Quality control (QC) is an essential part of any manufacturing process. Incoming Quality Control (IQC), in particular, aims at preventing that defective components make their way into production and cause expensive delays and quality issues. It takes place when parts coming into the factory are inspected before they are transformed/assembled.
In this post, we break down the role of IQC in a broader quality management system, explaining how different QC gates work together to catch defects early.
You’ll learn:
- Why relying solely on in-process or final QC inspections is risky
- How suppliers’ quality affects overall manufacturing efficiency
- What happens when an incoming batch of parts fails IQC
When you’re done, you’ll understand the importance of a well-defined IQC process and how it helps prevent costly surprises in production.
What’s the purpose of IQC?
The purpose of incoming QC inspections is to avoid having defective parts or components even getting to production. The goal is for IQC to detect all defective batches of components.
If, on the assembly line, we still find some obviously defective parts (by operators mostly, and by a patrolling in-process QC inspector), we put them aside, but we should not have to rely on staff on the assembly line for this.
We also perform an outgoing QC inspection on every batch, but only on a small proportion of the pieces, so again just relying on that is not good practice.
Where Incoming Quality Control fits in for us
At a high level, the way we work is as follows. You can see Incoming Quality Control (in red) right in the center of the journey from a customer’s order to shipment of their completed products:
Our QC gates
To summarize, we put in place the following QC gates:
1. We communicate requirements to the suppliers, and we request them to prepare their own QC report on every batch.
2. IQC at Agilian: random check by incoming QC inspection; may be 100% check on specific high-value components.
3. In-Process QC at Agilian: 100% check by operators* + random check by patrolling QC inspection.
4. Automated visual inspection on 100% of final products (when required).
5. OQC at Agilian: random outgoing QC inspection after packaging.
*(Keeping in mind that some operators act as in-line QC inspectors, and others are less discerning.)
Each one is a filter, in a way, and visual inspection by humans can never catch 100% of issues. The IQC filter is one of the most important, and we endeavor to help the IQC inspectors do the best possible job.
That’s why we keep asking our customers for information, to align on what is acceptable. This way, component manufacturers know what is expected and can focus on ensuring quality “at the source”, and we are less likely to have unwelcome surprises about costs going up at the last moment (or worse, a supplier refusing any future order).
In theory, we should not have to check what component suppliers do. But in practice we really, really need the IQC filter for all suppliers’ goods, as component quality issues are a daily challenge in China.
Devising appropriate acceptance criteria
In general, the more specific and objectively-assessable the acceptance criteria are for parts coming from suppliers, the better. We wrote before about what makes a good quality standard which discusses the essential characteristics that define an effective quality standard, emphasizing the importance of clear, measurable criteria and consistent application to ensure product excellence.
We also wrote about the use of limit samples as a very good practice, which clarifies the differences between golden samples and limit samples.
How about for components we make ourselves, like the plastic and silicone parts we make at Agilian Plastic & Molds?
The short answer is that we don’t want to have a specific process just for that situation. We want the same logic for all suppliers, whether they are internal to our group or not.
An inspector works there full-time and acts as the inspector of Agilian Plastic & Molds. And then the parts go through Agilian’s incoming QC inspection process as described.
Common FAQs about IQC
Here are some common questions that are worth answering:
Q: “What normally happens when an incoming batch of parts fails Incoming Quality Control?”
The batch goes to the Quality Project Manager (QPM), which differs per project, and, in some cases, they might contact the customer with a question – especially if the issue is not something that was specified before and we are not sure whether it is acceptable or not. What happens next depends on the situation and there are easy and complicated scenarios:
- Easy scenario: If a high proportion of the parts are defective, that is clearly unacceptable according to the pre-set criteria, the batch is rejected, and the supplier either reworks or reproduces parts and then presents them again to us.
- Complicated scenario: For example, if time is quite short and it seems that about 10% of the parts have an issue, we may decide to push them to assembly and perform a 100% sorting job there. In such a case, we may find that 5% of the parts have that issue, or maybe 20% have that issue, with a risk of short shipment. This type of situation impacts the ability to deliver in full and gives a bit more work to the assembly team. In some other, trickier situations, the impact can be huge.
Q: Is there any real penalty to having a relaxed IQC well below what is acceptable at FQC?
That would not make sense. Rejecting products after they have been assembled for a defect on a part that could have been flagged in incoming QC doesn’t make sense. As a general rule, defects should be caught and contained as close to the source as possible. The further away from the source, the higher the impact in time and cost.
You should also read…
You may also enjoy these blog posts.
- How A Material Review Board (MRB) Works & Why YOUR Factory Needs One, explains the role of an MRB in evaluating and deciding the disposition of nonconforming materials, highlighting its importance in maintaining quality and efficiency within manufacturing operations.
- Why Skipping Incoming QC Is a Source of High Risks & Costs, emphasizes the critical role of incoming quality control in identifying defects early, thereby preventing costly issues during production and ensuring product reliability.
- Typical Problems with Electronic Contract Manufacturers in China, outlines common challenges faced when working with these manufacturers, including poor product quality, inadequate quality management, and insufficient supplier oversight.
