Maricris Enrile

QCMO-MGH YIELD IMPROVEMENT 99.58 % to 99.85 % Yield Target Maricris Enrile, Jogie Ann Lato, Shiela Ann Cabonegro Process Engineering Team MinebeaMitsumi Inc., MRI Special Economic Zone, Sabang, Danao City, Cebu -,-, - ​ Abstract ASAF 57S8 (QC) & ASAF 57D8 (MO) Program Models started mass production after series of experiments. QCMO-MGH under MAT-D1 Division serves as the supply hub of MAT-D2 12th Bldg. MGH consist only of two materials, which is the Magnet Holder and the damping plate. Based on ending March 2021 yield, it is at 99.58% (below target yield of 99.85%). It resulted to disposal amounting to ¥311,308.30 with 0.06 yen/pc ratio. Based on the analysis the major yield blockers of the MGH section were identified: (1) Shifted Damping Plate; (2) MGH damage/deform; and (3) NG Welding. In order to solve this, the team uses DMAIC approach by defining references & target measures to achieve , next conduct evaluation by identifying root causes , conduct series of DOE’s and use quality tools for thorough evaluation and effectiveness of experiments and lastly providing countermeasure based on test results. Through this implementations, QCMO-MGH yield result from 99.58 % it improved to 99.85 % with improvement rate of 0.27%. With these improvements, it had led to a total savings of ¥345,418.56 which has become highly beneficial for the company profitability and committed to company’s direction to reduce disposal. 1. 0 Introduction ASAF 57S8 (QC) & ASAF 57D8 (MO) Program Models started mass production after series of experiments. QCMO-MGH under MAT-D1 Division serves as the supply hub of MAT-D2 12th Bldg. MGH consist only of two materials, which is the Magnet Holder and the Damping Plate. In order to have a better understanding on the rejects of MGH, it is needed to know the process and its concepts. Figure 1. MGH Process Illustration As data shows below, start-up yield of different model for QC-MGH it was only 99.67% while for MO-MGH 99.49% with an over-all yield of 99.58%. Graph 1.QCMO-MGH Yield Target Graph To understand yield loss of this section, pareto of rejects is shown to give highlights & prioritization of items which needed depth analysis. Figure 2 MGH Rejects In response to this, MAT-D1's Technical Team created a MGH yield improvement. Hence, experiments were conducted and analysis of data were done to thoroughly understand and distinguish its root cause(s). Strategies were also handed out to produce the most effective countermeasure to improve and achieve the target yield of 99.85% 2. 0 REVIEW OF RELATED WORK Not applicable 3.0 METHODOLOGY For this project, the team uses DMAIC approach for better understanding. For the DEFINE phase, a summary of outline is stated to have a citation and advise for the team members. On the MEASURE phase, the team set target by accumulating and collecting data which is used for metrics of this project study. It is then followed by ANALYZE and IMPROVE phase, where each top rejects each month are identified, performed root cause analysis using brainstorming, comprehensive analysis, process mapping and collecting data. Based on this, the team develops possible assumptions as to why this reject occur. To further analyze, a better understanding and good teamwork of this is needed by verifying actual condition and samples of reject occurrence in the line. Hence, a set of experiment may require for data analysis and using quality tools for comparing before and after results of experiments. After results of experiments, a recommendation is given for implementing solutions. Lastly for the CONTROL phase, the sustainability of the implemented countermeasure is here stated. For material (referring to magnet holder or damping plate only) related causes, dimension was measured on Nexiv program for accurate measurement results. For material jigs-machine (weight cap, magnet, etc) related causes, dimensions was checked on the material involved. Minitab & Graphical Tools & tables were used for comparing results. For process related causes, a surveillance / motion study is required in order to catch/ verify the actual scenario as to why rejects are occurred. Then countermeasure are systematically based on the results of series of experiments. For maintaining solutions, the team uses different approach. For modification of material related, the team negotiate a designer and involved divisions for approval and revisions drawings of modified design and molding schedule. For machine parts modification, it was coordinated and approved with equipment team for modifying machine related. Actual verification of implemented solutions were performed by the patrol by checking the line and sustainability of the solutions. 3.1 Define Phase Based on P-chart, a detailed reject items with quantity & yield is generated. It was in A2.0 (build before mass production) used as reference data. Top rejects were identified and conducted a process mapping as to where particular machine the reject occur. 3.2 Measure Phase The team agreed to set target of QCMO-MGH yield by the end of this term of 99.85%. Yield will be the primary key metrics used in the project. Graph 2. QCMO MGH Yield Target 3.3 Analyze & Improve Phase Based on the monthly generated pareto chart top rejects were 1.) Shifted Damping Plate, 2) MGH Damage /Deform 3) NG Welding between MGH and Damping Plate 3.3.1 Analysis for Shifted Damping Plate 3.3.1.1 Motion Study The team installed a camera on the damping plate machine. Below logs shows damping plate is already shifted in the pallete. Based on root cause analysis it shows the following causes (1) NG handling of DP Pallete & (2) No Appearance check of DP Condition .See Figure 4 below. 