LOST WAX CASTING – INVESTMENT CASTING : KEY INFORMATION

Investment casting, also known as Lost Wax casting, gives a wider freedom of design than most other metal forming techniques.

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MATERIALS

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

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.

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SIZE RANGE

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.

SURFACE FINISH

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.

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Casting specific features

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.

Our machining and surface treatment capabilities allow us to produce components with even finer surface finishes should they be required.

WALL SECTIONS

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.

Undercut Features

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 cores can be used to achieve the accurate production of complex internal details through the lost wax casting process.

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TOOLING

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.

QUALITY, TESTING & CERTIFICATION

Quality investment castings demand strict production procedures, rigorous quality control and the best inspection facilities all of which can be found at PI Castings. These are supported by a wealth of experience in the production of investment cast components. The established policy of PI Castings is to provide products of consistently high quality, fit for their intended purpose and delivered in conformance with the agreed specifications.

The company participates in national development work on investment casting techniques and materials and will continue to invest in new equipment and to employ the latest production methods and Quality Assurance philosophies.

As you would expect from a leading manufacturer of investment castings, at PI Castings we have in-house facilities for tensile testing, bend tests, Izod & Charpy impact tests (including sub-zero), hardness, chemical analysis (Spectrographic), 3D co-ordinate measuring, X-Ray (3 sets), dye-penetrant and magnetic flaw detection.

Our team at PI Castings has the experience and flexibility to meet the most stringent technical, quality and delivery requirements, which has enabled us to be approved to BS EN ISO 9001:2008 (including aerospace certification AS9100 rev. C), by NADCAP and other international organisations. The quality of our investment castings has led to us also achieving preferred supplier status with many major aerospace, defence, electronics, medical, oil industry and engineering companies in the UK and overseas. You can find out more information about our production standards and our quality promise on our quality page.

Get in touch

If you have any questions about our Investment Casting services, Machining services, Rapid Prototyping services or Low Cost Sourcing services, please make contact with one of our capable engineers and they will provide you with more information

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