100% offset return yesterday: The "cold - treatment" dilemma of asking for acceptance criteria
At 2 p.m. yesterday, I had just finished entering the shipping details of last week into the system when an email about a quality complaint from Customer C popped up. The subject was glaring: "100% assembly deviation in the XX - 2309 batch of products, return the whole batch." The photos in the attachment were even more straightforward: when our chassis was installed on the customer's equipment, the positioning holes didn't align with the pins on the equipment bracket at all, with a deviation of a full 2.5mm (the customer's requirement is ≤0.5mm).
To solve the problem, the first step is to align the inspection standards of both parties. I immediately picked up the phone and called Manager Li in the customer's quality department. The first time, the line was busy; the second time, no one answered; the third time, it went directly to the voicemail. Right after that, I sent an email with attachments. The attachments were our "Assembly Reference Inspection Record" and the "Positioning Hole Dimension Requirements" provided by the customer last year. In the main body of the email, I only asked three questions: "Is the measurement reference for the offset during your company's acceptance inspection the 'bottom surface of the casing' or the'side surface'? Is the measuring tool a coordinate measuring machine or a vernier caliper? Is there a latest standard version?"
Until ten o'clock this morning, the email showed "read" but there was no reply. When I called again, the voice prompt still said, "The number you dialed is not answered for the moment." I looked at the return form on the table - 1,200 pieces of products were being sent back from the customer's warehouse, and each piece was labeled with a red tag reading "assembly unqualified". However, I still had no idea about "what criteria the customer used to judge the products as unqualified", so it was impossible to start the subsequent root - cause analysis.
Return of today's products due to smaller size: The "debate on standards" of being scapegoated by the boss in a meeting
At nine o'clock this morning, I had just unpacked the abnormal feedback package from Customer D - there were three shafts inside. The measured value of the shaft diameter was φ15.8mm, while the tolerance required by the customer was φ16.0±0.1mm, which was exactly 0.2mm smaller. Just then, the internal phone on the table rang. It was Supervisor Wang from the production department: "There's an urgent meeting called by the boss. It says 'The person - in - charge of the Quality Department must attend'."
In the meeting room, the boss was sitting in the main seat, with the customer's return note spread out in front of him. As soon as I sat down, his words were like stones hitting the glass: "Why didn't you detect the shaft diameter during the raw material procurement inspection?" "Where are the size measurement records before shipment?" "Did you confirm with the customer whether the measurement point is the '30mm area in the middle of the shaft' or the 'two ends'?"
I opened the "Incoming Inspection Ledger" and the "Outgoing Inspection Report" on my phone and said, "The raw materials were received last Tuesday. When they arrived, we measured 10 samples with a micrometer. The shaft diameters were all φ16.1mm, which met the standard. Before shipment, according to the 'Measurement Requirements' from the customer in December 2023, we measured 5 points in the 30mm area in the middle of the shaft. The values at each point were between φ15.9 - 16.1mm, and all the records are in the system. The measurement method was taught by the customer during the training in March this year - 'Use a coordinate measuring machine probe to vertically touch the shaft surface and take the average value of three measurements at each point'."
The boss leaned forward and asked, "Then why did the measurement results from the client show a smaller size?" I took out the client's "Measurement Training Record" from last year and said, "When the client came to teach us how to measure in November last year, they clearly stated that 'the measurement point must be within 30mm from the middle of the shaft'. The measurement position is marked on each batch in our report. Could it be that the client has changed the measurement personnel? Or perhaps their equipment hasn't been calibrated?"
The meeting room fell silent instantly. Xiao Wang from the Administrative Department lowered his head and flipped through the records, while Supervisor Wang from the Production Department stared at the tips of his shoes. No one responded, but I knew clearly in my heart that our inspection standard was correct. The problem was that "no one was willing to believe in the standard".
Reflection: With problems cropping up one after another, whose "blind spots" are they exactly?
When I got off work, I walked back to the office with files in my arms. The wind outside the window made the inspection records on the desk rustle. The problems in these two days are not coincidences. Yesterday's deviation was "the inspection benchmark was inconsistent with the customer's assembly benchmark", and today's issue with the size was "the machining feed was increased by 0.05mm". But why were these problems only discovered after the customer received the goods?
I opened the "Process Inspection Record": For the offset batch from yesterday, the process inspection only measured the "positional accuracy of the positioning holes" and did not measure the "reference alignment after assembly"; for the dimensional batch today, the process inspection measured the "shaft diameter" but did not check the "feed rate parameter of the lathe". Suddenly, I realized that our inspection has always been limited to "measuring values according to the standards" and has not carried out "verification based on the actual usage scenarios of the customers" - the customers use the shafts to "fit bearings", so a 0.2mm smaller shaft diameter will cause the bearings to loosen; while our process inspection only measured the "value of the shaft diameter" and did not measure the "fitting clearance between the shaft and the bearing".
What's even worse is that as the quality supervisor, I didn't take the initiative to check the "latest standards" with the customers. Manager Li of Customer C changed positions last month. Has the new contact person updated the measurement benchmark? Has the equipment of Customer D just been calibrated, resulting in higher measurement accuracy? I didn't ask any of these questions and only focused on the "old standards" for inspection.
The evening sun shines through the window and falls on the client's drawing on the table. It says "Version: 2023 - 10 - 01" in the top - right corner of the drawing, while the inspection record in my hand is still using the "2022 - 05 - 01" version. So that's it - it's not that the client's standards have changed; it's that I've "stayed in the past".
Finally: The essence of the problem has never been "whose responsibility it is"
On my way home from work, I stared at the missed calls on my phone. Manager Li from Client C finally returned my call and said, "The new measurement benchmark is 'the two locating pin holes on the bottom surface of the casing'. It was updated last week, and I forgot to inform you." The quality supervisor from Client D also sent a message: "Our CMM has just been calibrated, and the measurement accuracy has been improved from ±0.02mm to ±0.01mm, so a deviation of 0.2mm can be detected."
Suddenly, I realized that the problems in the past two days have never been "I didn't get stuck with the raw materials" or "I didn't measure the product size" — but rather "Our standards are not synchronized with those of the customers" and "Our inspections are not close to the customers' usage scenarios".
When I got home in the evening, I turned on the computer and wrote a "Quality Improvement Plan": Check the latest standards with all customers tomorrow morning; Confirm "Additional measurement of the fit clearance during process inspection" with the production department tomorrow afternoon; Organize a "Simulation of customer measurement scenarios" next week - not to "prove that I'm right", but to "prevent problems from occurring on the customers' side".
After all, quality is never "inspected out", but "grows" from customers' needs.