3.3.1.2 Shifted Damping Experiment The team perform a set of DOE. The factor of our DOE are as follows: (a) Condition Check, (b) Takt Time, (c) Manpower Ratio The Condition Check refers to performing Appearance of DP Plate & no App. Of Damping Plate. Takt Time is the time performed of DP Plate Reverse process and also include appearance check & no app. Check. Manpower Ratio is the appropriate pax/line of offline operator to be maximize Factors 1 2 A Condition Check No. App Check App. Check B Takt Time 30 60 C Manpower Ratio 1 pax : 6 lines 1 pax : 5 lines The proponents conducted the DOE to determine the significant factor that have effect. The following are the illustrations of result. It shows that only the Factor A & AB which is Condition check only and combination of condition check + Taktime has siginificant effect on DOE. 3.3.1.3 Shifted Damping Improvement Action Above mentioned effects of condition check and takt time. The proponent’s countermeasure is to provide appearance of DP Material and provide longer takt time for preparation + appearance. Figure 6 QCMO MGH Layout Comparison 3.3.2. Magnet Holder Damage/Deform 3.3.2.1 Analysis for Magnet Holder Damage/Deform In this reject it was stratified based on the location of damage/deform appearance. Most of the damage are on SIDE portion with 58.17% Side portion is again divided into two areas, the upper and lower. Most of damage are on Side Upper portion of the product. Based on why- why analysis, the team found out the ff. causes 3.3.2.2 Magnet Holder Damage/Deform DOE The team perform a set of DOE . The factor of our DOE are as follows: The MGH Alignment refers to the position of MGH Assy if titled or not. V- Dim refers to the material where the DP Cut MC will cut . And Damper Set MC is the MC used during cutting & where the damage occurs. The proponents conducted the DOE to determine the significant factor that have effect. The following are the illustrations of result We checked the v dimensions of damping plate And shows that all are with-in the specification, But it need to be modified since the damping cut machine cannot cut immediately this portion. Figure 10 Damping Plate V-Notch Dimension Figure 11 Boxplot of DP V-Dimension 3.3.2.3 Magnet Holder Improvement Action Since we cannot modify the dimension of the material since economically it affects the suppliers’ spare parts which as feedback to them will increase and create more repairable in their die parts. The team focuses on maximizing the damper cut machine settings. Figure 12 Excess DP Cut Machine Setting Figure 12 shows the best DP Cut Machine setting use Based on the performed experiment of settings. 3.3.3. NG Welding Between MGH & Damping Plate 3.3.3.1 Analysis for NG Welding Between MGH & Damping Plate NG Welding is where the appearance of the welded boss has damage causing the damping plate attached to be moved detached. 3.3.3.2 Welding Height vs Peel-Off Evaluation The team gathered different sets of welding height and check its breaking power to decide what welding specification must be used. Results shows that the under 0.040~ 0.050 mm welding height has good quality of breaking power or peel off strength. ONE WAY Anova shows significant effect of these interaction. See Figure 16. Box plot shows a trend of these relationship where the said welding height mentioned above has the greatest results among all DOE set performed. Box plot shows a trend of these relationship where the said welding height mentioned above has the greatest results among all DOE set performed. Box plot shows a trend of these relationship where the said welding height mentioned above has the greatest results among all DOE set performed. Box plot shows a trend of these relationship where the said welding height mentioned above has the greatest results among all DOE set performed. 3.3.3.3 Welding Height vs Peel-Off Improvement Action The team focuses on changing the welding height of QCMO-MGH Magnet Holder to 0.040 ~ 0.050 mm to have a better welding height appearance & high peel off data. 4.0 Results and Discussion After several countermeasure were implemented for the yield improvement of QCMO-Magnet Holder Assy from April 2021 to Sept 2021. Result shows that there is an increase of 0.27% from 99.58% to 99.85%. Figure 17 QCMO MGH Yield Trend from April 2021 to Oct 2021 Figure 18 Top Reject Trend Figure 18 shows also the downtrend of top rejects mentioned in the Analyze Phase. It shows that all top rejects where effectively reduced. 5.0 Conclusion All the countermeasures were effective, thus improvement of yield and almost achieving the target with an equivalent tangible saving of ¥345,418.56. Through DMAIC Approach, the team were able to identify potential causes of failure and provide countermeasure to address the problem and achieve the target. 6.0 Recommendations The team highly recommends to conduct further investigation on the said potential rejects for continuous improvement. Also to be benchmarked by other models also recommended to only that is applicable or have same concept of this project. 7.0 Acknowledgment We would like to express our gratitude and heartfelt to those people who are behind this project from start to beginning: MAT –A/D1 Management, Technical, Equipment, QA, ECS, Raw Material and Production Teams and to our DOE coach Mr. Bryan Gobaco. These people have given us something that they can never take back which is their time, effort and support. Without them we cannot proceed and achieved this kind of success. And also to God that always gave us a presence of mind, guidance, gifts and talent that He has bestowed upon us and all those who given aid to this project. 8.0 References 1. R.M. Khan, Problem Solving and Data Analysis Using Minitab, Wiley, 1 Edition, 2013 2. Dr. R. Lakhe and K. Dharkar, Quality Control Tools: 7 QC Tools (RRL Book 5), Kindle Edition, 2018 3. J.S Oakland, Statistical Process Control 6th Edition, 4. Butterworth-Heinemann; 6th Edition, 2007 9.0 About the AuthorS Engr. Maricris Enrile Educational Attainment: BS in Industrial Engineering Employment History: MinebeaMitsumi (2015-Present) Jogie Ann Lato Educational Attainment: BS in Industrial Technology Employment History: MinebeaMitsumi (2018-Present) Shiela Ann Cabonegro Educational Attainment: BS in Industrial Technology Employment History: MinebeaMitsumi (2020-Present)