Masters Of Science In Advanced Manufacturing and Automation Engineeringhttp://repository.dkut.ac.ke:8080/xmlui/handle/123456789/6632024-03-28T16:13:55Z2024-03-28T16:13:55ZQuality Failure Analysis And Quality Improvement Methods In Small and Medium Manufacturing CompaniesNgugi, Joseph Chegehttp://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7232018-04-23T12:12:47Z2017-08-01T00:00:00ZQuality Failure Analysis And Quality Improvement Methods In Small and Medium Manufacturing Companies
Ngugi, Joseph Chege
n.
ABSTRACT
Quality is one of the strategic goals for any manufacturing companies to satisfy the
customers' needs. Moreover, managing quality supports differentiation, low cost and
response strategies to enjoy the competitive advantage. The modern global market
demands that products produced and services rendered meet certain quality standards.
However, many small and medium manufacturing organizations in Kenya fail to
satisfy the needs of the customers for not being attentive to quality improvement. As a
result many customers return the manufactured products for reworking or completely
reject them. The organizations in return incur losses due to these problems which keep
on recurring and therefore fail to compete well in the market. The occurrence of these
quality problems are as a result of lack of quality management improvement methods.
This study therefore analyzed quality failures and established quality improvement
methods that are needed in steel furniture manufacturing companies to solve the
identified quality problems. This will ensure that the manufactured steel furniture
attract customers and enjoy fair competition in the market.
The study adopted a case study methodology in shamco a steel furniture
manufacturing company in Nairobi Kenya. Both primary and secondary data were
used from the year 2014-2016. The primary data collected included the severity,
occurrence and detect ability of the defects identified by the customers. The methods
used to collect the primary data were interviews and brainstorming. 11 participants
were drawn from the four departments after conducting a survey based on their
responsibilities in the departments and their knowledge on quality matters. They were
clustered in six groups. In the data analysis Failure Mode and Effect Analysis
(FMEA) was applied to prioritize the defects through risk priority numbers (RPN).
Root cause analysis was carried out for each defect and cause and effect diagrams
(ishikawa diagrams) were used on the basis of machines, workers, materials and
process. Pareto analysis was used to distinguish major causes from trivial ones.
The study established that the most critical defects included breaking of welding
joints, scratches, unbalanced ground instability, chipping and faint paint just to name
a few. The study found that their really existed critical defects which affected quality.
The root causes of these defects were as a result of workers with a response of 35%,
process had a response of 30%, materials had a response of 24% and machines had a
response of 11 % of the participants. After establishing the defects and their root
causes, practical solutions to minimize or eliminate each of these causes were
established.
This research contributed to knowledge of practice by giving crucial practical
remedial methods of which some have been implemented with positive results. The
success of the improvement methods is highly dependent on the support from the top
management through resource allocation, involvement of the employees through
commitment suppliers and any other stakeholder in the manufacturing process
through dissemination of correct information.
Abstract
2017-08-01T00:00:00ZDevelopment Of Cost Effective Strategy For Inventory Control; A Case Study of Cement Manufacturing Company In KenyaBarmasai, Jacob Kiplagathttp://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7222018-04-23T12:09:17Z2017-09-01T00:00:00ZDevelopment Of Cost Effective Strategy For Inventory Control; A Case Study of Cement Manufacturing Company In Kenya
Barmasai, Jacob Kiplagat
Inventory management is essential to many organizations mainly because it avails production goods and
spares when required. Due to increasing competition from globalization in the business environment
especially manufacturing sector, many companies within Kenya in the recent past have been hit by
financial constrains and are in the quest of improving their financial status by optimizing production
resources in order to increase profit margin and remain competitive. In the cement factory under this
study (BTC), expenditures on various spares and raw material contribute significantly to high cost that
result in poor financial performance. The purpose of this research was to determine the optimal spending
on spare parts and raw materials storage activities at BTC with the aim of lowering the overall inventory
cost.
This research is a case study with inductive approach whereby, data from BTC was collected and
analyzed to obtain various cost factors associated with spares and raw materials acquisition and storage.
Root cause analysis was used to identify various causes of inventory challenges, whereas inventory
turnover ratio was used to establish monetary utility of the existing system on maintaining spares,
materials and goods. Pareto analysis was conducted to identify crucial and sensitive commodities that
contributed significantly to the overall inventory cost. Subsequently, systematic applications of Economic
Order Quantity (EOQ) and Selective Control (A-class B-class C-class/ABC) were used to determine the
optimum operation strategy for inventory management.
This research outlines projected changes to inventory system at BTC. Design-out of existing material
transport system was done whereby through analysis it was established that it would have a payback
period in within its lifespan. EOQ and ABC inventory control is set for implementation within the
financial year 2018, while the goods conveyor system, would be operational in the year 2019.
Abstract
2017-09-01T00:00:00ZPreperation And Characterization Of Biodegradable Composites Based On Polylactic Acid Reinforced With Renewable Fibers And CopolymerHassan, Langat Kipyegonhttp://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7212018-04-23T12:06:14Z2017-07-01T00:00:00ZPreperation And Characterization Of Biodegradable Composites Based On Polylactic Acid Reinforced With Renewable Fibers And Copolymer
Hassan, Langat Kipyegon
Composites have widely been used in the past due to its attractive characteristics in terms
of high strength in relation to weight. However, they have been derived from petroleum
products which are difficult to dispose. Environmental issues and awareness globally has
attracted much research into the development of sustainable composites.
