Effects of chromium powder mixed in electrical discharge machining of AISI D2 hardened steels
Nowadays, electrical discharge machining (EDM) is the non-conventional method that has been used extensively in machining hard material that is commonly used in mold and die industry but the limitations of EDM will cause lower productivity and poor surface quality. EDM becomes most apparent by using...
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| Format: | Thesis |
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2015
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| Online Access: | http://eprints.uthm.edu.my/7024/ http://eprints.uthm.edu.my/7024/1/MUHAMMAD_RIDZUAN_IDRIS.pdf |
| Summary: | Nowadays, electrical discharge machining (EDM) is the non-conventional
method that has been used extensively in machining hard material that is commonly
used in mold and die industry but the limitations of EDM will cause lower productivity
and poor surface quality. EDM becomes most apparent by using powder metallurgy
electrode together with chromium (Cr) powder suspension into the dielectric fluid which
has led to the increasing of productivity and good quality performance and
characteristics. Therefore, by combining of both EDM parameters and machining
conditions by incorporating with specific magnetic system plus integrated with existing
filter system, it is highly expected that the machining speed can be enhanced. However,
there are difficulties to determine the best combination of these machining parameters in
order to increase the material removal rate (MRR) and at the same time to reduce the
electrode wear rate (EWR) with the acceptable surface integrity. This research
emphasizes the studies of Cr powder mixed in EDM machining of AISI D2 hardened
steel using copper tungsten electrode which has been done successfully. Data were
analysed using design of three factors at a time consisted of peak current (Ip), pulse-on
(Pon) and powder concentration(C). Discussions were made on the responses such as
MRR, EWR, Surface Roughness (Ra), surface morphology, recast layer (RL) and
microhardness (MH) on the selected samples from the same machining conditions.
Results have proved that Ip was the most significant parameter which has influenced the
machining responses on Cr powder mixed EDM of AISI D2. It is also found that proper
powder concentration of 2gram/litre enhanced the machining efficiency particularly in
MRR. Furthermore, introduction of proper addition of Cr powder in the dielectric also
decreased Ra and RL thickness. The EWR increased as the peak current increased, but
inversely with pulse-on. In general, the possibility of EDM process for machining AISI
D2 tool steel by incorporating Cr powder mixed in the dielectric is acceptable and the
entire objectives were successfully proven. |
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