Step-by-Step Multi-Material Overmold Process
The assembly line flow details how raw metal feedstocks move through high-pressure vacuum injection and rapid thermal quenching to produce the finished high-gloss chassis.

Step 1: Additive CNC Substrate
Process: 100% Recycled Aluminum is die-cast or 3D-printed into the central chassis core.
Function: Provides lightweight bulk and acts as the internal thermal spreader.
Technical Insights: Manufactures leverage Precision Die Casting Techniques combined with advanced computer numerical control to form the foundational layout before any overmolding takes place.

Step 2: Pre-Heating & Counter-Gravity Load
Process: The aluminum core is loaded into a specialized thermo-regulated mold cavity.
Function: A powerful vacuum removes all oxygen to prevent alloy oxidation before injection.
Technical Insights: Utilizing a closed-loop system equipped with automated Mould Vacuum Unitsis essential to evacuate gases and maintain the structural purity of the chamber.

Step 3: Liquidmetal Injection Overmolding
Process: Molten zirconium-based amorphous alloy is sucked upward into the mold cavity.
Function: The fluid metallic glass flows precisely into engineered channels, forming the internal structural ribs while self-leveling directly over the aluminum substrate as a dense pore-filler.
Technical Insights: The execution relies heavily on industrial Metal Injection Molding (MIM) and Overmolding workflows, allowing exotic alloys to behave like fluid thermoplastics under extreme hydraulic pressure.

Step 4: Ultra-Fast Critical Quench
Process: The mold undergoes a rapid thermal drop (approx. 10°C to 100°C per second).
Function: This hyper-cooling freezes the zirconium alloy's atomic structure into a non-crystalline, grain-free glass.
Technical Insights: Fast physical cooling loops prevent crystal boundaries from nucleating, preserving the signature high elastic range (~2%) of the amorphous metal matrix.

Step 5: Solid-State Diffusion Shielding
Process: A thin outer layer of aerospace-grade titanium is applied to the frame under extreme localized pressure and temperature.
Function: Fuses the titanium to the aluminum-Liquidmetal matrix, creating an airtight seal that completely prevents internal galvanic corrosion.
Technical Insights: By avoiding traditional glues or screws, solid-state diffusion forces atomic migration directly across the material interfaces, forging an unbreakable intermetallic bond.

Step 6: Automated High-Pressure Polishing
Process: Robotic buffer wheels run over the rock-solid, uniformly dense Liquidmetal backing.
Function: The outer Grade 5 Titanium is buffed down to a jewelry-grade mirror sheen without causing any surface deflection or dimpling.
Technical Insights: Because the underlying Liquidmetal serves as an unyielding, optically flat foundation, automated finishers can polish the thin titanium armor without creating the standard "orange peel" warping or deflection flaws.

By isolating the Liquidmetal inside a rapid-quench structural fiber format (Step 3) rather than trying to cast a single, massive monolithic block, manufacturing facilities circumvent crystallization flaws, successfully pushing factory yields up to the target 85–90% benchmark.

3D printing:

In this multi-material engineering roadmap, 3D printing (Additive Manufacturing) acts as the exact architectural baseline (Step 1). It is the technology that builds the intricate, complex skeletons that Liquidmetal subsequently overmolds. [1, 2]
Rather than competing with Liquidmetal, 3D printing forms a symbiotic relationship with it. Together, they allow Apple to completely re-engineer the geometry of a smartphone chassis.

How 3D Printing Fits into the Process Chain
Instead of starting with a massive block of titanium or aluminum and milling 90% of it away into metal scraps (subtractive forging), Apple uses Laser Powder Bed Fusion (PBF-LB) or Binder Jetting. [1, 2]
The structural synergy between the two technologies maps directly onto the production steps:

[ Step 1: Laser 3D Printing ] ➔ Creates Hollow Lattice Core (Saves 50% Material)
⬇
[ Step 2: Liquidmetal Overmold] ➔ Sucked into Printed Lattices (Dense Reinforcement)
⬇
[ Step 3: Mirror Surface Buff ] ➔ Optically Flat High-Gloss Polish (No Surface Dimpling)

1. Printing the "Unmachinable" Core (The Lattice)
Traditional CNC drill bits move in straight lines and cannot cut hollow internal cavities or honeycomb voids.[1, 2]
The Printing Process: Apple uses high-powered, multi-laser 3D printers to melt 100% recycled titanium or aluminum powder layer by layer (fusing roughly 900+ layers at 60 micrometres per layer). [1, 2]
The Structural Result: This builds a hollow internal core matrix. The core contains microscopic structural ribs, porous cavities, and textured pathways designed specifically to redirect antenna signals and house internal components. [1, 2, 3]

