What is Investment Casting and how Does it Work

Factors To Consider When Choosing An Investment Casting Process

1. Materials Variation: Investment casting can be used for a wide range of materials, including steel, nickel, cobalt, titanium, and aluminum alloys (amongst many more). Different materials may require specific casting techniques or variations to achieve optimal results.
2. Complexity and Precision: Some investment casting processes are better suited for creating intricate or highly precise parts. For example, ceramic shell casting allows for finer details and smoother surface finishes compared to traditional plaster mould castings. All of our investment casting processes use highly specified ceramic shell materials to allow us to create incredibly small and intricate details while also being able to cast larger components (up to around 100 pounds).
3. Volume and Efficiency: Depending on the production volume required, different casting methods may be more efficient or cost-effective. For high-volume production, processes like shell moulding or continuous casting may be preferred due to their faster cycle times and higher throughput.
4. Part Size and Geometry: Certain casting methods are better suited for specific part sizes or geometries. For example, lost wax casting is versatile and can be used for a wide range of part sizes and shapes, while centrifugal casting is often used for cylindrical or tubular parts.
5. Surface Finish Requirements: Some industries or applications may have strict requirements for surface finish or dimensional accuracy. Different casting processes offer varying levels of control over these factors, allowing manufacturers to choose the most suitable method based on the application's needs.

The Benefits of Choice

We choose to offer customers multiple investment casting processes to deliver several key benefits to our customers:

• Flexibility
  Customers can choose the casting process that best suits their specific requirements, whether it's based on material, complexity, volume, or other factors. This flexibility ensures that unique needs are met effectively.
• Optimised Performance
  Different casting processes offer distinct advantages in terms of surface finish, dimensional accuracy, strength, or other performance metrics. By offering multiple options, our customers can select the process that optimises the performance of their parts.
• Cost-Effectiveness
  Certain casting processes may be more cost-effective for particular applications or production volumes. By having a range of options available, our customers are able to choose the process that offers the best balance of cost and performance.
• Innovation and Customisation
  Offering a variety of casting processes encourages innovation and customisation. Customers can explore new design possibilities, experiment with different materials, or develop unique solutions tailored to their specific needs.

Air Melt

Air melt casting is the most economical choice when the part geometry or alloy do not require the use of vacuum melting and casting. Our air melt offerings are listed below.

Tilt Pouring

Tilt pouring consists of melting the alloy in an induction furnace. When the alloy is ready to pour, the entire melting furnace tilts over to cast the metal directly from the melting pot. This minimises metallurgical impurities by minimising hold time and contact with atmosphere, but at the cost of efficiency as you need to melt smaller quantities of metal and cannot melt and pour at the same time. This can be used for steel, nickel, or cobalt alloys.

Ladle Pouring

Ladle pouring is similar to tilt pouring but instead of being poured directly from the induction furnace to the ceramic moulds, there is an intermediate step where the alloy is cast in to a ladle (essentially a large refractory pot). This can be more efficient for high volume components without strict metallurgical constraints. This can be used for steel, nickel, cobalt, or aluminium alloys.

Low Pressure Aluminium Casting

Low pressure casting is for aluminium alloys only. Alloy is heated by a steady state furnace and a mould is fixtured over top of the molten alloy. A slight vacuum then creates a low pressure area in the chamber with the shell, drawing the aluminium upwards in to the mould. This can be very good at minimising dross formation during filling and helping to fill fine details, but at the cost of throughput.

Roll Over Pouring

Roll over pouring is almost identical to tilt pouring, but instead of tilting the furnace and pouring the alloy in to an upright, stationary mould, the mould is fixtured to the top of the induction furnace and the entire furnace rotated upside down casting the entire subheat of molten alloy in to the mould all at once. This can be a good way of filling fine details but at the cost of efficiency with respect to regular tilt pouring. This can be used for steel, nickel, and cobalt alloys.

Vacuum Melt

Vacuum melt investment casting involves melting reactive alloys in a vacuum environment to prevent oxidation, ensuring precise and high-quality castings for complex designs. Our vacuum melt offerings are listed below.

Single Chamber Vacuum Casting

Single chamber vacuum pouring consists of placing a crucible with preloaded alloy on top of a preheated ceramic mould, loading both in to the vacuum chamber, pulling a vacuum, and then melting alloy which will eventually drop in to the mould. This is the most cost effective vacuum melting method for low to medium volume jobs but will struggle to meet needs as volume increases or parts require thin sections that will be difficult to fill. Can be used for steel, nickel, or cobalt vacuum cast alloys.

Double Chamber Vacuum Casting

Double chamber vacuum pouring has two separate vacuum chambers. One for the ceramic mould and one for the melting pot. While alloy is melting in the top chamber (under vacuum), the fired mould can be brought in to the bottom chamber and brought to vacuum. Once brought to vacuum, the two mould and melting chambers open and the mould is lifted in to the melting chamber. Molten alloy is then tilt poured from the melting pot in to the mould and allowed to cool under vacuum.

Our double chamber melting is highly automated to handle the highest volume jobs. It also is helpful for filling parts with fine details. But lower volume parts without the need for fine detail may be more economical to produce with single chamber melting. This method can be used for steel, nickel, or cobalt vacuum cast alloys.

Vacuum Centrifugal Casting

Centrifugal casting is similar to single chamber pouring but instead of alloy falling in to the mould once melted it is actually melted in a pot sitting beside the ceramic mould with connected channels for material flow. Once alloy is melted (under vacuum), the melting pot and mould begin to rotate at incredibly fast speeds. the centrifugal force created by this rotation pulls the metal from the melting pot in to the mould via the connecting channels.

This allows for castings with extremely fine details to be produced. It is also ideal for very expensive alloys because very little additional metal is needed to cast the part, saving waste produced by the gating and sprue material required in more traditional casting processes. Suitable for vacuum melt steel, nickel and cobalt alloys but used mostly for titanium castings.