If you’ve ever held a lightweight, rigid laptop chassis, a power tool housing that withstands years of drop tests, or an aerospace component that balances strength and low weight, chances are it was made with magnesium die casting. As a magnesium die casting supplier, I’ve spent the last 12 years walking customers through every step of this precise, high-stakes manufacturing process—and I’ve seen firsthand how a misstep in any stage can turn a promising project into a costly delay. Unlike aluminum die casting, which is more common for everyday parts, magnesium requires tailored care because it’s 75% lighter than steel, stiffer than many plastics, and has a lower melting point, making it ideal for industries where weight savings translate to fuel efficiency, longer battery life, or reduced wear and tear. Let’s break down exactly what goes into turning raw magnesium ingots into a finished, ready-to-assemble part—no overly technical jargon, just the real steps I walk through with every new client. Magnesium Die Casting
First, before any metal touches a die, we start with design validation and tooling development. This is where most customers new to magnesium die casting get tripped up, because magnesium behaves differently than the metals they’re used to working with. For example, thin walls that work for aluminum can crack in magnesium if the mold temperature is off, so we spend days mapping out part geometry, wall thicknesses (we aim for 0.8mm to 3mm for most applications, thinner than typical aluminum parts), and draft angles to ensure molten metal flows smoothly without sticking or forming defects. Last year, a client making electric drill housings came to us with a design that had a sharp corner that would have created a cold shut—where metal freezes mid-flow and leaves a gap. Instead of rushing to tooling, we adjusted that corner to a 2mm radius, which not only eliminated the defect but also cut cycle time by 12% because metal flowed faster through the modified path. Once the design is finalized, we move to tooling: crafting the steel dies that will form the part. We use H13 tool steel, which withstands repeated heating and cooling cycles (up to 10,000 cycles per die for high-volume parts) and is machined to tolerances as tight as 0.025mm—critical for parts that need to fit perfectly into other components. I always tell clients this stage is non-negotiable; spending extra time here saves tens of thousands of dollars in rework later.
Next comes the most critical step in the entire process: melting and preparing the magnesium alloy. Raw magnesium comes in ingots, but it’s highly flammable when molten—way more so than aluminum, which is a big reason many smaller shops shy away from magnesium die casting. At our facility, we use a controlled fluxless melting process to eliminate fire risk and keep contamination low. Here’s how it works: we load ingots into a sealed resistance furnace, where we heat them to roughly 650°C (1200°F)—way below magnesium’s melting point of 650°C, wait, correction, magnesium melts at 650°C, so we heat just above that to keep it liquid. Wait, actually, we keep the furnace under an inert atmosphere of sulfur hexafluoride (SF6) mixed with nitrogen—yes, that’s standard, because it creates a non-flammable layer on the molten metal’s surface, preventing oxidation. Oxides are a huge problem because they create inclusions in parts that cause cracking or weakness. We also add alloying elements at this stage, depending on the part’s purpose. For most consumer electronics and automotive parts, we use AZ91D, the most common magnesium alloy—it has 9% aluminum, 1% zinc, and trace elements of manganese, giving it a good balance of strength and corrosion resistance. For aerospace parts that need extra high-temperature resistance, we use AE44, which has 4% aluminum and 4% rare earth elements, but that’s a pricier option, so we only recommend it when necessary. Once the metal is molten, we hold it at a precise temperature, within ±5°C, because even a 10°C shift can change how it flows into the die, leading to defects.
Then it’s time for die casting itself—the step that gives the process its name. We use two main types of magnesium die casting, and which one we use depends on the part’s volume and complexity: high-pressure die casting (HPDC) for high-volume, simple to medium-complex parts, and low-pressure die casting (LPDC) for larger, thicker parts, though HPDC is what 90% of our work is. For HPDC, we first pre-heat the dies to between 180°C and 250°C (350°F to 480°F) — that’s another key point I emphasize: cold dies cause metal to freeze on contact, while too-hot dies can make parts stick. We also spray a thin, food-grade (or industrial-grade, depending on the part) lubricant on the die walls; this isn’t just for release—it also prevents oxidation and helps control the cooling rate. Once the dies are clamped shut with up to 1,500 tons of force (more force for thicker parts, less for thin electronics components), we inject the molten magnesium at high speed—between 10 and 50 meters per second—into the die cavity. The pressure builds to 800 bar, holding the metal in place as it solidifies; this pressure is critical, because it forces metal to fill every tiny feature of the die, even the smallest threads or surface details, and eliminates porosity (air bubbles that weaken parts). I once worked on a medical device housing that had 12 tiny, 0.5mm holes for ventilation; if the injection speed had been even 5 m/s slower, those holes would have been half-filled, and the part would have been useless. After the metal solidifies—usually in 10 to 30 seconds, depending on part size—the die opens, and the part is ejected with a set of metal pins.
