Materials & Design
Below covers Investment Casting in more detail. Covering key information which could influence design and material choice.
Parts can be cast in our very wide range of investment casting materials, including Aluminium, Low Alloy steels, Carbon steels, Stainless steels, Nickel and Cobalt based alloys, Magnetic irons, Brass and Bronze and Zinc.
If you would like some more information about the materials from which we can produce castings, you can download our detailed material charts, including Chemical Analysis, Mechanical Properties and Applications for your reference.
Tolerances that can be produced through Investment Casting are generally ± 0.125mm per 25mm (± 0.005″ per inch) but can vary depending on material, size and configuration of the casting. For more detailed information, please refer to our Tolerance Chart.
The nature of the process ensures consistent repeatability will be achieved for each casting produced, even on non-toleranced casting dimensions.
Our in house engineers can provide you with more information about critical and functional dimensions and how to provide tolerances in such a way as to keep the Investment Casting process as economical as possible. They will share this information with you upon enquiry.
At Precision Investment Castings we can produce investment castings that range from less than 5mm to over 600mm in size. Our team will be able to provide you with more information about how whether we can meet your production requirements upon being contacted – although these are our general production capabilities we may be able to achieve greater sizes depending on the design of your component.
The investment casting process produces finer quality finish than most other casting processes. The finish that can be achieved from investment casting is 3.2 microns (N8, 125CLA).
Our machining and surface treatment capabilities allow us to produce components with even finer surface finishes should they be required.
HOLES & SLOTS
Holes and slots should be kept as short as possible in relation to diameter or width. Through investment casting square holes, ‘D’ holes and other odd-shaped holes are as easy to cast as round holes. Blind holes are however more difficult to cast than through holes – we will advise you on what can be cast at the enquiry stage, and how we can use our other services and capabilities to meet your requirements.
Unlike die-castings and plastic mouldings, it is not necessary to have a uniformly thin section all over with investment castings. In fact, it is often helpful to have some thicker sections to enable metal to be fed into the casting at those points. Good design will enable sound castings to be produced and may result in significant weight and cost savings.
The section thickness that can be cast depends on the investment casting material, the surface area and the complexity of the casting. For Aluminium and Zinc, the typical wall thickness is 2 to 3 mm, but 1.5 mm or less can be achieved on some features. Thicker walls are needed for castings in Steel or Copper based alloys, usually 3 mm or more, but a thickness of 2 mm or less can be cast over small areas.
Investment Castings are ideal for producing undercut detail. Where complex internal shapes are required, removable inserts in the tool are used. If this is not possible, then soluble wax cores or ceramic preformed cores can be used to achieve the accurate production of complex internal details.
Tooling costs are relatively low compared to those associated with other casting processes as Aluminium dies are used to produce the wax patterns used in the investment casting process. As there is very stress placed on the dies during the casting process the life of each die is excellent. Modifications are also relatively easy if design changes are required, due to the fact that Aluminium is a material that can be easily worked.