การทดลองเพื่อกำหนดพารามิเตอร์ที่เหมาะสมต่อการลดอัตราความผิดพลาด ในการอ่านเขียนของฮาร์ดดิกส์ไดร์ฟ / นิพนธ์ จิระพัฒน์พิศาล = Experimental determination of proper parameters for reducing bit error rate of hard disk drive / Nipon Jirapatpisan
To reduce bit error rate of hard disk drive that directly affect number of hard disk drives not meeting prime capacity 500GB. Six Sigma Approach is applied not only to study the factors influencing the bit error rate, but also to identify the appropriate operative condition. The study has been undergone according to the five phase improvement models of Six Sigma methodology. The process begins with defining phase, measuring phase, analyzing phase, improving phase and controlling phase respectively. The result of the process is able to determine 25 KPIVs at early process and reduce to 4 KPIVs that have been used to perform an experiment by full factorial 2[superscript k] method. Analysis using statistical techniques by α = 0.05 found 3 factors that influence bit error rate which are HGA diamond like carbon thickness now is 21°A, media over coat thickness now is 22 °A, head and media spacing now is 1.9 nm. The proper factors level for reducing bit error rate are HGA diamond like carbon thickness is 17°A, media over coat thickness is 20°A, head and media spacing is 1.5 nm. The preliminary experiments are also conducted to confirm the result before production. Finally, the results of statistical analysis are set at the process of control phase. The results by Six Sigma Approach applied showed number of hard disk drives that need to downgrade capacity due to bit error rate not meet criteria reduce from 7.05% to 3.24%. The revenue gained back is 38,086,588 BAHT/year. Also found out that ratio of hard disk drive not meeting bit error rate criteria at 25°C and 55°C reduce to 0.42%, there is an opportunity to eliminate these testing in the future but need to consider potential escapee to customer.
