CTION REPORT CORRECTIVE A 8 DISCIPLINE APPROACH Concern No.: 753273822
Concern Title: Machining defect in the valve hole Part Name:
Wheel
Initial Report Date: Aug/06/2024 To: Plant: Dept:
1. Team Members:
Leader:
Recorder
Members:
BMW Quality
Part Number: 807199701(Prime 479R)
Position Quality Manager Position Quality Engineer Position PMC Manager Eng. Manager Quality Section Chief Production Manager CNC Section Chief
2. Concern Description:
July 23th 2024, BMW notified that they found a machining defect in the valve hole wheel of the P.N. 807199701(Prime 479R). Please refer to the picture of the issue below.
FQA54 Rev. Initial 9/15/00
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CTION REPORT CORRECTIVE A 8 DISCIPLINE APPROACH
3. Containment Actions: 1. All inventories have been finished sorting, totally 100 pieces are all good wheels, certified shipments
will be with certification label on each pallet. Date completed…2024-07-24
2. Quality alert was released to all the appearance inspectors and the related production operators.
Date completed…2024-07-23
Certification Label: Quality Alert:
4. Root Cause:
Specific:
1. After confirmation the traceability information, the CNC time of the wheel is 2024/03/27 02:00, and it is
processed in CNC NO. #33 line. All the characteristics related valve hole were measured, valve hole land thickness is undersized.
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CTION REPORT CORRECTIVE A 8 DISCIPLINE APPROACH 2. According to the analysis the sample forwarded from BMW, this imperfection should inccurred in the CNC
process, we walked through the whole process, reviewed the production conditions and production records, found that the control of the process following the requirements of SOP.
3. After confirming the return of the wheel, we found that the lug hole position size within the spec, only the
valve hole land thickness is undersized, this is caused by our current CNC process. total of two groups of holes need to be processed in the drilling process, the first step is to drill the valve hole, if the B axis of the boring machine has not been cleaned of machining chips, there will accumulated under the wheel base level, as the machining stroke is fixed, the valve hole land thickness is thinned when the upper bit is
pressed down, and this will result the quantity of drilling is larger and casued similar defects. In the drill of valve hole processing, due to the downward pressure, the chips will be crushed or burst away, so in the second step of lug hole processing, the relevant sizes are not greatly affected due to far away from the base level or the chips have been crushed or burst away. Schematic diagram of Machining chips accumulated Normal drilling under the wheel base level
The current work step
Step1 drill the valve hole Step2 drill the lug hole
Machining chips
4. A replication study was done to confirm that the cause of the valve hole land thickness undersized.
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CTION REPORT CORRECTIVE A 8 DISCIPLINE APPROACH
Machining chips Valve hole appearance
CMM measurement results of replication study sample, similar of customer feedback defect Detection:
1. We have a clear standard on the floor that the operator is required to use gage to 100% check this
size and is equipped with the corresponding gage in this process, for somehow the operator missed this wheel’s check.
Valve hole land thickness gage Using gage to 100% check valve hole land thickness FQA54 Rev. Initial 9/15/00
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CTION REPORT CORRECTIVE A 8 DISCIPLINE APPROACH
Valve hole land thickness 100% gage check SOP 5. Immediate Corrective Actions:
1. Improve the internal flushing of the boring machine, timely dredge the pipeline, to avoid flushing
lessen than normality resulting in the accumulation of machining chips in B axis of the boring machine. Target date…2024-08-04
2. Regularly (every 2H) clean the machining chips of drilling machine B axis to prevent the
accumulation to affecting the base level. Target date…2024-08-04
3. Change the machining step of this procedure from the first step machining the valve hole second the
lug hole to the first step machining the lug hole second the valve hole, once chips are piled on the base level, they will be crushed or burst away during machining the lug hole. Target date…2024-08-06
4. Retraining operators and educate them to carry out 100% gage check. Target date…2024-08-06
5. Increaseing the CNC supervisor's verify on 100% gage check implement status every two hours.
Target date…2024-08-07
6. Implementation of Permanent Corrective Actions: 1. Improved the internal flushing of the boring machine, timely dredge the pipeline, to avoid flushing
lessen than normality resulting in the accumulation of machining chips in B axis of the boring machine, it is OK currently.
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8D_807199701(479R) Machining defect in the valve hole 8D