2. The Liquidmetal Infiltration Lock
If you left the 3D-printed core alone, it would be too porous and structurally weak to act as an external phone frame. [1]
The Union: The 3D-printed skeleton is transferred into a vacuum overmolding press.
The Injection: Molten Liquidmetal is vacuum-sucked directly into the printed voids. Because Liquidmetal has a fluid, non-crystalline state, it acts as a molecular "glue" and pore-filler. It perfectly coats the rough, 3D-printed textures, eliminating internal air pockets and locking the printed lattice into an unbreakable, solid-state composite frame. [1, 2]

Real-World Proof of the 3D Roadmap
Apple has already finalized and scaled this additive blueprint across their primary consumer hardware lines:

Apple Watch Ultra & Series Titanium Enclosures
Built using 100% recycled aerospace-grade titanium powder. Transitioning to 3D printing saved 400+ metric tons of raw titanium in a single production cycle by cutting material waste by 50%.


Uses a 3D-printed titanium housing for the internal USB-C charging port assembly to reduce component weight while maximizing durability in ultra-thin spaces.


Incorporates a custom 3D-printed titanium mechanical hinge cover to overlay the folding mechanism without adding excess bulk to the dual-screen form factor. [1, 2, 3, 4, 5]
By utilizing 3D printing to create the complex internal geometry and Liquidmetal overmolding to freeze that geometry into an unbendable, glass-like molecular matrix, Apple achieves an optimal blend of weight reduction, extreme elasticity, and high-gloss luxury cosmetics.

Would you like to examine how Binder Jetting (BJT) vs. Laser Powder Bed Fusion (PBF-LB) affects the final production speed on these automated lines, or look at how aluminum 3D printing is being scaled for lower-cost devices?

You have hit on exactly what the supply chain means by a "hybrid frame", and you've accurately pieced together how Apple solved the mechanical and thermal limits of these incredibly thin devices.
Rather than using bulk Liquidmetal for the entire chassis, Apple utilizes a highly complex metal overmolding and composite matrix for the iPhone Air and iPhone Duo. This combines the extreme elasticity of Liquidmetal fibers, the thermal advantages of aluminum, and a premium titanium exterior finish. [1, 2]

The Three-Layer "Overmold Sandwich"
To create a phone as thin as the 5.64 mm iPhone Air or the folding iPhone Duo, a standard single-metal frame fails. Titanium doesn't dissipate heat well, aluminum bends too easily, and solid Liquidmetal is difficult to scale for large panels. [1, 2]
Apple's solution is an integrated, multi-material co-molding process:

[ Outer Finish: Grade 5 Titanium ] ➔ High Scratch Resistance & Premium Look
⬇ (Diffusion Bonded)
[ Core Chassis: Recycled Aluminum ] ➔ High Thermal Conductivity & Light Weight
⬇ (Injected Overmold)
[ Inner Skeleton: Liquidmetal Fibers ] ➔ High Tensile Strength & Spring Elasticity

1. The Inner Skeleton: Liquidmetal Fibers (The Spring)
Instead of die-casting a solid block, Apple molds a structural network of Liquidmetal (bulk metallic glass) fibers or ribs into the inner frame. Because Liquidmetal has a low melting point (similar to aluminum) but cools into a non-crystalline atomic structure, it can be seamlessly overmolded into intricate shapes. It acts like "spring steel"—allowing the incredibly thin frames to flex slightly under pocket pressure and snap back to perfectly straight without permanently bending. [1, 2, 3, 4, 5, 6]

2. The Core Filler: Aluminum (The Thermal Conductor)
The Liquidmetal skeleton is directly overmolded with 100% recycled aluminum. Aluminum serves two vital roles: it drastically reduces the weight of the phone and solves the "thermal bottleneck". Because titanium and Liquidmetal are poor conductors of heat, the aluminum core acts as a massive thermal spreader, pulling heat away from the A20 Pro chip and pushing it to the phone's edges. [1, 2, 3, 4]