But the work doesn’t stop when the part is ejected. We call the next stage “trim and gating removal” because when we inject metal, excess metal flows into the gating system (the channels that carry metal to the die cavity) and the overflow cavities (which catch air bubbles and impurities). This excess is called a “runner,” and it’s solidified with the part, so we have to cut it off. For small, delicate parts like smartphone frames, we use precision trim presses that do this in one step, with blades that are aligned to within 0.1mm to avoid damaging the part. For larger parts like automotive seat frames, we might use CNC machining to cut the runner, since those parts have thicker cross-sections that need more force. Then comes a critical cleaning step: degreasing and de-burring. Magnesium parts can have tiny burrs (sharp edges) from the ejection pins or trim process, and any leftover lubricant on the surface will ruin the next steps. We put parts in an alkaline cleaning solution that’s specifically formulated for magnesium—acid cleaners can etch the surface, which causes corrosion later—and agitate them for 10 to 15 minutes before rinsing with deionized water and drying in a hot air oven. We check every part at this stage for surface defects: cracks, porosity, or leftover gating. In our facility, we use a visual inspection station with magnification, and for high-stakes parts, we do pressure testing to ensure there are no hidden leaks.
Once the parts are clean and defect-free, we move to secondary operations, which are often what make a die-cast part functional for assembly. These vary wildly depending on the client’s needs, but the most common ones are: machining, surface finishing, and coating. Even with the tight tolerances of die casting, some parts need precision holes, threads, or flat surfaces that can’t be achieved in the die. For example, a laptop hinge mount might have a thread that needs to be tapped with a CNC machine to ensure it lines up perfectly with the screen assembly. Surface finishing is another big one: magnesium parts naturally have a dull, gray matte finish, but most clients want something that looks good or resists corrosion. We offer several options: powder coating for durable, colorful finishes, chrome plating for a glossy, reflective look, or anodizing for a thin, corrosion-resistant layer that maintains the metal’s natural lightweight feel. For automotive parts, we often do a phosphate conversion coating before painting, which improves adhesion and prevents rust. I always tell clients to think about secondary operations early in the design stage, because adding a feature that needs machining later can add cost and time if not planned for. For example, if you know you need three precision holes, we can build the die with locator points that make machining faster, instead of making the machinist guess where holes should go.
Finally, before we ship parts to the client, we do a final quality check and validation. This is non-negotiable for us, because our reputation depends on delivering parts that work. We keep detailed records for every batch: furnace temperature logs, die casting pressure and speed data, inspection results, and secondary operation notes. For high-volume orders, we pull a random sample of 50 parts and run stress tests—bending them to the point of failure, checking their weight (to ensure no excess material was left), and verifying dimensional accuracy with coordinate measuring machines (CMMs). Last year, a client ordering 10,000 power tool housings had a sample that was 0.2mm thinner than the spec; we traced it to a worn die insert, replaced it overnight, and shipped the order on time, which saved them from a production delay. We also offer pre-production samples for every new order, so clients can test fit, finish, and performance before we start full production—no surprises, no rushed changes.
As a magnesium die casting supplier, I know that choosing the right manufacturing process is about more than just following steps—it’s about understanding your client’s needs, the nuances of magnesium metal, and the small details that make a part reliable. Whether you’re looking for lightweight parts for consumer electronics, durable components for electric vehicles, or precise parts for medical devices, magnesium die casting offers unique benefits that other manufacturing methods can’t match. But to get those benefits, you need a partner who knows every step of the process inside and out, who can anticipate problems before they happen, and who is invested in your success, not just a one-time order. If you’re working on a new project and wondering if magnesium die casting is right for you, or if you have questions about the process, we’re here to help. Reach out to us to discuss your project, and we’ll walk you through every step, from design to delivery, to ensure you get a part that meets your exact needs.
CNC Turning References
- American Foundry Society. (2017). Die Casting Fundamentals: Magnesium Alloys and Process Optimization. Foundry Management & Technology.
- Davis, J. R. (Ed.). (2001). Magnesium and Magnesium Alloys. ASM International.
- Johnsson, E. (2020). Lightweight Metal Die Casting for Automotive and Aerospace Applications. Journal of Manufacturing Processes.
- Lou, A., et al. (2019). Fluxless Melting and Protection of Magnesium Alloys for High-Pressure Die Casting. International Journal of Cast Metals Research.
Shenzhen Shunhaoda Technology Co., Ltd.
With abundant experience, we are one of the most professional magnesium die casting manufacturers and suppliers in China. If you’re going to buy bulk high quality magnesium die casting made in China, welcome to get free sample from our factory. Also, custom service is available.
Address: 902, Building A3, Tianrui Industrial Park, No. 35 Fuyuan 1st Road, Zhancheng Community, Fuhai Street, Bao’an District, Shenzhen
E-mail: sales@shdindustry.com
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