NUST Institutions Library Catalogue

Sand Casting is very old technique for casting metal parts. In this process a pattern is
made which is a replica of the desired part. The pattern is placed in a box and curing sand is
poured around it. After curing of sand, pattern is detached so that replica is imprinted in the
sand. Then metal in molten form is added into the hollow portion and desired part is obtained
after cooling. The process is cheap and incorporates all kinds of metals, however, the
correctness of the final part is primarily dependent on the correctness of the pattern itself.
Rapid Prototyping (RP) is a collection of contemporary manufacturing methods which
create the part straight from Computer Aided Design (CAD) model using layer-by-layer
deposition technique. The CAD model is first sliced and each cross section of the CAD
model is used as a guide to deposit material at the desired location. The RP process varies
with the technology being used. Additive Manufacturing (AM) has been of significance
importance because of its precision and overall time reduction in product development
process. Moreover, a prototype can be developed to know the functioning of the actual part
which gives flexibility to designers to vary the design to eliminate the inaccuracies.
A case study was undertaken in this research work in collaboration with KSB Pumps
Hassan Abdal, Pakistan. KSB pumps are a well renowned manufacturers of pumps for variety
of applications. The company was facing problem in one of their pumps named ‘Sewatec
250-401’ whose performance (efficiency) was not up to the desired standards. The impeller
of the pump was being manufactured through manual pattern making and sand casting
techniques. After detailed study of the manufacturing process of the said pump, it was
observed that the vane of said impeller was manufactured in a crude way leading to doubts in
its accuracy. Therefore, it was decided that the vane of this pump will be manufactured
replacing existing manual pattern making with RP patterns and performance of the new and
old pumps will be compared.
The pump manufactured using RP technique showed higher efficiency (83.6%
efficiency) as compared to the one manufactured using manual patterns (74% efficiency) and
met all performance standards (82% efficiency). The manufacturing through RP reduced the
overall cost of the manufacturing by 1/8th and considerably reduced the time to manufacture
(by 11 weeks).