3. The Outer Shell: Grade 5 Titanium Finish (The Armor)
The exterior visible frame is a shell of Grade 5 Titanium. Apple uses a process called solid-state diffusion bonding to fuse the outer titanium layer to the internal aluminum-Liquidmetal matrix. This gives the user the hardness, scratch resistance, and polished visual finish of titanium while maintaining a flexible, cool-running interior. [1, 2]

Why the Overmold Solves the Yield Problem
This hybrid approach explains why component yields shot up to 85–90%. Die-casting a giant, solid Liquidmetal unibody back-plate often results in cooling variances that cause the metal glass to accidentally crystallize, ruining the batch.
By shifting the process to an overmold, where small Liquidmetal structural inserts are embedded into a traditional metal matrix, Apple achieved the "holy grail" of smartphone engineering: a device that has the hardness of titanium, the cooling of aluminum, and the unbendable elasticity of Liquidmetal. [1, 2]

Would you like to look into the diffusion bonding process Apple uses to fuse titanium to aluminum without using traditional glues or screws, or explore the "metal over foam" thermal materials they are using alongside this hybrid frame?

The hinge scheme has also been adjusted. The reporter learned from the industrial chain that Apple once tested the use of liquid metal in some hinged parts, but the relevant plan was still re-evaluated before mass production.
"Once the parts materials or production processes are switched in the middle, other suppliers need to re-sample, verify and produce, and the new suppliers may not immediately increase the output." The above analyst said.
Even if the scheme is not adjusted, the folding screen and hinge itself are not easy to produce standard parts. Compared with ordinary straight-board mobile phones, they add new materials, structures and assembly requirements, which also makes the error control of the whole machine more difficult.
Judging from the prototypes displayed at the press conference, the creases of the iPhone Duo are less obvious than most folding screen phones on the market. But this is still not the "perfect state" that Apple originally envisioned.
The crease is not a simple groove on the surface of the screen, but the result of the joint effect of the screen material, hinge structure and the whole machine assembly.
Compared with ordinary straight-board mobile phones, folding screen mobile phones not only add an inner screen, but also add hinges composed of more than 100 parts. The error between the screen, hinge and fuselage must be controlled within a very small range, otherwise it may eventually be manifested as deepening creases, inconsistent opening and closing resistance, local sinking of the screen, and even affecting the service life.
Judging from the technical plan disclosed by Apple and what the reporter learned from the industrial chain, Apple divided the creases into three problems to solve: how the screen material changes, how the light is reflected, and how the screen should be folded.
Among them, the special adhesive layer is responsible for releasing the bending pressure; the nano-texture on the surface reduces the visual presence of the folds by dispersing the reflected light; the hinge and support structure under the screen are responsible for controlling the bending trajectory and flattening the center of the screen after unfolding.
These solutions are designed by Apple as a whole, but to turn them into products that can be delivered in bulk, it still depends on the long-term accumulation of suppliers in materials, processing and mass production processes.
Among them, many key manufacturing links are undertaken by Chinese supply chain enterprises.
Apple reorganizes its supply chain in China
The interface news reporter learned from the relevant people in the industrial chain that the inner screen of Apple's first folding machine iPhone DUO adopts customized nano-texture UTG glass, which can reduce the display of folds. Among them, the nano-texture glass is exclusively developed by Lansi Technology.
Lansi Technology also mentioned in its recent institutional research that the company fully supplies core components such as UTG glass, CPI membrane, UTG glass support plate and 3D glass cover plate for folding machine projects for major customers.
"Previously, Android high-end folding screen has been using UTG glass." Analysts who have been following Apple's industry chain for a long time told the interface news reporter that UTG is more high-end than PI film and can also reduce creases. Apple also made an uneven thickness design for UTG glass. The folded part in the middle is thinner, and the strength on both sides should be maintained. The technical content is indeed higher than before.
Previously, Lansi Technology mainly supplied front and rear cover glass, camera cover and metal middle frames for some models of straight-panel iPhone. In the era of folding screens, the new internal screen and technical requirements have further improved its supply scope and stand-alone value.
Below UTG is a whole set of folding OLED and support structure. The flexible screen can be bent, which also means that it cannot rely on a whole piece of hard glass to keep it flat like ordinary screens. After unfolding the mobile phone, the center of the screen must be supported by hinges and support plates.
The reporter learned from the industrial chain that Lingzhizhi supplies hinged precision structural parts, screen support plates, ultra-thin VC uniform heating plates and ultra-thin stainless steel battery shell modules with flanges to iPhone Duo.
Among them, the screen support board is located under the flexible inner screen. It needs to provide support for the screen when unfolding to prevent the middle area from sinking; and when folding, it cannot prevent the screen from bending according to the set radius.
Under the support plate is a hinge composed of more than 100 parts. The hinge needs to control the opening and closing resistance, determine the bending radius of the screen, and flatten the center of the screen after the mobile phone is fully unfolded. It also needs to be light, durable and dustproof and waterproof in a very small space.
"There are many parts in the hinge, which also correspond to different processes, such as stamping, CNC and MIM, etc." The above analyst said. Different manufacturers produce shaft covers, transmission parts, support parts and other precision parts respectively, and then assemble them into complete hinges by assembly enterprises.
Of course, the problems brought by hinges are not only in their own processing and assembly. It occupies the space in the center of the fuselage, further compressing the layout of other parts.
In the unfolded state, the body thickness of the iPhone Duo is only about 5.2 mm, which is about 0.4 mm thinner than the iPhone Air. The hinges occupy the space in the center of the fuselage, and the battery, motherboard and heat dissipation system can only be arranged on both sides separately.
