Incoming Inspection

1.Incoming Inspection

Incoming inspection refers to the confirmation and verification of the quality of purchased raw materials, components, or products, that is, the quality is inspected through sampling when the supplier sends the raw materials or components, and the final judgment is made whether the batch of products is accepted or rejected.

2.Meaning

IQC is the first quality control level for enterprise products before production. If unqualified products are placed in the manufacturing process, it can lead to unqualified processes or final products, causing huge losses. IQC not only affects the quality of the company’s final products, but also affects various direct or indirect costs.

    In the manufacturing industry, the four main items that directly affect product quality are usually design, incoming materials, process, and storage and transportation. Generally, design accounts for 25%, incoming materials account for 50%, process accounts for 20%, and storage and transportation accounts for 1% to 5%.

In summary, incoming material inspection plays an overwhelming role in the quality of the company’s products, so it is necessary to elevate incoming material quality control to a strategic position.

3 Responsibilities

    The main job of an inspector is to inspect incoming materials, while IQC inspection can be briefly described as confirming all or the main characteristics of outsourced or purchased materials by referring to the relevant standards of the materials; Or activities to confirm whether it meets the usage requirements.

• Handling material quality issues

IQC also needs to track and handle quality issues discovered during the inspection process, as well as major material quality issues reported by production and market feedback, and establish preventive measures within IQC.

• Statistics and feedback on material quality issues throughout the entire process

Collect quality data during the process of receiving and inspecting incoming materials, and provide feedback to relevant departments in the form of weekly and monthly reports as the basis for supplier quality control and management of incoming materials.

• Participate in process optimization for material related departments

Participate in the optimization of relevant processes in the logistics control process, and provide suggestions and opinions on the optimization of processes related to logistics and material inspection.

4. Inspection methods
5. Incoming inspection, also known as acceptance inspection, is a control point for preventing defective materials from entering the material warehouse and is also the main source of information for evaluating suppliers.
6. The quality reliability of the supplier and the quantity, unit price, volume, etc. of the materials shall be planned as full inspection, random inspection, and exemption from inspection. The requirements are as follows:
7. Full inspection: small quantity, high unit price;
8. Sampling: Materials with large quantities or frequent occurrences;
9. Exemption from inspection: Materials with a large quantity, low unit price, or general subsidies, or certified as exempt manufacturers or limited materials;

5 .Sampling inspection

Applicable occasions

Acceptance sampling is often used by customers to evaluate whether a supplier’s batch of incoming materials is acceptable. The advantages of acceptance sampling will be particularly prominent in the following situations.

.Require destructive testing of incoming materials.

.Due to cost and time constraints, full inspection cannot be achieved.

.The acceptable products of incoming suppliers have a good historical record.

Analysis of Related Nouns

attribute data

The counting sampling plan mainly determines whether the incoming batch is acceptable based on the number of defects in the batch. The 0 defect plan is also included in the count based sampling plan, which mainly determines whether the incoming material is acceptable by checking whether the acceptable quality level (AQL) is within the acceptable range, that is, only a certain number of defective products.

variable data

  Metrological sampling plans are mainly based on measurement results to determine whether incoming materials are acceptable. Considering cost and efficiency, measurement based sampling plans typically require significantly fewer sampling quantities than attribute based sampling plans.

  The quantitative sampling plan of SPC software is mainly based on the following four input parameters: acceptable quality level (AQL), batch allowable defect rate (LTPD), producer risk, and customer risk.

Acceptable Quality Level (AQL)

The acceptable quality level (AQL) is usually defined as the rate of non conformities that can be accepted for a submitted batch at 95%. 95% of the time, submit batches that receive quality equivalent to or higher than AQL. If a batch is rejected, there is 95% confidence that the quality of the batch is inferior to AQL. Similarly, the probability of rejection for batches with AQL quality is 5%. AQL is not the necessary quality level for the produced or received batch. It’s not even a quality goal. It is only a producer risk（ α) Or a simple percentage of non conformities based on the probability of rejecting acceptable batches.

Batch allowable defect rate (LTPD)

The allowable defect rate of a batch is usually defined as the rejection rate at 90%. It can be said that when the batch quality rejection rate is at or worse than LTPD, 90% of the time will be rejected. If the batch is qualified, then there is 90% confidence that the quality of the batch is better than LTPD. It can also be said that the probability of LTPD being accepted is 10% for the delivery batch defect rate. LTPD is customer risk（ β) The defect rate or probability of receiving non-conforming products. The customer split is usually 10%.

6.Inspection items

1. Appearance inspection (usually using visual, tactile, and limit samples)
2. Dimensional and structural inspection (using verniers, micrometers, projectors)
3. Characteristic inspection (using testing instruments or equipment)
4. Electrical characteristic inspection B, chemical characteristic inspection C, physical characteristic inspection
5. Ground characteristic test E, temperature characteristic inspection F, vibration characteristic test
6. Withstand voltage characteristic test G, life characteristic test I, environmental test

7.Working principles

 IQC is a window for companies to interact with suppliers and also a gateway for controlling supplier quality. The progress of IQC work directly affects the quality cost of our products and our impression among suppliers.

① Strict sampling

Sampling inspection is a statistical risk that may result in defective products being missed and placed on the production line, or qualified products being rejected, indirectly causing losses to our company. Therefore, when sampling, it is important to ensure that the sample reflects the quality status of the parent material as much as possible. In the sampling plan, according to current international or national standards, the risk rate can be controlled below 5%. However, in the specific sampling process, personal preferences may cause insufficient randomness of the mother body, so special attention should be paid to rigor in the sampling method.

② Evaluate quality objectively and fairly

1. IQC personnel often interact with suppliers to create an “emotional atmosphere”, which can easily lead to subjective awareness during inspection, resulting in differences in the judgment standards for suppliers.
2. Affected by personal mood, being in a good mood may be more serious, and testing and judgment may be more cautious; Being in a bad mood may be like setting the world at once.
3. Due to the influence of the personality of the inspectors, people who are impatient are prone to subjective judgments, so it is important to pay attention to objectivity and fairness. If unqualified batches are placed in the manufacturing process and raw material problems occur, IQC personnel will be held responsible first.

③ Respect suppliers

④ Judging by comprehensive factors

During inspection, there may be conflicts in terms of quality, time, cost, and efficiency. For example, if raw materials need to be urgently launched and there is a “minor issue” found during inspection that cannot be accepted according to the original standards, the company’s procurement strategy is to use materials at lower prices. Although there are differences from the original quality goals, it is still possible to accept them.

⑤ Try not to make special purchases

⑥ Clear identification during the inspection process

Use label identification to distinguish between inspected products, defective products, qualified products, etc. It is best to stick them on colored labels for differentiation.