Sustainable Research and Innovation Proceedingshttp://localhost/xmlui/handle/123456789/28142024-03-29T07:06:50Z2024-03-29T07:06:50ZEffect of Dielectric Fluid and Vibration on Performance in Electrical Discharge Machining of AlSiC Metal Matrix CompositesMwangi J. W.Ikua B. W.Nyakoe G. N.Zeidler HKabini S. Khttp://localhost/xmlui/handle/123456789/31872017-05-24T13:56:01Z2017-05-24T00:00:00ZEffect of Dielectric Fluid and Vibration on Performance in Electrical Discharge Machining of AlSiC Metal Matrix Composites
Mwangi J. W.; Ikua B. W.; Nyakoe G. N.; Zeidler H; Kabini S. K
Metal Matrix Composites (MMC) belong to a new generation
of engineering materials that have desirable qualities such as
high strength-to-weight ratio, high toughness, low value of coefficient
of thermal expansion, high wear resistance, and thermal stability.
They are therefore increasingly finding applications in the areas of
aerospace, automotive, defense, biological and nuclear energy fields.
Due to the nature of their application, these materials require to be
machined to a high accuracy and to have a good surface finish. This
requirement poses a challenge due to hard and abrasive nature of
the materials. Mostly, grinding is the process used but the process
is expensive and slow. Electrical Discharge Machining (EDM) can
be used to address these challenges since it can be used to machine
electrically conducting materials irrespective of their hardness.
This paper investigates the effect of using oil and deionised
water as the dielectric fluids as well as the effect of introducing
low frequency vibration in EDM machining of Aluminium Silicon
Carbide (AlSiC) MMC. Experiments were carried out on AlSiC
(AMC225XE) material using Sarix-100 high precision micro-erosion
machine. A series of experiments were carried out with and without
workpiece vibrations. For the experiments with vibrations a vibration
frequency of 900Hz was used. The results of this study indicate that
introduction of vibration raises the material removal rate but results
to an inferior surface quality. Using deionised water as the dielectric
results in lower machining time as opposed to Oil. However, this also
results in an inferior surface quality and geometry of bore.
2017-05-24T00:00:00ZEffect of Capacitance on Electrical Discharge Machining Using an RC type Pulse Generation CircuitKabini S. K.Bojer S. K.Ikua B. W.Kihiu J. M.Nyakoe G. N.Mwangi J. W.http://localhost/xmlui/handle/123456789/31862017-05-24T12:58:46Z2017-05-24T00:00:00ZEffect of Capacitance on Electrical Discharge Machining Using an RC type Pulse Generation Circuit
Kabini S. K.; Bojer S. K.; Ikua B. W.; Kihiu J. M.; Nyakoe G. N.; Mwangi J. W.
The Electrical Discharge Machining (EDM) Process is
complex in nature partly due to the mechanism of material removal,
and, partly due to the presence of many machining parameters. This
complexity of the EDM process has undermined its full potential
drastically reducing its efficiency. In turn, this has led to relatively
higher consumption of electrical energy, longer machining periods,
higher rate of electrode wear and lower surface quality of the finished
product. Various researchers have used varied approaches with the
aim of optimizing the process.
However, most of these researches have focused on optimization of
one or at most two parameters and have used either fuzzy logic
control techniques or modeling approaches. Others have used purely
predictive and non-realtime approaches. All of these do not offer the
advantage of realtime control of the process.
This paper focuses on experimental work carried out to establish
the effect of capacitance on the EDM process. This is part of an
ongoing research who’s aim is to study the EDM process with a view
to designing a controller that is capable of improving the process’
efficiency by optimizing all the machining parameters in realtime
2017-05-24T00:00:00ZDevelopments in Silicon Wafer MicromachiningMulembo, T.Ikua, B.Keraita, J.Niyibizi, A.Wangui, E.http://localhost/xmlui/handle/123456789/31852017-05-24T12:50:36Z2017-05-24T00:00:00ZDevelopments in Silicon Wafer Micromachining
Mulembo, T.; Ikua, B.; Keraita, J.; Niyibizi, A.; Wangui, E.
Most electronic components are based on
monocrystalline silicon, with only a small percentage of them
made of polycrystalline and amorphous silicon. Micromechanical
components such as acceleration sensors in car safety systems and
micro-fluidic circuits are also made of monocrystalline silicon. The
machining of complex shapes from hard and brittle materials such
as monocrystalline silicon still remains a critical area of research.
This paper explores the current status of research and
developments in micromachining of silicon. Special focus is
paid on the cutting methods employed in slicing and dicing of
the silicon. Areas of concern that call for further research and
development in micromachining of silicon are also discussed. It is
expected that this paper will expose the challenging issues of silicon
micromaching and wafer slicing and dicing, and also stimulate
research interests in this area.
2017-05-24T00:00:00ZAn Evaluation of Maintenance Practices in Kenya: Some preliminary resultsMuchiri, A.K.Ikua, B.W.Nyakoe G. NKabini S. KMakenzi M. Mhttp://localhost/xmlui/handle/123456789/31842017-05-24T12:43:48Z2017-05-24T00:00:00ZAn Evaluation of Maintenance Practices in Kenya: Some preliminary results
Muchiri, A.K.; Ikua, B.W.; Nyakoe G. N; Kabini S. K; Makenzi M. M
Over time, the definition of maintenance has evolved
from activities meant to keep equipment in an operable condition, to
a set of activities required to keep the means of production in the desired
operating conditions or to restore them to this condition. Further,
all those systematic activities geared towards the actual execution and
improvement of maintenance are referred to as Maintenance practices.
There is a general assumption that maintenance practices in the
developing world are below standard, when compared to what
happens in the developed world. However, this is not a fact that
has been determined empirically, but rather a perception. This paper
presents the results of an assessment of maintenance practices in
Kenyan industries, using a maintenance practices evaluation tool.
The analysis provides a critical overview of the current status of
maintenance practices and also how these maintenance practices
compare with the best practices globally. The research was carried
out through a survey, using a questionnaire developed to establish the
maintenance practices in a number of Kenyan companies. The survey
clustered into different categories, namely, service, power generation,
food manufacturing and processing, agro/chemical, metal processing,
motor vehicle assemblers, transport, maintenance and construction
industries. The responses from the survey were analyzed using the
three aspects of maintenance practices, namely, technical, managerial
and human aspects. For each of these aspects, an evaluation index
was developed and calculated. Subsequently, the general evaluation
index was determined. This index showed that Kenyan companies
are at the managed level of maintenance practices. At this level,
the processes are partially planned and performance depends on the
operators’ experience and competence.
It is recommended that the companies aim at improving the index to
the highest level, namely the optimizing stage.
2017-05-24T00:00:00Z