The dummy block is a critical element of the aluminum extrusion production process. Its successful operation depends on a number of factors. For example, press alignment (both thermal and physical), lubrication, maintenance and so on. The most important factor in the effective operation of any dummy block is its efficient interaction with a round, straight, thermally and therefore dimensionally stable container.
- Allow gases to escape during the combined process of billet upset and burp decompression reducing blisters
- Maintain a minimal uniform skin of aluminum on the liner ID reducing profile inclusions
The function of the dummy block is the extension of the ram or stem, which pushes the softened alloy through the die.
There are a number of functions that must be satisfied by an effective dummy block.
- To repeatedly transmit the force of the ram, at high temperature, to the alloy.
- To expand quickly under load and maintain a secure seal with the container wall, leaving only a thin film of alloy on the liner.
- To separate cleanly from the billet at the end of the stroke.
- To contract immediately, and return through the container without stripping the film of alloy from the liner.
- To cause no gas entrapment that can result in blistering, or damage the face of the container and/or dummy block.
- To compensate for minor press misalignment.
- To be quickly and easily removed and replaced.
- To function effectively until a production run is complete.
Benefits of the Castool Dummy Block
- Reduce scrap, due to back end blisters and surface defects
- Reduce cost of operation
- Reduce downtime
- Increase productivity
- Increase operating life
With these dummy blocks, Castool again sets a new standard of excellence in the extrusion industry. Results may vary depending on individual press characteristics and setup.