Problem Area |
Symptom |
Potential Problem |
Solution |
---|---|---|---|
Pattern Issues |
Softness in Patterns |
Moisture Absorption |
Dry pattern in a very low humidity environment |
Return to pattern supplier for replacement |
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Holes in Cracks in Pattern |
Damage to Pattern |
Return to pattern supplier for repair or replacement |
|
Patch with wax |
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Incomplete finishing |
Return to pattern supplier for repair or replacement |
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Leak Test Failure |
Surface holes or Cracks |
Find leaks and repair or return to pattern supplier for repair or replacement |
|
Has not proven to affect the performance of the pattern |
Overexposure to UV light |
Most likely will not affect performance of the pattern |
|
|
Solid areas in pattern |
Return pattern to pattern supplier for repair or replacement |
|
Shelling Problems |
Poor Shell Adhesion on QC Patterns |
Contaminants on pattern |
Wipe with etch solution or dip assembly in etch |
Poor Shell Adhesion on Runners, Gates or Sprues |
Contaminants on runners and sprues |
Wipe with etch solution or dip assembly in etch |
|
Autoclaving Problems |
Shell Cracks in Autoclave Cycle |
Vents not open to pattern interior |
Make sure all vents are open at the ends and where they attach to the pattern – pattern skin is punctured, prior to placing he shell in the autoclave |
Inadequate venting |
Increase number and size of vents. There should be at least one vent per pattern |
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Burnout Problems |
Incomplete combustion (material other than ash in the shell after burnout) |
Inadequate venting |
Increase number and size of vents. There should be at least one vent per pattern |
Inadequate oven temperature |
Increase furnace temperature to 1500F or higher |
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Inadequate burnout time |
Increase time in furnace to 2 hour for small patterns, 3 hours or longer for large patterns |
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Inadequate oxygen to support combustion |
Ensure that patterns are vented |
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Ensure that there is adequate oxygen in the furnace |
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Ensure that air can get into the shell easily |
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Casting Problems |
Inclusions in the casting |
Leakage of slurry into pattern |
Ensure patterns are properly sealed |
Hex pattern on castings |
Leakage of slurry into pattern |
Ensure patterns are properly sealed |
|
Surface Pitting |
Incomplete combustion of pattern |
Increase airflow through pattern |
|
Increase oxygen in furnace |
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Increase burnout temperature |
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Increase burnout time |
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Ash remaining in shells after combustion |
Rinse shell prior to burnout |
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Blow out shell hot if unable to cool for rinse |