Polylactic Acid is sugar based biodegradable polymer and possesses attractive properties
that makes it a suitable polymer material for sustainable composites production. However,
there arc other properties that limits its application and include: low thermal stability.
reduced mechanical performance compared to polypropylene, polyethylene and
polystyrene. This study therefore aims at preparation, characterization and comparison of
PLA biodegradable composite from Kraft cellulose, wood fiber, Lyocell cellulose and
Viscous cellulose with and without Desmodur as a copolymer.
In the study, properties of PLA were improved by compounding and hot pressing it with
different natural commercial and readily available fibers of Kraft cellulose, wood fiber,
viscose, Lyocell® and Cordenka® in mass proportions of l 0%, 20% and 30% relative to
the matrix PLA with 10% of an additional copolymer. Charpy impact strength, tensile
strength, thermal properties and morphology were investigated and compared for all
composites and their possible applications. It was found that Charpy impact strength
reduced with increase in fiber content with highest impact of (63 kJ/m2) at 10% viscose
fiber loading. A high tensile strength of 67 MPa was obtained from 30% Lyocell fiber in
the composite which was 4 MPa and 10 MPa higher than that of Kraft cellulose at the 30%
fiber loading and pure PLA respectively. Modulus of elasticity reached a maximum value
of 6 GPa at 30 % loading of Kraft cellulose. Addition of copolymer showed reduced
stiffness for all the composites due to impregnation of the active sites instead of bonding hence did not improve the fiber-matrix interaction. Scanning electron micrographs of the
fractured surface showed better fiber-matrix interface, fiber pullout and the active role
played by fibers in absorbing energy thus enhancing the mechanical properties. Water
absorption on the other hand showed prolonged water uptake. Thermal analysis for
composite without copolymer revealed a stable crystal structure whereas those with
copolymer showed different melting peaks indicative of the presence of different phases in
the structure. The results obtained show that the properties of PLA can be enhanced by
addition of natural fibers in cellulosic form such as Kraft cellulose, Lyocell and Viscose
cellulose. The contribution of this research in practice it the cost reduction associated with
blend of expensive PLA with commercial readily available cellulose fibers which reduces
the cost of these composites and expected to open up an avenue in which these
biodegradable composites can be utilized in this applications to replace the components
made from non-biodegradable polymers. Scientifically, the application of copolymer-
Desmodur, a blocked polyisocyanate stable at room temperature and dissociates to
regenerate isocyanate functionality when heated to 160° C, easily reacting with terminal
both hydroxyl and carboxyl group present in PLA and Cellulose fiber at melting
temperature of PLA. This resulted in a new ductile material, with good interface between
matrix and cellulose fibers.
Abstract
2017-07-01T00:00:00ZExperimental Investigation And Optimization Of Laser Cutting Parameters For Solar Cell Based On Taguchi MethodMbithi, Benson Kilonzohttp://repository.dkut.ac.ke:8080/xmlui/handle/123456789/7202018-04-23T11:55:49Z2017-09-01T00:00:00ZExperimental Investigation And Optimization Of Laser Cutting Parameters For Solar Cell Based On Taguchi Method
Mbithi, Benson Kilonzo
In recent times, laser material processing has become a mainstream manufacturing technique
in micromachining applications. This trend has been due to the various unique properties of
the laser beam. Laser machining has excellent properties such as flexibility which make it to
be used for cutting, welding, and drilling almost any material including silicon. In solar cell
cutting, the input parameters dictate the quality of the final product.
The manufacture of customized solar panels has presented some challenges such as micro
cracking, material waste due to kerf, and low machining rate. The optimal conditions may be
realized by having optimal input parameters combination in the machining process. Therefore,
there is the need for optimization of the input parameters so as to produce quality solar panels.
In this research, the effect of laser beam and process variables (inputs) on cut quality
attributes of solar cell were investigated. Parameter ranking was done to determine the most
significant parameters on the final product. The input parameters selected for this study were:
laser power, scan speed, and spct diameter, The quality attributes (outputs) which were
investigated were: keri' depth, kerf width and material removal rate for the process.
The input parameters were used in the design of experiment by Taguchi 9-orthogonal array
implemented in Minitab 17 software. The design provided nine experiments for unique
combinations of the input parameters. Experiments were then conducted and the results were
tabulated and analyzed.
The input parameters were found to have a significant effect on the quality attributes of the
solar cell. The kerf depth was found to increase with increasing laser power and decreased
with increasing spot diameter and scan speed. The kerf width was found to increase with
increasing laser power and spot diameter while it decreased with increasing scan speed. On the other hand, material removal rate was found to increase with increasing laser power and
spot diameter while scan speed had the opposite effect. From this analysis, models relating the
responses to the input factors were developed with the aid of the software.
Optimization process provided the solution for the desirable set values for the responses i.e.
kerf depth was set at a target value of O. l 840mm, the kerf width was set to be at the
minimum, and the material removal rate was set to be at the maximum to reduce machining
time. The optimal conditions were found to be; laser power at l 26.67W, spot diameter at
0.4158111111 and the scan speed at 3121mm/min.
An experimental validation of the optimized conditions was conducted obtaining kerf depth at
0.1839mrn with a standard deviation of 0.00001, kerf width at 0.5828111111 with a standard
deviation of 0.0005 and material removal rate at l 456mm3 /min with a standard deviation of
1.76. These experimental results showed conformity to the optimal conditions obtained using
the software.
In conclusion, the study showed that the input parameters selected have a significant effect on
the selected output parameters for the laser cutting process of solar cells. It was also found
that the obtained optimal parameters for laser cutting of solar cell produced the optimal
response factors after machining process.
Abstract
2017-09-01T00:00:00Z