which is identical to the final casting. These wax models are glued onto a so-called wax tree with a casting funnel on top, into which steel is poured in a later stage off the process.

Step 3: Rinsing the wax trees      

After the wax models have been glued onto a wax tree, they are rinsed. Any possible contaminations on the surface are removed to ensure a successful attachment of the ceramic onto the wax tree.

Step 4: Building ceramic layers

After rinsing the wax tree, the tree is given a fireproof ceramic shell. This shell is constructed after repeatedly submerging the tree (up to 7 or 9 times) in a slurry and sprinkle it with ceramic sand. The ceramic layers are then hardened in a drying chamber where they are exposed to air.

Step 5: Autoclave

After the layers have been formed and dried, the wax is melted out of the ceramic tree by using steam (120°C)  in an autoclave. This is why it is called “lost wax casting”. The majority of the molten wax can be regenerated and is reusable.

Step 6: Sintering

The ceramic tree is then baked (stoked) at high temperatures of around 1100°C and reaches its final strength through the sintering process. Any wax remains are burned out during this process.

Step 7: Casting

The desired steel alloy is melted in a large furnace of 800kg and brought to cast temperatures. The ceramic tree is, at the same time, heated in a oven to prevent thermal shocks during the pouring process.  After the tree has been heated, it is removed from the oven by a robotic arm and filled up with a steel alloy by use of counter gravity. When the trees have been poured, they are placed on a cooling conveyor where they are cooled down. (with nitrogen).

Stap 8: Finishing

The trees are then removed from their ceramic shell, by using a fully-automatic hammer to break the shell. This removes the majority of the ceramic. The next step is to cut the products from the trees by sawing or vibrating.  The steel leftovers will be sorted based on alloy and can be melted again during the next casting session.

Step 9: Blasting, grinding and visual inspection

The Finishing Department removes the last pieces of ceramic by means of steel, sand and/or water blasting. The ingate which remained after the sawing process, is grinded from the casting. To grind the product properly, a grinding fixture is often applied.
The Quality Department checks all products visually for possible casting failures. This check takes place according to a quality standard sheet to ensure that all possible surface failures are corrected properly. Due to this procedure you can be assured that CIREX only delivers high quality castings.

Step 10: Machining and heat- and surface treatment

CIREX has the capabilities to machine castings in house, such as drilling holes, tapping threads and turning & milling activities. This enables CIREX to deliver a completely machined component that is ready-to-install.

Some alloys require heattreatment to achieve a certain hardness, tensile strength or elongation according to 2D drawing specifications. The standard heattreatments are performed in-house, the complex treatments are outsourced. CIREX also has the know-how to perform a surface treatment for a casting.

Surface treatments involves the coating process of a steel surface, to enhance the looks of the surface or protect it against external influences such as corrosion (rust) and natural wear (damage).

Step 11: Final inspection

The final step in this process is another visual check and when necessary composing a measurement report and material analysis. After the final inspection, the products are ready for shipment to another satisfied CIREX customer.

Features & benefits

If you select CIREX to have your steel component developed and produced, then you are opting for quality, certainty and reliability. From idea to implementation. Our investment casting process has the following characteristics:

• Significant freedom of shape and design
• Nearly every steel alloy is possible
• High degree of dimensioning precision
• No release angle required
• High surface quality
• Obviates mechanical post-processing
• Non-releasing cores can be cast

Dimensions & tolerances investment casting products

Precise dimensioning characterises the lost-wax method. Extremely precise tolerances often make a design needlessly expensive. With our decades of knowledge and experience we can save you costs by determining the best dimensioning in consultation with you. The final result? Optimal use of our casting process.

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Surface quality investment castings

Materials

At CIREX, we always start with the product’s functionality. Once the functionality is clear, the product is developed further. An essential part of this is the choice of material. A good design depends entirely on the proper choice of material. It’s important to know the properties that the steel must possess. Consider, for example:

• Mechanical properties      (hardness, tensile strength, elongation and elasticity)
• Thermal properties            (heat resistance)
• Chemical properties          (acid resistance and the ability to withstand corrosion)

Metallurgical specialists at CIREX will be glad to help you choose the optimum alloy for your application. Also when it comes to choosing the right chemical composition, structure, hardness, tensile strength or heat resistance.