Analysis and Control of Production Cost of Automobile Wiring Harness


Analysis and Control of Production Cost of Automobile Wiring Harness


The wiring harness is a very important component of modern vehicles such as automobiles, an important carrier for connect various electrical parts of automobile and nervous system for vehicle power distribution and signal transmission. With the development and progress of the automobile and electronic industries, people's expectations for safety, handling, comfort, entertainment and other aspects of the automobile are getting higher and higher. Especially in recent years, the addition of new energy vehicles has greatly promoted the The industry is developing rapidly in the direction of electronic control, comfort, intelligence and automation. With the application of a large number of electronic and electronic control products in automobiles, wiring harness connections are becoming more and more complex, the number of circuits has increased dramatically, and the proportion of wiring harnesses in the cost of automobiles has continued to rise. In some models, the cost is even second only to engines and transmissions. part. The number of wiring harness materials for the whole vehicle is tens of thousands, the manufacturing process is cumbersome, and the cost accounting workload is large, but there are still basis and rules to follow. However, wire harness tooling and molds often require tens of millions of investment. If the purchaser lacks the ability to evaluate its quantity and real cost, it is difficult to evaluate the rationality of the supplier's quotation information, and there is no effective evaluation basis for price negotiation and pricing decision-making. In turn, it may bring unnecessary economic losses to the company. This article will discuss the cost analysis of tooling and die based on the wire harness manufacturing process and bill of materials, and give suggestions for cost control.

Classification of automotive wiring harnesses

According to the complexity of the structure, it can be divided into main wiring harness and small wiring harness. The main wiring harness has a complex structure and is composed of many materials. There are many branches on one main line, and there are assembly direction requirements, mainly referring to the wiring harness of the engine compartment, the wiring harness of the instrument panel, and the wiring harness of the body. The structure of the small wiring harness is simple, and there are few or no branch lines, such as air conditioner wiring harness, seat wiring harness, door panel wiring harness, bumper wiring harness, ceiling wiring harness, trunk wiring harness, etc.

Wire harness manufacturing process

The main cost of wire harness is raw material cost and manufacturing cost, as well as tooling and mold cost. The cost of raw materials can be calculated and accumulated item by item according to the wire harness bill of materials. Wire harness assembly manufacturing is highly labor-intensive, and the number of materials for the entire vehicle wiring harness is large, resulting in complex and cumbersome manufacturing processes, and a relatively low degree of mechanization and automation. Although individual single processes can be automated or semi-automated production, the overall process is difficult. The realization of automated manufacturing mainly depends on the manual work of workers. If the management is not in place, it is easy to mix materials and incorrectly install and miss the phenomenon, resulting in the scrap or rework of the entire set of wiring harnesses. Figure 3 is a brief manufacturing process flow of the wiring harness. The manufacturing process is reasonably designed according to the 2D drawing of the wiring harness, which mainly includes several major processes such as wire opening, terminal crimping, wiring harness assembly, and continuity testing. The complexity of the wiring harness is different, the assembly line and the manufacturing process are different, and the wiring harness will continuously adjust and optimize the process in the assembly manufacturing, and the cost changes dynamically within a small range. Compared with the total cost fluctuation value, it is completely in accordance with the manufacturing process. Accounting costs are very tedious and time-consuming and need to be updated constantly, which is of little significance. The usual practice in the industry is to calculate the cost of raw materials, and inversely calculate the manufacturing cost and total cost of the wire harness with reference to a certain proportion; this proportion is based on the consumption of the wire harness factory other than the raw materials and the output of the wire harness, and converts the non-raw material of each set of wire harnesses. consumption cost.

The manufacture of wire harnesses will use a lot of equipment and tooling, and general equipment and tooling are depreciated into manufacturing expenses. Special equipment and tooling should be invested as fixed assets, and their costs should be accounted for. Through the introduction of the manufacturing process, the wire harness tooling dies that should be regarded as fixed assets are:  terminal crimping die;  tooling plate;  induction table, clip table, electrical measuring table. The fixed asset investment cost of the vehicle wiring harness is closely related to the structural complexity of the wiring harness.