Additives

Uncoated castings

In the area of cold box production, uncoated casting provides an opportunity both to increase productivity and to ensure high-quality casting. Uncoated casting refers in particular to the use of a system for improving the casting surface which consists of additives and the appropriate binders and makes it possible to forego the coating process.
For the caster, uncoated casting opens up the possibility of saving material costs both for charge materials and for the peripheral equipment (furnace drying systems, coating pans, etc.). The most important point in favor of uncoated casting is arguably the fact that one or even two work steps can be saved. Both the coating process itself and the following drying take up time and involve personnel. For this reason, it can be expected that the omission of these work steps will yield an increase in productivity. Foregoing the coating process is also accompanied by a reduction of energy costs since the cost-intensive furnace drying of coated cores is omitted. In addition, alcohol-based coatings represent a particular potential danger in foundries from the point of view of occupational safety laws. Not using these materials means increasing safety at the same time.
Although coatings make a considerable contribution to good casting quality, they also constitute a possible source of error in the process chain, which must be factored in in the case of problems in production and their solutions. This source of error can be eliminated by switching to uncoated casting. Coating-specific casting defects, such as scabbing or inclusions, could be prevented this way.

Advantages from the use of additives

  • No need for expensive special sands, such as chrome ore sand, sand of Swedish provenience, zirconium sand or chamotte sand; in some cases, these sands can be substituted
  • Inexpensive auxiliary material that counteracts veining and has proven itself again and again
  • Relatively low added amounts
  • Uncoated casting is also possible under certain conditions