The key process in valve production

The definition of the key process is the process that determines the quality of the product. The key process mainly has the following five sources: ① the process of forming key characteristics; ② the process of forming important characteristics; ③ the process of difficult processing; ④ the process of unstable quality; ⑤ the process of easily causing major economic losses. The first two sources are generally determined in the design, while the latter three sources are closely related to the process and production.

The first is the difficult process of processing. For example, a new valve stem of ours has a diameter of 16, a total length of more than 700, and a length-to-diameter ratio of more than 40. It is definitely difficult to ensure straightness and coaxiality during the machining process and can be listed as a key process. There is also the internal parts of our delicate control valve. The oblique plane is processed on the slender orifice. How to detect it is actually difficult, and it is not an exaggeration to list it as a key process. For the difficult process of processing, we must consider the six factors of human, machine, material, method, environment and measurement. It is especially worth noting that this link of "testing" is easy to overlook.

The other is a process of unstable quality. For example, for one of our large-volume products, a 10% ratio of knife-bending phenomenon occurred in the deep hole processing of a certain part, which brought a lot of waste to the assembly, and the proportion of the same problems with the previous batches of products was only 1- 2%, then we will list this process as a key process for control. It is worth noting that "processes with unstable quality" must be distinguished from "special processes". Sometimes these two processes have me in you and you in me. How to distinguish between these two processes will be discussed in the follow-up micro-text.

The last one is a process that can easily cause major economic losses. For the valve industry, this process is mainly to pay attention to the price of the parts, including the price of the blank and the price of processing.

For example, a new control valve of ours has special valve body material, difficult to obtain blanks, and expensive, so it must be listed as a key process. The other is the processing of parts. Some equipment is only available in China at only three or two, and the cost of outsourcing is high. This must also be listed as a key process to be controlled.

It should be pointed out that we need to evaluate the difficult process and the process with unstable quality on a regular basis, because some difficult processes can be solved by the enterprise through the investment of people and equipment. Once the resources are invested, the original Some processes do not need to be included in the key process. For the process of unstable quality, we use root cause analysis or other tools to find the root cause. After the resource input, the problem is solved, and the original process does not need to be included in the key process.