A Complete Guide to Die Casting Process

Among the most popular fabrication techniques for making different parts is die casting. This is a systematic process that involves making a tooling system, choosing the right material and following a well-defined process.

By doing so, you can make intricate parts, with tight tolerance in critical applications like the aerospace industry.

In this guide, we will explore every critical information about die casting process:

What is Die Casting?

Die casting is a metal fabrication technique where you use specialized tooling system to inject molten material into a premade tooling design.

It is this tooling system that has a cavity, replicating the final part you want to fabricate. Furthermore, the die is mainly made hardened steel and it is also reusable.

Key Steps in Die Casting Process

Diecasting process involves series of processes, whose end result is a part that matches your technical drawing. That is, in terms or dimension, overall look and appearance.

In short, die casting involves – designing part and mold, preparing tooling (mold), melting material and forcing into the mold, allowing die cast part to cool, ejecting the part, and quality inspection.

Let’s discuss each process:

Step 1: Part Design & Mold Design

Note: Even before you choose die casting to fabricate parts, it is important to conduct cost analysis. As a general rule, die casting makes economic sense for high volume production.

This is mainly attributed to the high initial tooling costs. That is, the cost of making die casting mold.

For high-volume production, die casting is cost-effective and efficient.

With that in mind, the first process in the die casting is design stage. Remember, the die casting mold will depend on the type of parts you wish to fabricate.

Therefore, you must design the parts you want to make, before designing the mold.

Part Design

At this juncture, you must start by optimizing the parts you want to die cast through design for manufacturability (DFM). You engineers should use any simulating software to optimize part designs.

You can use AutoCAD, alongside 3D modeling, SolidWorks, Autodesk Fusion 360 and Autodesk Inventor, together with other simulation software such as MAGMASOFT.

Once you are satisfied with the design of parts to die cast, the next step will be mold design and fabrication.

During the component design, you must pay attention to the following:

• If possible, wall thickness should be consistent
• Always reduce weight and wall thickness
• Maintain draft angle at about 0.5º for die casting zinc parts and 1º to 5º for die casting aluminum
• Tolerance for die casting zinc can range from ±0.001 to ±0.002 inches while that for aluminum can be ±0.002 to ±0.004 inches.

Die Casting Mold Design and Fabrication

The die casting mold is a replica of the final product you want to fabricate. It is for this reason that it is usually referred to as the tooling system.

Remember, mold design is a critical part, that will determine the quality and usefulness of the final product.

During the die casting mold design and fabrication, it is important to pay attention to the following:

• Die casting mold material – Hot worked tool steels like H13, 8407 or SKD61, alloy structural steels like 30CrMnSi or 40Cr, high copper alloys like AMPCOLOY 940 and aluminum are common materials. In most cases, the material you want to die cast, lifespan of the mold and die casting technique will determine the tooling system material.
• Die cast mold parameters – Your mold design must take into account draft angles, fillets, radii, wall thickness, bosses, ribs, parting line, gating system, cooling system, venting system, and ejection mechanism.

Once you have the mold design ready, you can go ahead to fabricate the die cast mold.

With the advancement in technology, precision CNC machining has proved to be cost effective and viable option to fabricate molds. CNC machining may involve many operations including high-speed CNC milling, EDM and polishing.

Once the mold is ready, inspect and produce prototypes before the actual and mass die casting process begins. This is a critical stage that will help you reduce the cost of die casting.

Step 2: Choose Die Casting Material

Choosing die casting material is critical in ensuring you get high quality parts. As a guideline there are certain standards that define the chemical properties and specifications for die casting alloys.

Some of the most popular industry standards include:

• ASTM B58 for aluminum allot die casting
• ASTM B86 for zinc and zinc-aluminum alloy die casting
• ASTM B94 for magnesium alloy die casting

Of course, if you are targeting the American market, you must be conversant with the North America Die Casting Association(NADCA) standards and best practices.

This way, you will produce high quality parts.

Remember, most failures in die casting aren’t from bad machines or poor operators, but from materials choices made. Pay attention to whether the part needs high strength, corrosion resistance, thermal, and electrical conductivity.

Lightweight alloys like magnesium and aluminum are favored in automotive and aerospace applications; therefore, also put this into consideration.

Let’s summarize the metals alloys for die casting on the table below:

Therefore, choose die casting material according to your unique applications requirements

Step 3: Melting & Preparation

At this point, you will choose high quality material for die casting.

Here, it’s about controlling temperature, chemistry, and cleanliness with surgical precision. When melting, your furnace choice directly affects melt quality. You should ensure its does not contaminate your material.

Remember, each alloy has a specific melting and casting temperature window, and you must stay within it. If the melt is too hot, it causes oxidation and if it is too cold incomplete filling and cold shuts will occur

During metal preparation, the molten metal must be clean, degassed, and chemically balanced before injection. In metals like magnesium, silicon, or copper, the melt’s composition must be fine-tuned by adding master alloys to restore lost elements during melting.

Continue skimming to remove slags and dross. Then transfer to a holding furnace to maintain casting temperature before injection.