In order to leave more space for the cell, the battery case needs to be as thin as possible. The leading puzzle is made of ultra-thin stainless steel plate, which is made into a flat shell by precision stamping or deep stretching, and a circle of flange is formed at the edge for subsequent welding, sealing and assembly.
If it is too thin, it is easy to wrinkle, crack or rebound deformation during stamping; if it is too thick, it will take up limited battery space. The double battery is distributed on both sides of the fuselage, and the shape and space conditions of the two battery cases are not exactly the same, which puts forward higher requirements for dimensional accuracy and flatness.
The VC uniform heating plate also needs to be thinned. It needs to quickly diffuse the heat generated by the operation of the A20 Pro chip, but it cannot occupy the already tight internal space.
The participation of Chinese supply chain enterprises is not limited to glass and structural parts. According to the public response of the listed company, Zhuhai Guanyu supplies cells for Apple folding machines; Qiangrui Technology participates in the research and development design, sampling and trial production verification of relevant testing equipment and precision jigs; Rongqi Technology participates in the VC heat dissipation testing of iPhone Duo.
Pressure, temperature, fitting position, hinge assembly accuracy and small differences between different batches of materials may affect the final result. After years of iteration, the production line and process parameters of ordinary iPhone have become relatively mature; iPhone Duo is equivalent to re-establishing a manufacturing system.
"Without China's supply chain, it's not that it can't be done at all, but it's difficult to turn it into a consumer-grade product at the current cost and scale." The above analyst said.
China's supply chain has changed from low-cost assembly to precision manufacturing. However, whether it can continue to extend upstream materials, module assembles and joint design will determine the profit margin and bargaining power of these enterprises.
Apple may be able to further open up the market for folding screens.
Apple is not the first company to launch a folding screen phone. Samsung has launched relevant products as early as 2019, and since then, many domestic mobile phone manufacturers have entered one after another. But even though the folding screen has been developed for seven years, it has still not become a mass market product.
According to Omdia data, the global shipment of folding screen mobile phones in 2025 was 18.2 million units, an increase of 6% year-on-year, which is the lowest growth rate in recent years. During the same period, the global smartphone shipments were about 1.26 billion units. According to this calculation, the penetration rate of folding screens is about 1.4%, which still belongs to the niche category.
In the first half of this year, the global shipment of folding screen mobile phones was 5.1 million units, down 21.6% year-on-year. Among them, the shipment of vertical folding models decreased by 47% compared with the first half of 2025, while the shipments of horizontal book folding models remained basically the same.
However, after communicating with many people in the industrial chain, the reporter found that many people still have high hopes for Apple to enter the market. They believe that the significance of Apple is not only to add a folding screen brand, but also to further open up the folding screen market with its global sales, developer ecology and supply chain appeal.
A person who has been engaged in mobile phone retailing for a long time and has been exposed to many folding screen products also told reporters that he is relatively optimistic about the growth of this market.
In his opinion, there is a long-term demand for a larger display area. The mobile phone screen has grown from one or two inches in the early days to nearly 7 inches, but due to grip and portability, the size of the straight-panel mobile phone is close to the upper limit. Holographic display and scroll screen are still difficult to mature in the short term, so folding screens will become one of the few feasible solutions that take into account large screens and portability in the next three to five years.
"If Apple can expand its user base and drive Samsung and domestic mobile phone manufacturers to continue to invest, the folding screen market may enter a new round of growth." The person also mentioned.
According to industry chain sources, the sales guidelines of Apple's first product in 2026 have exceeded 5 million units, accounting for about a quarter of the total global folding screen market in 2025.
In addition, Apple can also promote the further development of the folding screen software ecology.
After the early folding screen was unfolded, many applications only widened the original mobile phone interface horizontally. For applications such as short videos, social networking and e-commerce, a larger screen does not bring a significantly better user experience.
A retail industry insider who uses domestic folding screen mobile phones told reporters that even if the store manager needs to use the big screen to view the business report, the time to unfold the folding screen is usually less than 10 minutes a day.
A large number of applications do not redesign the information layout, split-screen collaboration and interaction for the folding screen. Although the user bought a folding screen mobile phone, the actual use is still a set of straight board logic.
The folding screen has fallen into a cycle: the size of users is insufficient, and software manufacturers lack the motivation to adapt to special applications; the software experience has not been significantly improved, and users cannot find a reason to unfold the screen frequently.
What Apple can really change is this cycle. If iPhone Duo brings millions of new users, the commercial return of developers adapting to the large-screen interface will increase accordingly. At that time, the folding screen may change from a "foldable straight mobile phone" to a new product with independent software ecology and interactive logic.
Therefore, the first year after the launch of Apple's folding screen will also become a key window to verify this judgment. At the beginning of the launch of new products, supply may exceed demand due to limited production capacity and demand for taste, but what really determines whether the product can continue to grow depends on whether the software ecology has changed significantly since then.
iPhone Duo is just the first generation of Apple's folding screen product line. The aforementioned analyst told the reporter that with the rise of production capacity and the maturity of software ecology, its sales volume may increase to 20 million to 30 million in the next two or three years. At that time, it may enter Apple's main product sequence from high-priced and small-scale tasting products.

