Solve the quality of the outer surface of a 200-liter closed steel drum (1)

QC results report

Solve the quality of the outer surface of a 200-liter closed steel drum (1)

Dalian Co., Ltd.

I. Overview of the QC team

Our QC team is a QC team (Figure 1, Table 1) with technicians as the main body and quality management personnel and technology archivists. After the establishment of the group, it mainly focused on how to improve product quality, improve quality management, and carry out technical research on quality key. The specific conditions of the quality management of the whole plant were selected and targeted, and achieved certain results. The QC team played an active role in quality management.

Figure 1 Panelist Pie Chart

Table 1 QC team personnel profile

Second, the reason for the topic

According to the goal of “strengthening management, improving quality and increasing efficiency” proposed by our factory's annual factory policy, we have chosen the main contradiction affecting the various business objectives of our factory – the quality problem of the outer surface coating of 200L closed steel drum is the key issue. . If there is a breakthrough in this subject, it can be. Significantly reduce consumption, improve efficiency, and promote the development of enterprises.

Third, determine the target and feasibility analysis

The target is: the passing quality of the outer surface of the 200L closed steel drum is more than 97%. The annual saving value is about 500,000 yuan.

Feasibility analysis: According to the 1988 quality statistics, the unqualified rate of the outer surface coating of 200L closed steel drums is over 40%, accounting for more than 80% of the non-conforming products of the whole factory. The reason for this problem is that there is a layer of mineral oil on the surface of the imported steel plate, which causes the paint to have poor adhesion and the paint film to fall off. If the problem of oil stain on the surface of the steel plate is solved, the pass rate of the product can be greatly improved, and the unit cost can be reduced by about 5 yuan, which can completely reach the predetermined target value. Therefore, this topic is feasible.

Fourth, investigate the status quo and find out the problem

While strengthening management, establishing quality management institutions at all levels, and conducting quality education and training, we conducted a comprehensive analysis of the quality of the main products of the whole plant and plotted the layout (Figure 2).

Table 2 Statistical Table of Major Products Nonconforming Product (January-May)

Figure 2: Number of non-conforming product loss

From January to May, the number of non-conforming products in the whole factory was 54,974. From the Barrett curve of the arrangement chart, among the four main products of the whole plant, the number of unqualified 200L closed steel drums is 50,642, accounting for 92%, which is the largest variety of non-conforming products. Based on the facts, we found the key reasons for the production of non-conforming products.

There are 4 main products in our factory: 200L closed steel drum, 34～45L shrink barrel, 80L closed steel drum and 30L zinc chloride steel drum. In order to further clarify the quality of these four varieties, we listed the loss of the amount of non-conforming products of major products from January to May according to the price of materials and the repair costs of non-conforming products (Figure 3).

Table 2 Statistics on the amount of non-conforming product loss

Figure 3: Non-conforming product loss amount arrangement chart

From Figure 3, we can see that the 200L closed steel drum has 77.8% of the loss of non-conforming products from January to May, followed by 8.3% of the shrinkage barrels, and 5.8% of the 80L closed steel drums. Barrels account for 3.8%, but what are the main reasons for the quality problems of 200L closed steel drums? Classify the causes of non-conforming products and list the unqualified arrangement of 200L closed steel drums (Figure 4).

Table 4 Statistics on the causes of non-conforming products of 200-liter closed steel drum

Figure 4: Reasons for the failure of the 200-liter closed steel drum

It can be seen from the Barrett curve of Fig. 4 that the unqualified product caused by the exterior painting process reaches 84.4%, which is obviously the main factor, and other processes account for 15.6%, which is a secondary factor. The problem of the quality of the exterior paint is so common, and the number of non-conforming products is so high. To this end, the engineering capability of the process must be investigated. From the finished product of the process, we randomly sample 100 steel drums, measure the film thickness, take out the data (Table 5), draw a histogram (Figure 5), and calculate the process capability index Cpk=0.49, (Table 6). . In addition, observing the histogram, and compared with the process size of the paint film thickness of 20 ± 3. Oμm, it can be seen that the actual size distribution range is too large, resulting in an out of tolerance, measures should be taken to reduce.

Based on this, we have focused on the key process of the exterior paint and set goals, steps and measures in the 200L closed steel drum, which mainly affects the quality of our factory (Figure 6).

Table 5 Measured film thickness (unit: μm)

Description: La - the maximum value in the data; Sm - the minimum value in the data

Figure 5 film thickness layout

Figure 6 PDCA cycle diagram

Table 6 Frequency Distribution Table

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