Technical Review and Discussion:
Wet to Dry―Refractory Coating Control for Precision PUCB Sands S. Ramrattan, Western Michigan University, Kalamazoo, MI, USA
Reviewer: Silica is not usually considered to be a precision sand. Why was not Mullite or zircon used? These have been found to produce much more accurate and precise castings.
Author: For chemically bonded PUCB sand systems silica sand predominates. As such, the selection of sand system for this study was advised by the AFS Steering Committee.
Reviewer: Can you interpret the data presented in this paper that foundry personnel could use on the floor.
Author: As the industry moves to tighter dimensional con- trols of castings, stricter coating controls are required. Baumé as a singular refractory measures does not suffice. An out-of-spec Baumé measure does not suggest the correc- tive wet chemistry adjustment; in addition, coating solids, surface tension, and viscosity must be monitored to deter- mine the proper corrective action.
Reviewer: What are the specific concerns over the use of the Baumé test? Are these concerns documented in the previous literature?
Author: The results show that more stringent coating con- trol measures are needed. These concerns were previous- ly published by the AFS Mold Metal Interface Committee (Reference #6). There was high variability in Baumé data test-to-test and time-to-time. Also, the Baumé itself does not indicate the required coating adjustment required to bring a coating back into specification. Besides Baumé, coating solids, surface tension, and viscosity must be monitored to determine the proper corrective action when an out-of-spec Baumé is recorded.
Reviewer: What coatings were used in this investigation? What were the main refractory components of the coating?
Author: A generic graphitic based refractory coating was provided by participating industry sources as specified by the AFS 4F Steering Committee.
Reviewer: With what precision and accuracy does the mea- suring device determine the solids content?
Author: Two decimal places, measurement reflect an aver- age of three readings and standard deviations are provided.
Reviewer: Does this research define the optimum coating thickness?
Author: Additional studies would be required to determine the optimal coating thickness for this sand system.
22
International Journal of Metalcasting/Spring 11
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88