Atlas of Wax Pattern Defects
There are occasions when internal details of a component are required to be cast around ceramic or soluble cores. It is necessary therefore to inject wax around the ceramic or soluble core during the wax injection process.
There are a variety of challenges associated with this type of process that may result in nonconforming wax patterns or damage to the ceramic or soluble core.
This section will follow the same format as the aforementioned, except the material will now be specific to the use of ceramic or soluble cores.
• Make sure that the ceramic core is properly prepared prior to injection.
• Where there are deeper design slots or holes, it is best to fill them with wax prior to injection. This will prevent sink/cavitation in these areas.
• To prevent the wax from lifting from the ceramic core, it may be an advantageous to coat the core with a substance that will promote adhesion.
• For fragile cores that have yield problems:
• Consideration should be given to X-raying cores prior to and after injection to ensure core integrity.
• Prior to injection, do a pre-clamping of the die with core installed. Open die and examine core. If no crack, then continue. If cracked, then check core dimension or the die to see which one is causing the problem.
• Make sure soluble cores are prepared properly prior to injection.
• Be sure to completely remove all soluble core pattern material to avoid potential casting inclusions or improperly formed core cavities in the casting.
• Soluble cores will “grow” in size and deteriorate in the presence of high humidity; it is recommended that soluble cores be used as soon as possible after production and stored, if necessary, in a humidity-controlled environment (sealed bag) until used.
• It is important to avoid cross contamination of waxes. To avoid pattern wax contamination with soluble wax, mixing and injection equipment used in interchangeable environments, the equipment that comes in contact must be thoroughly cleaned and flushed prior to completing the changeover. Recommend having dedicated equipment for pattern and soluble wax.