Полутвердое литье под давлением (SSDC) is an advanced metal-forming technology that bridges the gap between traditional casting and forging—redefining how high-performance metal parts are made. Unlike conventional die casting (which uses fully molten metal) или ковкость (which relies on solid metal deformation), SSDC leverages metal in a semi-solid state (50–90% solid fraction) to create parts with superior density, сила, and defect resistance. But what exactly makes this process unique? How does it work at a technical level? And why is it becoming a go-to for industries like automotive and aerospace? This article answers these questions with detailed insights, данные, и реальные приложения.
1. Основное определение & Принцип работы: The “Semi-Solid” Advantage
To understand SSDC, we first break down its fundamental concept and the science behind its performance.
А. What Is Semi-Solid Die Casting?
Semi-solid die casting is a process that:
- Treats metal (typically aluminum, магний, or zinc alloys) to a solid-liquid coexistence state during the early stages of solidification.
- Uses mechanical stirring, electromagnetic induction, or special cooling to break traditional dendritic (tree-like) metal structures into spherical solid particles suspended in a liquid metal matrix.
- Injects this semi-solid “slurry” or pre-formed semi-solid billets into a mold under controlled pressure (20–100MPa) to form parts—combining the flowability of liquid metal with the structural stability of solid metal.
Беременный. Key Scientific Principle: Non-Dendritic Microstructure
The success of SSDC lies in its ability to create a non-dendritic microstructure—a stark contrast to conventional casting:
| Microstructure Trait | Conventional Die Casting (Fully Molten) | Полутвердое литье под давлением |
| Structure Type | Dendritic (branched, interlocking grains) | Spherical (униформа, isolated solid particles) |
| Flow Behavior | Newtonian (flows like water; prone to turbulence) | Non-Newtonian (thick like toothpaste; flowability improves with shear force) |
| Solidification Shrinkage | Высокий (2–3% volume reduction; causes pores/voids) | Низкий (0.5–1% volume reduction; minimal defects) |
| Механическая прочность | Ниже (НАПРИМЕР., 200–250MPa tensile strength for aluminum) | Выше (250–350MPa tensile strength for aluminum) |
This spherical microstructure is the “secret” behind SSDC’s performance—it eliminates grain boundary weaknesses, reduces gas entrainment, and ensures uniform material properties.
2. Two Main Process Methods: Rheological vs. Thixotropic Casting
SSDC has two primary workflows, each optimized for different production needs. The table below compares their key features, преимущества, и идеальные варианты использования:
| Process Method | Основной рабочий процесс | Ключевые преимущества | Ограничения | Идеальные приложения |
| Rheological Casting | 1. Melt metal and cool to semi-solid state.2. Stir to form semi-solid slurry.3. Inject slurry directly into the mold (no secondary heating). | – No billet storage/handling; continuous production.- Более низкое использование энергии (avoids reheating).- Faster cycle time (30–60 seconds/part). | – Slurry has short shelf life (<30 минуты); requires on-site preparation.- Less flexible for small-batch runs. | Большое объем, стандартные детали: Automotive wheels, электромобиль (Эвихт) батарея, consumer electronics frames. |
| Thixotropic Casting | 1. Melt metal, stir to form semi-solid slurry, and cast into billets.2. Store billets at room temperature until needed.3. Reheat billets to semi-solid state (using induction heating).4. Inject into the mold. | – Billets have long shelf life (6–12 месяцев); flexible production scheduling.- Easier quality control (billets can be inspected before use).- Подходит для сложного, детали малого и среднего объема. | – Higher energy use (reheating step).- Longer cycle time (45–90 seconds/part). | Сложный, high-value parts: Аэрокосмические скобки, Компоненты медицинского устройства, automotive knuckles. |
3. 5 Ключевые преимущества: Why SSDC Outperforms Traditional Methods
Semi-solid die casting delivers tangible benefits that address pain points of conventional manufacturing. Below is a detailed breakdown of its most impactful advantages:
А. Superior Part Quality & Механические характеристики
- Плотность: SSDC parts have a density of ≥99.5% (против. 97–98% for conventional casting), eliminating pores and shrinkage defects. This makes them ideal for pressure-resistant parts like hydraulic valves or EV battery enclosures.
- Сила & Стойкость: The spherical microstructure boosts tensile strength by 15–30% and elongation by 50–100% (НАПРИМЕР., aluminum alloy parts reach 300MPa tensile strength vs. 220MPa for conventional casting).
Беременный. Reduced Defect Rates & Scrap Costs
- Conventional die casting has a scrap rate of 8–15% (due to pores, холодно закрывается, или усадка). SSDC cuts this to 2–5%—saving manufacturers \(10,000- )50,000 annually for mid-sized production runs (100,000 части/год).
