Filters for Investment Casting

Filters for Investment Casting

Filtration effectiveness largely depends upon the correct application of STELEX ZR filters. The filters are applied in physically demanding applications and need to be well supported with no possibility of metal bypassing the structure.

In investment casting applications it is very unusual for the filters to become blocked; when considering the size of filter required, the rate at which the mould needs to be filled is normally the major consideration. As a generalisation, cast weights of up to 6kg can be satisfied with a 50mm diameter filter, and then up to 12kg with a 70mm diameter filter.

The most common filter application technique is in the pouring cup. Ideally a pouring cup which is specifically designed and supplied to be used with a filter will be employed. This enables a “straight sided” filter to be positioned in the pouring cup at the appropriate time.

STELEX ZR ULTRA provides the casting producer with the ability to produce higher quality castings using filtration technology with a greater degree of confidence in the performance.

A combination of improved zirconia ceramic and filter framing technology is the basis for the introduction of Foseco’s new generation of STELEX ZR ULTRA filters.

STELEX ZR ULTRA filters have a lower mass; this facilitates the generation of a more consistently open structure. The frame and ceramic ensure that the filter has very low friability. STELEX ZR ULTRA provides all the benefits normally associated with steel filtration together with some important new advantages:

  • Reduced potential for metal flow related issues
    • more consistent capacity and flow rates of metal through the filter
  • Potential for enhanced casting cleanliness
    • the use of finer filters with molten steel and alloys where previously this had not been possible
    • greater filtration efficiency and a higher level of turbulence control
    • reduction in the possibility of metal bypassing the filter
    • very low friability reducing the potential of filter inclusions in the casting
  • Foundries can have greater confidence in the overall performance of steel filtration products than ever before

STELEX ZR ceramic foam filters are based on zirconia; and consequently they are ideally suited to the filtration of molten steel and alloys poured at very high temperature.

The application of STELEX ZR filters in the casting gating system, either in the pouring cup or casting tree, will prevent non-metallic materials reaching the mould cavity. This increases the casting cleanliness generating lower scrap levels, or subsequent repair work. The manufacturing time and costs for the castings can be reduced allowing for a leaner and more reliable supply chain.

STELEX ZR filters facilitate a calm and controlled mould fill. This reduces the formation of “re-oxidation” defects and improves the finish of the cast component.

SEDEX is a range of silicon carbide based ceramic foam filters suitable for use in aluminium, copper base and iron applications to provide a smooth laminar flow of molten metal and prevent the ingress of slag and non-metallic inclusions into the mould cavity. The maximum application temperature for SEDEX filters is 1500 °C.

"Prior to our relationship with Weaver Materiel, we were purchasing riser sleeves direct from the OEM. As a stocking distributor, Weaver typically is able to deliver same or next day. OEM lead times averaged three to four weeks. With Weaver, I've been able to reduce my working inventory by about 40%."

- JD Schmidt, QA Manager, Ohio Ferrous Foundry

“Ashland Foundry & Machine Works and Weatherly Casting are grateful for the partnership in our working relationship with Weaver Materials.  Weaver has helped us maintain pricing and avoid increases in a volatile market.  Weaver has always kept us in supply of material when markets dictated shortages/allocation status.  If Weaver was not in our vendor pool daily production ability would have been negatively impacted.  Weaver is also technically able to review our foundry processes and make suggestions to either achieve a cost savings or process improvement.  I am looking forward to a continued collaboration between the Weaver team and my locations.”
- Chrissy C