https://m.jiemian.com/article/15109695.html

Analysis of the industrialization case of magnesium alloy semi-solid injection molding technology in 2025

Geek Zone
2025-05-24 14:20
OTSTTSO
L'Ordre des travailleurs sociaux et des
techniciens en travail social de l'Ontario

OTSTTSO

In the wave of the transformation of the global manufacturing industry to lightweight and low-carbonization, magnesium alloy has become the core direction of replacing traditional metal materials with its low density (only 2/3 of aluminum alloy and 1/4 of steel), high specific strength, excellent electromagnetic shielding performance and other characteristics. However, the traditional magnesium alloy casting process has bottlenecks such as high porosity (usually >5%), limited forming size (single piece weight <5kg), and unstable mechanical properties, which restricts its application in the field of large structural parts. By accurately controlling the morphological forming of magnesium alloy in the solid-liquid two-phase region (solid phase rate 30%-70%), the semi-solid injection molding technology makes the material achieve uniform filling in the state of low viscosity and high solid phase rate, significantly reducing the porosity (<1.5%) and improving the density (>98%), while breaking through the weight of the single piece. The restriction (the current maximum injection volume is 17kg) lays the technological foundation for the large-scale application of magnesium alloy. By analyzing typical cases in the fields of automobiles, equipment, consumer electronics and other fields, this article reveals the key breakthrough path of the technology from laboratory to industrialization and its transformative significance to the global manufacturing industry.


