结构件工程师跳槽,总要会点儿STAR法则讲case的英语

1. 根本原因分析：

• 通过三次元测量和电子显微镜检查，发现刀具路径在转角处存在轴向分层残留

• 使用切削力仿真软件验证了主轴转速与进给匹配不当导致的刀具微颤振

• 分析得出主要原因：5轴姿态变换时A/C轴联动加速度参数未优化，造成离心力突变

2. 改善方案：

• 重新设计刀具路径：采用“螺旋渐近式”切入策略，替代原直角分层法

• 参数优化：将主轴转速从28,000rpm调整为32,000rpm，进给率由4,500mm/min降至3,800mm/min

• 引入动态精度补偿：在CNC程序中嵌入实时挠度补偿算法（基于MATLAB开发的专用模块）

• 设计专用检测治具：采用蓝光扫描替代接触式探针，实现100%在线检测

3. 验证流程：

• 进行DoE实验设计（3因素3水平），确认最优参数组合

• 制作500件验证批，跟踪三班生产稳定性

• 与苹果SQE联合评审，获得工程变更批准（ECR#2023-078）

R（结果）

1. 不良率从8%降至0.6%，优于目标值

2. 单件加工时间仅增加9%（符合≤20%要求）

3. 改善方案被纳入《iPhone结构件加工标准手册》第3.2章

4. 年度质量成本降低约$280,000，获部门技术创新奖

5. 方法论被推广至iPad和MacBook中框产线

English Version

S (Situation)

During the mass production phase of iPhone 15 mid-frame, we encountered micro-transition steps on R-angle (radius 0.5mm) surfaces post-CNC machining. Located at the antenna breakpoint and sidewall junction, this five-axis precision process showed an 8% defect rate, affecting visual quality and assembly fit.

T (Task)

Appointed as technical lead, I was tasked with reducing the defect rate to below 1% within two weeks while maintaining machining efficiency (cycle time ≤120% of original) and ensuring seamless integration into the production line.

A (Action)

1. Root Cause Analysis:

• CMM and SEM inspection revealed axial layering residues at toolpath transitions

• Cutting force simulation identified tool micro-chatter due to inappropriate speed/feed matching

• Primary cause: Unoptimized A/C-axis acceleration during 5-axis reorientation caused centrifugal force spikes

2. Improvements:

• Redesigned toolpath: Implemented "helical progressive" entry strategy instead of perpendicular layering

• Parameter optimization: Adjusted spindle speed from 28,000 to 32,000rpm, feed rate from 4,500 to 3,800mm/min

• Embedded real-time deflection compensation algorithm in CNC program (custom MATLAB module)

• Developed dedicated blue-light scanning fixture for 100% inline inspection

3. Validation:

• Conducted DoE (3-factor, 3-level) to confirm optimal parameters

• 500-piece trial batch across three shifts confirmed stability

• Joint review with Apple SQE secured engineering change approval (ECR#2023-078)

R (Result)

1. Defect rate reduced from 8% to 0.6%, exceeding target

2. Cycle time increased only 9% (within 20% limit)

3. Solution documented in Structural Machining Standards ManualChapter 3.2

4. Annual quality cost reduced by ~$280,000, earning departmental innovation award

5. Methodology extended to iPad and MacBook mid-frame production lines