That day, three batches of goods were simultaneously held by the production line
"Hey, Engineer, come here for a moment!"
Do you remember? Once, when I was guiding a novice on a line tour, we had just reached the wet etch area when the team leader urgently called out to me. He pointed to three batches of goods covered with yellow plastic sheets beside three machines, his expression quite displeased.
"Team Leader, what's wrong with these three batches?" I asked.
"What else could be wrong? They're all anomalous! One batch had an optical inspection anomaly, with DPMO skyrocketing to 8000; another had machine parameters drift, with Cpk dropping to 1.08; the most outrageous was the third batch, where an operator's hand slipped and directly overturned the product tray!" The team leader grew angrier as he spoke.
I looked at the three batches of goods, thinking to myself, 'This is going to be interesting.' Aren't these typical 'non-conforming products'? The key is how to handle them afterwards—that's the real skill.
Where's the Problem? Not That It's Unnoticeable, But There's No SOP
To put it bluntly, non-conforming product control, while sounding professional, essentially teaches you how to manage 'defective' or 'problematic' products. You might say, "Who doesn't know this? If it's broken, just throw it away!"
It's not that simple!
Look at those three batches of goods just now: some had quality issues, some had process issues, and some were due to human error. Without a standardized procedure, if everyone handles things based on their own feelings, major problems will arise. At best, a batch of goods is scrapped; at worst, an entire batch is shipped out, leading to customer complaints—that's no laughing matter.
Therefore, the key is that we need an SOP for "Isolation, Identification, and Disposition Decision" to ensure these problematic products do not flow into the next process, much less leave the factory.
How Is It Actually Done? Three Unmissable Steps
Our factory's SOP roughly runs as follows:
- Isolation:
* Physical Isolation: Like the team leader, cover it with yellow plastic sheeting, or place it directly on a dedicated red material rack. Our SOP requires that it must be separated from normal products; they cannot be mixed. This is like isolating the sick to prevent them from infecting healthy people.
- Identification:
* System Record: Simultaneously, change the status of this batch in the MES system to "Hold" and meticulously record the anomaly information. This way, it can be tracked from the system side, ensuring no one can bypass the process.
- Disposition Decision:
* Decision Meeting: A meeting is held to decide on a course of action. Common disposition methods include:
* Scrap: Needless to say, it's discarded directly.
* Rework: If the defect can be repaired and the quality meets standards after repair, then rework is performed. However, products that undergo rework typically undergo another round of strict, comprehensive inspection.
* Downgrade: Some products, while not meeting the highest standards, might meet the requirements for other products with lower standards; in such cases, downgrading can be considered. This usually requires customer approval.
* Use-as-is / Concession: This is relatively rare, usually occurring when a customer has an urgent need and agrees to accept the goods, even with a known minor defect. However, this typically requires high-level approval and explicit written consent from the customer.
Simply put, these are the core questions: "Who discovered the problem? What is the problem? Who will handle it? How will it be handled?"
The Most Common Pitfalls: One 'Forget' and It's Game Over
The most outrageous incident I encountered was inadequate isolation. Once, a new engineer found a problematic batch of goods and simply told an operator verbally, "Put this aside for now, don't touch it." As soon as he turned to attend to something else, another operator, who hadn't heard, directly pushed this batch into the next process. By the time it was discovered, it had already been processed, effectively doubling the loss.
There's also unclear identification. Labels merely stated "Defective Product" without specifying the reason or lot number. Consequently, several batches of defective products piled up, making it impossible to distinguish which batch was which. Ultimately, all had to be treated as the most severe case, resulting in unnecessary losses.
Frankly, these issues are all caused by "taking shortcuts" or "forgetfulness." Don't mistake them for minor matters; one oversight can lead to losses of hundreds of thousands or even millions.
One Thing You Can Do Today
Check your production line's non-conforming product area for any anomalous items that are clearly labeled.