Investacast Ltd - Precision Castings

Mullacott Cross Trading Estate,
Ilfracombe, North Devon,
EX34 8PL, UK

Tel: (+44) (0)1271 866 200
Fax: (+44) (0)1271 867 148

E-Mail: info@investacast.com

Process

Casting Design

Our technical team will liaise with your design engineers to finalise the best possible design to suit the casting process.

Drawings can be received as hard copy or electronic format, (Surface[IGES]/3D Solids or 2D[/DXF]. We will if required produce a CAD casting drawing from existing components/samples.

For simple rules of designing for casting please see simple design rules

Tooling

A pattern die is designed and manufactured using CAD/CAM techniques. Investacasts skilled toolroom personnel manufacture dies using precision CNC machining/EDM techniques. Investment tools are constructed primarily of Aluminium with cores/ retractable slides produced in Brass or Steel.

As no draft is required for the process of wax pattern production parrallel sided Chassis/Boxes can be produced with ease. Reverse form features/undercuts and complex internal 3D forms can be produced by "Collapsing" the cored feature or by using "Soluble" wax inserts.

Wax Pattern Injection

Liquid pattern wax is injected under temperature/pressure controlled conditions to ensure dimensional consistency from the first to the one hundred and first injection cycle. After solidification the wax pattern is ejected freely from the die.

Automatic or Manual tooling can be produced dependant on the production requirements. Tool life is extremely high due to the low temperatures/pressures and low abrasive nature of the waxes used.

Pattern Assembly

Wax patterns are then assembled onto a wax runner system which provides access for the molten metal.

With over 30 standard designs of "Runners" (Trees/Assemblies/Frames), castings of all sizes and sections [from postage stamp to pedal bin size] can be produced to a high level of soundness.

Mould Making

After the completed wax assemblies are produced and cleaned, a ceramic shell is produced by repeatedly dipping the wax assembly first in a liquid ceramic slurry followed by coating with ceramic stucco.

A fully automatic "Shellmaking" robotic system is employed to invest the assemblies. A number of coats are applied until the "Investment Shell" is thick enough to withstand the thermal stresses of pouring.

De-Waxing

The complete mould is then placed into a steam pressure vessel and the wax steamed out to leave the negative hollow cavities of the components inside the "Investment Shell".

Mould Firing

Ceramic Shell moulds are fired at 1000°C to remove residual traces of wax, enhance the mechanical strength of the shell and to preheat in preparation for the casting process.

Pouring

The specified alloy is melted in either an induction furnace or electric resistance furnace and gravity poured into the pre-fired investment mould. Cast mould weights of up to 35KGs are cast [steel/copper/nickel] and 10KGs [aluminium alloys].

Over 50 air melt steel alloys, several Nickel based and most common Copper base alloys are stocked on site at Investacast. Aluminium alloy castings are resistance melted, rotary Nitrogen degassed and gravity poured to achieve a high level of integrity.

Finishing

When the metal has solidified the ceramic mould is removed and cleaned off with pneumatic vibratory equipment. The castings are then cut off the runner, fettled and shot blasted ready for heat treatment or inspection.

Heat Treatment

Castings are heat-treated either to enhance mechanical properties, improve machinability or to homogenise as cast structures. Heat treatment is undertaken on site using atmosphere controlled furnaces.

Inspection

Finished castings are visually/dimensionally inspected and if required NDT is undertaked to verify integrity.

Namas approved laboratories are utilised for MPI / DPI / RADIOGRAPHY. On site facilities exist for Spectrographic analysis of alloys.

Post Cast Finishing Processes

Most customers prefer to purchase machined / painted / polished / plated parts. Investacast can offer many post cast finishes such as:-