grain size graph & discussion

1. Discussion
Grain size distribution is major determinant of mould and care green compression
strength, permeability and surface finish of the casting. From our experiment and graph
of Percentage of Sand Retained versus Aperture Sizes, we found that the aperture size
number that are optimum for the sand casting is 300 μm, 212μm and 150 μm whereby if
following the usual range is 150-400 μm. The percentage that from our experiment
showed that the preferable percentage of optimum sand that usually use for sand casting
is less than 10% instead of the Chelford 60’s experimented sand which the percentage is
more than 75%. Therefore our experimented sand sample is not suitable for sand casting
purpose as the majority of the percentage is more or about 850 μm. Furthermore, the
coarser the sand it is, the higher the permeability but the lower the green strength will be.
Therefore, the surface of final products will rough and surface will have metal
penetration. Therefore, we must carry out experiment before start the mixing and
producing of green sand. Based on the Percentage of Cumulative Sand versus aperture
Sizes graph that we obtain from the experiment, our sand sample is considered as well
graded even though our optimum sand size is less than the Chelford 60’s experiment.

2. Conclusion
From our experiment, we can draw a conclusion from the experiment of our sand sample
that the percentage of sand retained became finer as the aperture sizes decreases. Besides
that, the percentage of cumulative sand slightly increases as the aperture sizes decreases.
Furthermore, from our experiment, we can clearly see that our sand sample is not suitable
to use for the sand casting as only less than 15% of optimum requirement of sand is
collected after the experiment. Hence, our objective for this experiment is achived.

3. References
 Campbell, John (1993). Castings. Butterworth-Heinemann.
 Degarmo, Black & Kohser 2003, p. 300.
 Todd, Allen & Alting 1994, pp. 256–257.
 Metal Casting Techniques - Vacuum ("V") Process Molding, retrieved 2009-11-
09.
 The V-Process (PDF), retrieved 2009-11-09.
 ASM International (2008). Casting Design and Performance. ASM International.
p. 34.ISBN 978-0-87170-724-6.
 Sias, Fred R (2005). Lost-wax Casting: Old, New, and Inexpensive Methods.
 Brown, John R (1994). Foseco Foundryman's Handbook