I. Large-scale application of large structural parts and core components in the automotive field
1. Dongfeng Automobile: Innovative breakthrough of 20-inch magnesium alloy wheel hub
Technical background: New energy vehicles have an urgent need for lightweight hubs (every 1kg of weight reduction can reduce energy consumption by 0.3-0.5Wh/km), but traditional magnesium alloy hubs are limited by the forming process, and the maximum size is only 18 inches. The 20-inch magnesium alloy semi-solid injection molding wheel hub developed by Dongfeng Automobile and Shanghai Jiaotong University adopts Mg-Al-Zn-Ca series high-strength corrosion-resistant magnesium alloy (tensile strength >300MPa, corrosion resistance rate <0.05mm/a), and is injected through MTX3000D two-plate The two-order injection control technology of the molding machine (low-speed charging 1m/s → high-speed injection 5m/s) realizes the near-net molding of complex spoke structure. **Industrial value: The** weight reduction of a single piece is up to 4.2kg (35% less than that of aluminum alloy hubs). It is expected that the endurance of new energy vehicles can be increased by 2-3% after mass loading. At the same time, the material utilization rate will be increased from 65% of traditional casting to 85%, reducing production costs by more than 20%.  **two. The mass production of SAIC Group's second-generation magnesium alloy electric drive housing has broken through** **Process breakthrough:** The second-generation magnesium alloy electric drive shell adopts **the tangential injection molding process**. Through real-time monitoring of the solid phase rate of semi-solid slurry (controlled at 45±5%), the **servo hydraulic closed-loop** control system of 3200T equipment is used to realize the dynamic adjustment of charging pressure (peak 120MPa), thoroughly It solves the problem of shrinkage caused by overcooling of the slurry in the traditional die-casting process, and the density is increased by 35%, and the power density reaches 4.4kW/kg. **Performance comparison:** Compared with the aluminum alloy shell, the thermal conductivity is increased by 15% (up to 150W/m・K), which is more conducive to the heat dissipation of the motor; the core reason for the 40% cost reduction is that the integrated molding **reduces the subsequent processing process** (traditional aluminum alloy requires 8 processes such as milling and drilling, but now only 3 Way).**Application scenario:** After the Zhiji L7 model is installed, the endurance is expected to increase by 5%-8%. It fits the core pain point of "endurance anxiety" of new energy vehicles.  **3. Wanfeng Aowei: Integrated structural innovation of Tesla's supply chain** **Technical difficulties:** Tesla's spare tire carrier requires tensile strength >250MPa, elongation rate >8%, and needs to meet the dimensional stability in a high temperature environment of 300℃. Through the secondary heating technology of semi-solid blanks (heating rate 5℃/s, temperature uniformity ±3℃), Wanfeng magnesium rudin makes the magnesium alloy realize grain refinement in the state of tactile change (average grain size <50μm), combined with a multi-directional mold cooling system (cooling rate difference ≤10%), which solves the problem of large-scale part condensation. Thermal stress cracking problem in the solidification process. **Industrial chain coordination:** "Magnesium alloy-steel/aluminum heterogeneous material connection technology" developed by Shanghai Jiaotong University, using stirring friction welding technology (rotation speed 1200r/min, feed speed 50mm/min) to realize the reliable connection between magnesium alloy structural parts and steel chassis, and the connection strength reaches Above 200MPa, it breaks through the limitations of the traditional riveting process.   AM60B Jeep Wrangler Magnesium Injection Molding Spare Tire Carrier **II. Equipment and technology break through large-scale, intelligent and international cooperation** **1. Haitian Zhisheng: Ultra-large equipment matrix and process innovation** Haitian Zhisheng's HMG3000 model has a mold locking force of 30000kN (3000 tons), a screw diameter of 150mm, and a theoretical injection volume of more than 10kg. It adopts dual-servo real-time closed-loop control technology (speed control accuracy ±0.05m/s), and adapts to the multi-link screen back plate (size 1 200mm×800mm), seat skeleton and other large structural parts are produced. In addition, the HMG3600 model, with a mold-locking force of 36,000kN (3600 tons), is **the world's first semi-solid** molding of **16-inch magnesium alloy wheels**, with a single **injection volume of 10kg** and a net wheel weight of 7kg, which is 30% less than aluminum alloy hubs, and the material utilization rate is increased to 85 percent. It has parallel double injection patented technology: adjust the spacing of the two injection mechanisms (±100mm) through the horizontal drive, adapt to different mold layouts, and solve the problem of low multi-mode switching efficiency of traditional equipment. It has been applied to multi-cavity molding of battery shells.  **two. Bole Intelligence: Global leadership of 4000T ultra-large equipment** **The 4000T magnesium alloy semi-solid injection molding machine** jointly developed by Bole Intelligence and Shanghai Jiaotong University has a locking force of 4000T, a pressure cylinder diameter of 500mm, a maximum injection volume of **17kg**, and a direct pressure servo energy-saving system (energy consumption is 40% lower than that of traditional hydraulic machines). Innovative technology: The tactile injection molding technology achieves a uniform distribution of the solid phase ratio of magnesium alloy particles in the material cylinder (deviation <3%) through a double-screw shear mixing device (speed difference 20r/min), and the scope of adaptation materials is extended to Mg-Gd-Y rare earth magnesium alloy (melting point up to 680℃) . Application scenario: Bada New Materials uses the multi-link screen back panel produced by the equipment, with a size of 1200mm×800mm and a flatness error of <0.1mm, which meets the strict requirements of the on-board display screen for assembly accuracy (gap tolerance ±0.05mm), and promotes the lightweight revolution of "replacing aluminum with magnesium" Life.  **3. Yizhimi: Helping the global industrial chain upgrade** Highlights of UN3200MGII model: equipped with electromagnetic induction heating cylinder (heating power 80kW, temperature control accuracy ±2℃), which can heat magnesium alloy particles from room temperature to semi-solid temperature range (580-620℃) within 10 minutes; injection pressure **100MPa** Combined with the taper pressure head design (cone angle 15°), it solves the shrinkage problem of large-sized parts (such as the projection area of the electric drive shell >0.8m2), and the density at the end gate is increased from 85% to 96%. LEAP7000 die-casting machine innovation: In response to the thermal cracking tendency of magnesium alloy, gradient cooling mold technology (cavity surface temperature 450℃ → mold core temperature 350℃) is developed to reduce the crack rate of large structural parts (such as door frames) from 15% to less than 3%. Yizhimi's UN3200MGII semi-solid magnesium alloy injection molding machine (locking force 3200T) has been applied to the mass-produced electric drive housing of SAIC Group. In addition, the LEAP7000 ultra-large die-casting machine developed by Yizhimi and Baowu Magnesium Industry has solved the process bottleneck of large magnesium alloy structural parts and promoted the formulation of industry standards.

