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When Tesla announced in 2020 that it would reduce the number of parts in the rear floor of the Model Y from 70 to 1, the integrated die-casting technology quickly came into the spotlight.This technology once became a “cost-reducing magic weapon” in the production and manufacturing of new energy vehicles because it can significantly reduce the number of parts and simplify the production process. Amid the roar of large die-casting machines, automakers claimed that “production efficiency has been significantly improved” and “the manufacturing cost per vehicle has decreased by 40%”. Following Tesla, Chinese automakers have followed suit one after another. BYD’s 9,000-ton production line, Xiaomi’s 9,100-ton process, and Dongfeng Motor’s super die-casting factory have been successively put into operation. For a time,die-casting machines with tens of thousands of tons have become the core selling point in automaker’s promotions.

However, behind this bustling equipment race, their is hidden numerical game concerning pass rates. It is understood that the current average pass rate of integrated die castings is only 65% to 80%, which stands in stark contrast to the pass rate of over 98% for traditional stamping parts.

This means that when producing 100 parts, die-casting parts will have at least about 18 more defective products than stamped parts. More importantly, the post-maintenance cost of integrated die-cast parts is four times that of traditional structural parts, and this part of the cost will ultimately be passed on to users. This contradiction is not an isolated case. From fluctuations in pass rates and high equipment investment on the production side, to soaring maintenance costs will ultimately be passed on to users. This contradiction is not an isolated case. From fluctuations in pass rates and high equipment investment on the production side, to soaring maintenance costs on the user side, and then to the ecological adaptation side, to soaring maintenance costs on the user side, and then to the ecological adaptation challenges in the industrial chain, integrated die casting seems to be caught in the dilemma of “advanced technology vs. Uncontrollable costs”.    

Ⅰ.Hidden Worries About Yield Rate Amid Rapid Progress

The low pass rate is particularly evident in the integrated die-casting process.According to a reporter’s research data on multiple automobile companies, during the trial assembly process, their pass rate is only 30% to 40%; after switching to mass production, the pass rate directly increases to about 90%. If the pass rate rises abnormally, it may mean that the quality inspection standards have been relaxed and potential quality problems have been covered up; while a low pass rate will directly lead to a sharp increase in production costs.

It is understood that what is more challenging is that quality defects in integrated die castings are often hidden. There may be tiny internal pores or shrinkage defects that are difficult to detect in initial inspections but will gradually become apparent during the long-term use of the vehicle, ultimately leading to a decline in structural performance. This combination of quality risks and cost pressures constitutes a significant obstacle to the promotion of integrated die casting technology.

In addition, an employee of a certain automobile company once revealed an unspoken rule in the industry: some automobile companies use 8,000-tons machines to die-cast parts that theoretically require 9,000-ton equipment for processing in order to reduce initial investment,resulting in a significant reduction in mold life and a sharp drop in the yield rate to below 50%.

Ⅱ.The Technical Misconceptions Behind The Fluctuations In Pass Rate

Unlike the traditional body structure, which is assembled from dozens or even hundreds of stamped parts through welding and riveting, integrated die-cast parts need to achieve complex functional integration on a single component of several square meters. This shift in design philosophy poses unprecedented challenges to materials science, mold engineering, and process control.

Material performance is one of the core factors affecting the qualified rate. Integrated die casting usually uses light metal materials such as aluminum alloys. The flow characteristics and solidification shrinkage behavior of these material under high temperature and high pressure are directly related to the integrity of the final product. Compared with traditional stamping parts, the solidification process of large die castings is more complex. Uneven temperature field distribution may lead to defects such as internal stress concentration, shrinkage cavities and porosity. At the same time, minor deviations in material formulas or gases involved in the smelting process may cause difficult-to-detect micro-defects in large thin-walled structures.

Both mold design and temperature control systems are also key factors affecting the qualification rate. The surface of a mold covering tens of thousands of square meters needs to maintain a highly uniform temperature distribution; any local overheating or overcooling areas will lead to insufficient material filling or premature solidification. “The die-casting process involves more than 10 variables such as alloy melting temperature and cooling rate, and the hardness at different positions of the same mold may differ by 2 HRC,” said a factory manager. In actual production, it is extremely difficult to control the temperature where the material flow path is long and the resistance is large,making insufficient filling more likely to occur. In addition, the precision and service life of the mold itself directly affect the stability of the quality of die-cast parts. As the number of Production batches increase, minor wear and tear of the mold will gradually accumulate, eventually leading to a decrease in the qualification rate.

The phenomenon mentioned earlier, where the pass rate suddenly jumped from 30% to 40% to 90%, may reflect a breakthrough in parameters during the production debugging process. However, it is worth in-depth investigation whether this breakthrough is based on scientific process control or merely achieved by relaxing inspection standards. A significant improvement in the pass rate in a short period can sometimes mask deeper quality issues, such as an increase in the missed detection rate of internal defects. These potential risks may gradually emerge after the vehicles have been in use for several years.

Ⅲ.The Whole-life Cycle Cost Is A Huge Challenge

The issue of qualified product rate directly points to the most sensitive pain point of integrated die-casting technology-cost-effectiveness. On the surface, integrated die-casting reduces production costs by reducing the number of parts and simplifying the assembly process. However, when factors such as losses from unqualified products, equipment depreciation, mold wear and tear, and later maintenance costs are taken into consideration, the economic viability of this technology needs to be reassessed.

Faced with these challenges, automobile manufacturers need to adopt a more rational attitude. On the one hand, they should increase investment in research and development in materials science, mold design, and process control, and improve the qualification rate through technological innovation. On the other hand, they should establish a full-life-cycle cost assessment model, which not only considers manufacturing costs but also comprehensively takes into account influencing factors such as maintenance costs, insurance expenses, and residual value rates, so as to provide a more comprehensive decision-making basis for the selection of technical routes.

From Tesla’s technological revolution to the collective follow-up by Chinese automakers, the development history of integrated die casting is essentially a microcosm of the transformation of the automotive manufacturing industry from “priority to scale” to “balance between quality and cost”. Undoubtedly, integrated die casting technology represents an important development direction in automotive manufacturing processes. However, solving the cost dilemma requires joint efforts from the industry. Only by finding a balance between pass rate, maintenance economy, and full-life-cycle costs can this technology truly demonstrate its value, rather than becoming a marketing gimmick.

When the roar of ten-thousand-ton die-casting machines is no longer overshadowed by cost anxieties, and when consumers no longer have to pay an extra price for technological innovations, this manufacturing revolution can truly realize its industrial value—not only an improvement in production efficiency, but also a sustainable upgrade of the entire automotive industry chain.