**7. Conclusion**

• To develop preventive maintenance program for critical machinery and/

The research methodology adopted in this study was a descriptive survey type since this research method accurately describes the relation between variables, increase fairness, and maximize the reliability of the data. The method provides straightforward summaries about the sample and the observations that have been made. This ensured that appropriate answers are obtained for the research questions. The data collecting techniques employed in this work is: subject matter literature surveys using: journal articles, books, related thesis papers; survey questionnaires; unstructured interview questions; visit and assessment of secondary sources such as factory maintenance log book, annual finance reports, published documents, and

The data used in this study have been collected from primary and secondary sources. Primary sources focused on information that helps to have entire understanding of the study through different techniques such as interviews, questionnaires, observations, and discussions, whereas secondary sources of information related to the study have detail understanding with the supportive documents and

Non-random sampling which is purposive technique was selected in this study because this type of sampling is extremely functional to construct reality, describe a phenomenon or build up an impressive about a universe using specific knowledge.

The sample for this study is taken from the target population of maintenance department, production department, and management parts of AWF at the two

Population variability, availability of participants, and the suitability to the required information are factors considered when the sample size is determined. Eqs. (4) and (5) are used to determine the sample size since the population is finite.

Ns <sup>¼</sup> *<sup>N</sup>*

Z = value of level of confidence (consider 90% confidence level, Z is 1.645) P = percentage picking a choice expressed as decimal 0.5 used for sample size

Applying Eqs. (3.1) and (3.2), the target sample size is determined as:

The first part of the questionnaires presented on the six parameters was discussed in primary data analysis, and the result is summarized as follows:

<sup>1</sup> <sup>þ</sup> *<sup>N</sup>*�<sup>1</sup> *No*

*<sup>P</sup>*ð Þ <sup>1</sup> � <sup>P</sup> *<sup>=</sup>*C<sup>2</sup> (4)

(5)

<sup>N</sup> <sup>¼</sup> *<sup>Z</sup>*<sup>2</sup>

C = confidence initial expressed as decimal 0.08 = +/� 8%

reports. Both quantitative and qualitative data were collected.

This sampling strategy is feasible to quantitative researches.

where N = sample unit (initial sample size)

No = size of the population (214 in this study)

Ns = size of targeted sample

N = 105 and Ns = 70

equipment

work order sheets.

sites (Lideta and Mekanisa)

needed

**6. Summary**

**326**

**5. Research design and target population**

*Operations Management - Emerging Trend in the Digital Era*

The aim of this study was to enhance productivity of Awash Wine Factory through improved maintenance management system. The basic maintenance problems of the factory were investigated, and smart maintenance system that decrease machine down time and reduce maintenance cost is recommended. Data collected through questionnaires, unstructured interview, visit and document analyses were used to identify the major causes of the problem. Case and effect diagram and failure mode effect and criticality analysis were used as a tool to differentiate the root cause of the problems. The collected data were analyzed by SPSS software, and the following results were obtained. The company has got problems of highest machine breakdown time and high yearly maintenance cost due to wrong maintenance strategy, poor maintenance management system, and repeated failure of washer machine. As a result, the company has lost more than 12% of its yearly product and incurred much money as cost of maintenance.

After the analysis, this study has suggested ways to enhance productivity and increase competitiveness of the factory in the modern market. The recommended maintenance system incorporates preventive maintenance as maintenance strategy and CMMS as a maintenance management tool with their respective merits explained in the fifth chapter of the study. New annual maintenance program for critical machines like washer machine is developed. The suggested smart maintenance system helps to decrease machine downtimes, increase availability of the machinery, and reduce maintenance costs through the creation of a sense of ownership in each of the plant-equipment operators, maintainers, and support staff so as to encourage "a prevention of problems at source" attitude. Implementing the new maintenance system, the factory will generate many benefits. For instance, considering the present efficiency of the company leaving other factors, the yearly product loss due to machine break down will be reduced from 12 to 6%.

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