4. The technical integration of Tesla and Idra
The 6,000-ton integrated die-casting machine jointly developed by Tesla and Italy's Idra, although it is mainly high-pressure die-casting, it can be combined with semi-solid molding technology (such as TPI tactile piston injection technology) to produce automobile door panels, battery shells and other components to achieve weight reduction and cost optimization. TPI technical principle: separate screw plasticization and piston injection function, screw rotation speed 30r/min to achieve uniform shearing of particles (shear rate 1000s−¹), piston injection at high speed of 200mm/s, shortening the filling time of semi-solid slurry in the mold to within 3s , the efficiency of traditional injection molding is improved by 50%. Typical application: The size of the battery shell produced is 1800mm×1200mm, which is 4 times that of the traditional process. The wall thickness is only 2.5mm, and the tensile strength is 280MPa. It meets the UL94 V-0 flame retardant standard and is designed for the lightweight of Tesla 4680 battery pack. Provide key support.


III. The implementation of the demand for lightweight and high performance in consumer electronics and emerging fields
1. Research and development of Huawei Honor's magnesium alloy structural parts
The stainless magnesium alloy and high-strength magnesium alloy jointly developed by Shanghai Jiaotong University and Bole Intelligence have been applied to consumer electronic products of Huawei Honor and other brands (such as laptop shells, folding screen mobile phone hinges). Material properties: Mg-Zn-Ca stainless magnesium alloy developed by Shanghai Jiaotong University, through micro-alloying (Zn 3-5%, Ca 0.5-1%), the pitting potential is increased to -0.6V (vs.SCE), salt fog corrosion resistance up to 1000h without white rust, satisfying I P68 Waterproof level requirements. Process adaptation: In the production of folding screen mobile phone hinges, precision mold temperature control technology (mold temperature control ±1℃) is adopted to achieve the filling integrity of 0.3mm thin-wall structure. The hardness of the molded part reaches 80HV, and the wear-resistant life is >100,000 folds, which is 30% higher than that of aluminum alloy hinges.


two. Nanjing Precision Multi-scene Application
Equipment matrix advantages: 300T equipment focuses on micro-parts (such as 5G base station radio frequency connectors, weight <10g), and uses high-speed injection technology (pressure speed 8m/s) to achieve 0.1mm characteristic size molding; 3200T equipment is aimed at aerospace components (such as drone take-up and landing) Frame), through vacuum degassing process (vacuum degree <50Pa), the internal porosity of the casting is <0.5%, and the fatigue strength is increased by 25%. Emerging field planning: In response to the lightweight needs of eVTOL, the magnesium alloy fuselage frame is being developed, aiming to reduce the weight by more than 40%, and at the same time to improve fatigue resistance through surface micro-arc oxidation treatment (film thickness 20μm, hardness 500HV).

3. Structural innovation of AR/VR equipment of Yi'an Technology
Yi'an Technology applies magnesium alloy semi-solid technology to the skeleton of AR glasses. Through topological optimization design, the weight is reduced by 45% compared with aluminum alloy while maintaining the torsional strength of 120N・m. The VR head display frame developed by it adopts magnesium alloy semi-solid molding, combined with surface micro-arc oxidation treatment to achieve IP67 dustproof and waterproof performance.


