Views: 0 Author: Site Editor Publish Time: 2026-07-09 Origin: Site
This project focused on the production pain points of a core transmission component supplier for a joint-venture automobile manufacturer. A dedicated development and optimization project was carried out for high-life and high-stability die-casting molds for automotive transmission housings.
The die-cast product in this project is made of ADC12 aluminum alloy, with a single-piece weight of 6.8 kg. The customer’s annual production demand reaches 200,000 pieces, making this a large-volume, high-load, continuous die-casting production application.
The customer’s original die-casting molds for similar products had obvious shortcomings in durability and stability. After approximately 50,000 shots, the molds commonly showed a series of problems, including core erosion, flash at the parting surface, ejector pin seizure, and excessive casting deformation. These issues caused frequent shutdowns for mold maintenance, high maintenance costs, reduced production line efficiency, and lower product yield, making it difficult to meet the requirements of continuous large-scale production.
Based on these production bottlenecks, the customer urgently needed comprehensive optimization of mold structure, process, material selection, and temperature control systems to improve overall mold service life, production stability, and mass-production cost efficiency.
Based on the customer’s on-site mass-production data and mold disassembly inspection results, the project team accurately identified four major pain points in the original molds. These were also the key factors restricting mold life and product quality.
The original gating structure was not properly designed. High-speed molten metal directly impacted the gate area of the cavity. After only 30,000 shots, obvious pit erosion defects appeared in the mold, directly causing a sharp increase in burrs on the casting surface and significantly increasing the workload of subsequent grinding.
The original ejector pin holes lacked effective sealing and dustproof structures. During production, aluminum chips easily entered the gaps, causing mold sticking, broken pins, ejector pin seizure, and other failures. On average, the line had to be stopped for maintenance every 2,000 shots, seriously interrupting continuous production and causing significant efficiency loss.
The traditional cooling water channel layout was unreasonable, resulting in large temperature differences across different mold areas. This caused significant forming deformation of the transmission housing castings. The rate of products exceeding the machining allowance reached as high as 8%, leading to high scrap and rework costs.
The slider sealing structure had poor durability. Under long-term mass-production conditions, sealing failure occurred easily, resulting in frequent flash defects on castings. Product grinding and post-processing labor hours remained high, and the overall production economy was unsatisfactory.
In response to the four core pain points, the project team relied on die-casting mold flow analysis and precision mold manufacturing technology. Comprehensive upgrades were completed in four dimensions: the gating system, ejector and guiding system, temperature-control and cooling system, and surface treatment process. These improvements were successfully implemented and verified in mass production.
The traditional side gate structure was replaced with a newly designed tangential fan-shaped gate. This effectively dispersed the high-speed impact energy of the molten aluminum alloy and reduced direct flushing wear on the cavity from the source.
For high-risk erosion areas near the gate, an embedded tungsten steel alloy insert structure was adopted, greatly improving local erosion resistance. The erosion-resistant life of core areas increased by more than three times.
At the same time, the cross-sectional area ratio of the runner was precisely optimized to suppress turbulence during molten metal filling, stabilize filling pressure and flow velocity, and further reduce cavity erosion and casting burr defects.
The ejector structure was comprehensively upgraded. The ejector pins adopted a stepped self-lubricating structure and were matched with high-precision ejector plate guide pillars. Ejection deflection was strictly controlled to within 0.01 mm, ensuring a smooth and accurate ejection process.
Dedicated dustproof steps and vent grooves were added to the ejector pin holes. These structures block aluminum chips from entering the gaps, fundamentally eliminating the risks of mold sticking and pin breakage. As a result, the broken pin rate was reduced by 90%.
An innovative dual-safety mechanism combining spring pre-reset and forced reset was also adopted, effectively preventing mold-closing pin collision failures and comprehensively improving the reliability and service life of the ejector system.
The traditional fixed water channel layout was redesigned. The mold cooling channels were fully replanned, and an integrated design combining conformal spot cooling and parallel water circuits was adopted.
For thick and deformation-prone key areas of the transmission housing, such as bearing holes and mounting surfaces, targeted forced cooling was implemented. A dual-loop independently controlled mold temperature controller was also introduced to achieve precise mold temperature control.
The casting demolding temperature was stably controlled at 180 ± 10°C, effectively improving uneven mold temperature distribution. Casting flatness deformation was reduced from the original 0.15 mm to 0.06 mm, significantly improving forming accuracy.
The entire mold cavity was treated with a composite process of precision polishing and PVD coating, achieving a cavity surface roughness of Ra ≤ 0.4 μm. This significantly reduced demolding resistance, with overall demolding force reduced by 35%, while also reducing demolding wear and casting pull-mark defects.
At the same time, the parting surface was precision ground and matched with high accuracy, achieving zero-clearance fitting at the mold closing surface. This completely eliminated metal leakage at the parting surface and casting flash during mass production, greatly reducing post-processing grinding costs.
Since the optimized high-life die-casting molds were put into mass production, they have undergone long-term full-load production verification. Breakthroughs have been achieved in mold life, production efficiency, product quality, and overall cost. All indicators exceeded the customer’s expectations, delivering significant economic benefits and production value.
The optimized mold can stably support continuous production of more than 75,000 shots. Compared with the original mold, service life increased by 50%, and the major overhaul interval was doubled. This greatly reduced the frequency of mold overhaul and replacement, lowering mold maintenance costs and downtime losses.
Through structural and process optimization, the single-mold production cycle was shortened from 75 seconds to 58 seconds. Production efficiency was significantly improved, and daily effective capacity increased by 29%. This perfectly matched the customer’s annual mass-production demand of 200,000 pieces and significantly enhanced the continuity and stability of the production line.
Mold flash and burr defects were basically eliminated, reducing product grinding and post-processing labor hours by 60%. Casting deformation became precisely controllable, and the rate of excessive machining allowance was reduced from 8% to 1.2%. Product yield improved significantly, while rework and scrap costs were greatly reduced.
The improvement in mold durability significantly reduced mold loss costs. The mold amortization cost per shot decreased by 32%. Throughout the year, the project can save the customer more than RMB 1.2 million in comprehensive expenses, including mold maintenance, product machining, rework, and scrap costs.
At present, the standardized high-life transmission housing die-casting mold design solution developed through this project has been successfully promoted and applied to the mold development and optimization of five similar housing products under the same customer. All applications have achieved consistent results in quality improvement, efficiency enhancement, cost reduction, and mold life extension.
This project has formed a replicable and scalable die-casting mold optimization system, providing solid technical support for the customer’s large-scale precision aluminum alloy die-casting production.