Step 4: Injecting Molten Material into the Die Cavity

This happens in milliseconds, under extreme pressure, and if you mishandle it, you’ll end up with defects, wasted alloy, and a damaged die.

The process involves forcing the molten metal into the die cavity at high speed and pressure, ensuring the mold is completely filled before solidification begins.

This will determine dimensional accuracy, surface finish, internal soundness, and cycle time.

High-Pressure Die Casting

In high-pressure die casting, you will inject your molten metal into a hardened steel mold at high pressure and speed.  The pressure can range from 1,500 and 25,400 psi.

Maintain the pressure until the metal solidifies, produces a dense, dimensionally accurate part with excellent surface finish and minimal machining requirements.

Low-pressure Die Casting

Here it’s all about quality and durability. You will push your molten metal upward into a closed die cavity using low gas pressure.

Gravity Die Casting

You will pour your molten metal into a preheated metallic die under the force of gravity. There is no pressure needed, no vacuum, just controlled flow.

Step 5: Die Cast Part Cooling and Ejection

After molten metal is injected into the die cavity, the next step is controlled cooling and solidification, followed by ejection of the finished casting.

These steps determine dimensional accuracy, surface integrity, and die life.

Step 6: Trimming and Finishing

After ejection, your die-cast part might have excess metal attached from overflows, vents, runners, and gates.

Trimming will remove these unwanted materials, and finishing will refine the surface and correct dimensional tolerances.

Step 7: Quality Inspection

This is the final step in the die casting process. You will have to verify whether each die-cast part meets the dimensional, structural, and visual requirements defined in design specifications and industry standards.

Tips to Reduce Cost of Die Casting

For many product designers, injection molding costs is a critical factor right from DFM. Here is a quick checklist that will help you reduce the cost of injection molding process:

• Reduce weight and wall thickness where possible
• Only opt for tight tolerance when necessary
• Optimize part design
• Choose the right die casting alloys
• Adopt a suitable die casting technique
• Maintain die casting mold to increase service lifespan of tooling system
• Reduce cycle time without compromising quality
• Use proper gating and venting design
• Optimize proper tooling design
• Let trained and experienced experts handle die casting
• Choose die casting for high volume part products
• Make prototypes before mass production to test die cast parts

Example of Die Cast Parts

Get started with your Die Cast Parts at KDM

When it comes to die casting parts, KDM remains the leading factory in China. KDM handles every stage in-house from part design and mold fabrication to casting, finishing, and inspection, making them end-to-end manufacturing expertise.

At KDM, we operates both hot and cold chamber die casting machines, capable of handling various types of metals.KDM has a scalable production capacity, they will scale your project without compromising consistency or delivery timelines.

Conclusion

Die casting is a precision manufacturing system that is built for speed, accuracy, and consistency. When you do it right, it delivers complex or high-quality components with tight tolerances and smooth finishes at a pace on other casting methods can match.

FAQs

What are the Advantages of Die Casting Process?

Die casting delivers tight tolerances without secondary machining.

They can produce intricate, near-net-shape parts with wall thicknesses as low as 0.5 mm. Additionally, you also get excellent finishes and high volume production.

Furthermore, die-cast parts exhibit high density and excellent mechanical strength with porosity.

Can you Achieve Tight Tolerance in Die Casting?

Yes. However, you can achieve tight tolerances in die casting, but not for free and not infinitely tight.

How do you Choose Die Casting Machine?

Choose a die casting machine that;

• Determines the Required Clamping Force
• Match to the type of Material
• Ensure the shot sleeve and plunger can inject the exact amount of molten metal needed
• The die must fit physically within the machine’s platens and between tie bars, with room for opening and ejection.

What is the difference between sand casting and die casting?

Sand casting is for low-volume, high-flexibility production, including prototypes, large components, or parts with complex cores that would be too costly to machine in a die.

Die casting is for high-volume, high-precision manufacturing when part quality, consistency, and speed justify the tooling investment.

Which is the easiest material to Die Cast?

Zinc is the easiest material to die cast.

Which die-casting companies in China are trustworthy?

Sunrise-Metal. Sunrise is a die-casting company with 15+ years of experience, specializing in aluminum die casting. Sunrise’s manufacturing capabilities encompass the entire die-casting process, including rapid prototyping, mold design, die casting, CNC machining, and surface treatment. Due to their high precision, low porosity (below 1%), and corrosion resistance, Sunrise’s die-cast components are particularly favored in industries such as medical, marine, and automotive.

EMP Tech is a global manufacturer of precision aluminum die casting products with over 30 years of experience in R&D, manufacturing, and CNC machining. We serve leading automotive, EV, telecom, and industrial companies worldwide. From die casting and machining to finishing and testing, all processes are completed in-house. With 350T–3050T machines, 40-day tooling, and 335k parts monthly capacity, EMP ensures fast and scalable production. Certified to ISO 9001, IATF 16949, and ISO 14001, we deliver OEM-grade quality, optimized for cost, weight, and performance.