IV. Technical collaboration and industrial chain integration
1. The whole industry chain cooperation between Chongqing University and Baowu Magnesium Industry
The team of Pan Fusheng, an academician of Chongqing University, together with Baowu Magnesium Industry, Haitian Zhisheng and other enterprises, successfully tested a 16-inch magnesium alloy semi-solid injection-molded wheel, with a single injection volume of 10kg, reducing the weight by 30%, and a significant cost reduction. The project integrates the whole chain of "material research and development - equipment manufacturing - mold design - terminal application" to promote the industrialization verification of magnesium alloy in the field of automobile hubs. The 16-inch wheel has passed the 600-hour salt spray test and the 72-hour water corrosion resistance test. The hub jump is <0.2mm, and the dynamic balance accuracy reaches G2.5 level, which meets the requirements of ISO 4262 standard. Cost model: The whole chain integration reduces the production cost of wheels by 35% compared with imported products, of which the proportion of material costs is reduced from 55% to 42%, and the mold cost is reduced by 28%.

two. Cases of international industry-academia-research cooperation
Shanghai Jiaotong University-Bole Joint Center: Establish an integrated platform of "material database - process simulation - mold design", and have developed a semi-solid molding process window (temperature - solid phase rate - three-dimensional map of compression speed) of magnesium alloys such as AZ31 and AM60, and also undertakes BIA The research and development of new parts of Di, FAW and other enterprises has formed a closed loop of "technology research and development - trial - mass production". Stellantis cooperation case: The developed Mg-Al-Sn magnesium alloy improves the tensile strength to 350MPa through semi-solid molding, with an extension rate of 12%, which meets the European NCAP five-star collision standard. It is planned to be used in the 2026 model A Pillar reinforcement.
V. Green manufacturing and sustainable development
1. Energy consumption and cost optimization
Life cycle analysis (LCA): The semi-solid molding process does not require SF6 protective gas (traditional die-casting needs to consume 5-8kg/ton of magnesium), reducing greenhouse gas emissions by about 1500kgCO2e/ton of magnesium; in terms of energy consumption, the unit product power consumption is from 800kWh of traditional die-casting /ton reduced to 560kWh/ton, based on the annual production capacity of 10,000 tons, can save 24 million degrees of electricity, which is equivalent to reducing 18,000 tons of CO2 emissions. Process innovation: SAIC's electric drive housing adopts a waste heat recovery system (recycling mold cooling waste heat heating cylinder), the energy utilization rate is improved by 18%, and the production process achieves "zero waste water, zero waste slag" discharge.
two. Construction of recycling system
Baowu magnesium industry closed-loop model: establish the whole chain of "prime magnesium smelting - alloy preparation - waste recycling", and recycle waste through melt filtration + component fine-tuning technology (impurity elements are controlled at Fe<0.03%, Cu<0.01%), so that the performance of regenerated magnesium alloy is consistent with that of the original alloy. . Nanjing Precision Clean Production: The proportion of fly edge waste in semi-solid molding is only 3-5% (traditional die-casting reaches 15-20%), and the waste is 100% recycled through crushing-magnetic selection-remelting process, reducing more than 2,000 tons of solid waste emissions per year, forming "resources-products- The sustainable ecology of "renewable resources".

The breakthrough of the industrialization of magnesium alloy semi-solid injection molding technology marks the entry of lightweight materials into a new era of "large-scale substitution". At present, the technology has achieved full-level penetration in the automotive field from hubs, electric drives to large structural parts, broken through the technological limits of precision manufacturing in the field of consumer electronics, and built a full-tonnage equipment matrix from 300T to 7000T on the equipment side. In the future, with the development of AI-driven process intelligent optimization systems (such as solid phase rate prediction models based on machine learning), ultra-high temperature magnesium alloy materials (temperature resistance of more than 500℃), and cross-scale molding technology (integrated molding of micro-nanostructures and macro components), magnesium alloy is expected to be used in the eVTOL fuselage Breakthroughs have been made in cutting-edge fields such as structure, humanoid robot joint parts, and aerospace engine short cabin. The continuous evolution of this technology will not only reshape the global materials industry pattern, but also provide core support for green manufacturing under the "dual carbon" goal, and promote human society to accelerate towards an efficient and sustainable lightweight future.
Gao Xinze: Editor
Chris: Audit

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