Sawing and machining must be done wet. Because this material is porous and will corrode, an oil-based coolant should be used wherever possible.

Finish machining should be carried out at a slower rate than with other mould steels due to a tendency to chip or splinter as the tool exits the work piece. “Picture framing” or machining the parameter of the insert first will help avoid these potential problems.

Welding is not recommended. It is preferable to re-machine the Porcerax insert and then weld or shim in the core pocket. Silver soldering or brazing may be carried out but obviously the material will lose its porosity in the area affected.

Porosity will be greatly reduced during machining as the pores are “smeared” closed. After machining, the porosity must be re-established by EDM or polishing.

Polymers must be matched with the appropriate grade of Porcerax (7µm or 20µm pores). Nylon, for instance, will flow into 20µm pores while polypropylene and ABS will not.

Texturing is possible but requires special measures. Contact Carrs Toolsteel Technologies for detailed information.

Mould release agents such as silicone sprays will clog the pores if sprayed onto the surface. Positive air pressure should be blown back through the exhaust line while the mould is being sprayed.

Exhaust holes should be adequate in number and properly placed to ensure optimum venting. They should ideally be equipped with the facility for a high pressure back flush which will be of great assistance in maintaining porosity (Note that this blow back operation can also be used to assist the release of the moulding without ejector marks).

Venting is dependent on the surface area of Porcerax, its thickness in relation to the volume of the mould cavity and its cleanliness. Aim to provide the maximum possible venting area to allow fully effective venting even when some porosity is lost before cleaning becomes necessary. One or more exhaust holes through the core block must be adjacent to an EDM or polished area on the side or back of the Porcerax insert. The cavity side must also be EDM or polished to ensure full porosity.

Cleaning must be carried out before Porcerax goes into production to remove EDM and cutting fluids, and periodically during production to remove any build-up. Because of Health & Safety and fire risk, it is recommended that Porcerax should be professionally cleaned with acetone in an ultrasonic cleaner designed for use with flammable solvents in conjunction with a 10BAR acetone flush. This is the only satisfactory method of cleaning and maintaining porosity.

Further technical information, recommendations and additional case studies may be obtained by contacting Carrs Toolsteel Technologies.