В. Extended Mold Life
- SSDC uses lower pouring temperatures (НАПРИМЕР., 600–650°C for aluminum vs. 680–720°C for conventional casting). This reduces thermal shock to molds, extending their lifespan by 30–50% (от 50,000 shots to 75,000+ shots for aluminum molds).
Дюймовый. Improved Material Utilization
- SSDC’s low shrinkage (0.5–1%) eliminates the need for risers (extra metal used to feed shrinkage in conventional casting). This boosts material utilization from 70–80% to 90–95%—reducing raw material costs by \(2- )5 per kg for high-value alloys.
Эн. Versatile Post-Processing
- Unlike conventional casting (which often has hidden defects that fail heat treatment), SSDC parts can undergo T6 heat treatment, сварка, or precision machining without cracking. This makes them suitable for multi-step manufacturing of complex assemblies (НАПРИМЕР., automotive suspension components).
4. Типичные приложения: Industries Transformed by SSDC
Semi-solid die casting is not a niche technology—it’s already reshaping key industries by solving unmet needs for strength, легкий вес, и надежность.
| Промышленность | Ключевые приложения | SSDC Advantage Over Traditional Methods | Пример реального мира |
| Автомобиль | – ЭВ -аккумуляторные корпусы- Колеса- Steering knuckles- Компоненты передачи | – Легкий вес (aluminum parts reduce vehicle weight by 10–15%, boosting EV range).- Высокая ударная стойкость (critical for crash safety). | Tesla uses SSDC for Model Y rear subframes—cutting part count from 70 к 2 and reducing weight by 18kg. |
| Аэрокосмическая | – Двигатели кронштейны- Satellite structural parts- Компоненты шасси | – Высокое соотношение прочности к весу (meets aerospace standards like ASTM B928).- Low defect rates (критическая для критических деталей). | Boeing uses SSDC magnesium alloy brackets in 787 Dreamliner—reducing fuel consumption by 3% due to weight savings. |
| Медицинские устройства | – Хирургический инструмент ручки- Imaging equipment frames- Prosthetic components | – Биосовместимость (SSDC aluminum/titanium alloys meet ISO 10993 стандарты).- Точность (tolerance ±0.05mm for small parts). | Medtronic uses SSDC for surgical tool shafts—ensuring consistent performance in sterile environments. |
| Потребительская электроника | – Laptop/tablet frames- 5G antenna housings- Радиаторы | – Thin-walled capability (can produce parts with 1–2mm walls without defects).- Хорошая поверхностная отделка (Ra 1.6–3.2μm, reducing post-processing). | Apple uses SSDC for MacBook aluminum frames—improving durability while reducing weight by 12%. |
5. Yigu Technology’s Perspective on Semi-Solid Die Casting
В Yigu Technology, we see SSDC as a cornerstone of “next-generation manufacturing”—especially for the EV and aerospace industries. For our automotive clients, our rheological casting lines (equipped with real-time slurry quality monitoring) have reduced battery housing defect rates from 12% к <1.5%, meeting IP68 waterproof standards. For aerospace partners, our thixotropic casting process produces brackets with 99.8% плотность, passing 10,000-cycle fatigue tests.
We’re advancing two key innovations: 1) AI-driven slurry stirring (optimizes particle sphericity to >90%, boosting strength by 20%); 2) Hybrid SSDC-forging (combines SSDC’s shape flexibility with forging’s surface precision for ultra-high-performance parts). Our goal is to make SSDC more accessible—lowering equipment costs by 30% for mid-sized manufacturers and accelerating the shift to lightweight, sustainable metal parts.
Часто задаваемые вопросы
- Is semi-solid die casting only suitable for aluminum alloys?
No—SSDC works with a range of non-ferrous alloys, including magnesium (ideal for lightweight parts), цинк (для маленького, high-volume components), and even copper (Для теплостойких частей). Однако, it is less suitable for high-melting-point metals like steel (requires extreme temperatures to reach a semi-solid state).
- How does the cost of SSDC compare to conventional die casting?
SSDC has higher upfront equipment costs (≈ (200,000- )500,000 против. \(100,000- )250,000 for conventional casting lines). But for high-volume production (>50,000 части/год), lower scrap rates and material savings offset this—typically breaking even within 1–2 years. Для небольших партий, thixotropic casting (using pre-made billets) is more cost-effective than rheological casting.
- Can SSDC produce parts with complex shapes (НАПРИМЕР., подписаны, тонкие стены)?
Yes—SSDC’s semi-solid slurry flows smoothly into complex mold cavities without turbulence, making it ideal for parts with undercuts (using slider molds) или тонкие стены (1–2 мм). Например, we’ve produced EV battery housings with 1.5mm walls and integrated cooling channels—something conventional casting struggles to achieve without defects.