The Cordis process has meanwhile been available to the foundry binder market for more than 10 years. The process is based on an inorganic binder (silicat, phosphat and borat) one of the most environmentally compatible, low odor and smoke binders in existence. Curing of the core in the corebox takes place by means of water removal.

At present, this binder is a favorite in aluminum foundries because of its excellent collapse properties after the casting operation.

Cordis is an inorganic binder (silicat, phosphat and borat). Curing of the core in the corebox takes place by means of water removal. The molding sand produced using this one-component system may also be cured with the aid of conventional ester-based hardeners.

The molding sand mix, made with H33 (AFS 55) silica sand, can be prepared in any commercial mixer. Depending on the geometry of the cores to be fabricated, the addition level of Cordis to sand is 2.0 ? 2.5 Parts by Weight (PBW). The sand mix is ready for use as soon as it leave the mixer. The molding sand mix is very easy to process.

If the mix is kept in a sealed container, one that excludes air, it can still be processed after days of storage. Under normal working conditions, daily cleaning of the core shooter is unavoidable.

	Figure 1

The coreboxes used for this process must be modified in such a manner that a large flow of warm air can be quickly and directly passed through the corebox. The corebox should be constructed of a material that can be heated to approx. 200 °C.

Since - as previously mentioned - curing is critically influenced by the throughput of warm air, it is important to keep the temperature of the required air at 150 °C over the entire gassing period. The achieved gassing time for an intake manifold core would be 30 seconds.

Figure 1 shows a core for the rear suspension of a motorcycle. The core weight is 3.8 kg, and the curing/gassing time is 110 seconds.

The cores should be stored in a room where the relative humidity does not exceed 50 %.

Thanks to the inorganic nature of the binder, no residues in the form of condensates form during the casting operation. This ensures increased productivity, since the permanent molds need not be cleaned several times per shift as is otherwise necessary. The lack of condensate also implies another benefit, namely the reduced odor. In an emission test, Cordis-bonded cores were heated to 650 °C in an oven and the liberated gasses collected in a water trap. The water was then analyzed. The results are listed in the following table.

Advantages

• Environmentally friendly
• No odor during core fabrication or the casting operation
• No smoking during the casting operation
• No resin residues on the permanent molds
• No ventilation system necessary Mechanical de-coring possible
• One-omponent binder system

Disadvantages

• Binder shelf life three months
• Humidity/moisture reduce the storage life of the cores
• Sand crusting on the submerged nozzles

To ensure an optimized product selection according to your needs; please contact your nearest HA-Representative.