Die Casting Vs. Metal Extrusion

Die cast parts

While die casting may be the most modern and popular form of metal shaping for manufacturing parts, there are many others to consider. It can be helpful to know about a variety of metal shaping methods to best determine what process is right for you, your parts and your business. 

Metal forming, shaping and casting are all production processes valuable to manufacturers. Depending on the metal you use and your desired outcome, forming can be accomplished in several different ways. In many cases, you will use molten metal and a cast or mold — a machine injects the molten metal into the cast so it takes on and holds the desired shape once it cools.

Other metal forming processes include forging, stamping and metal extrusion. Understanding the basic mechanics of each and its advantages will help you determine which is suitable for your operations. While metal extrusion is not appropriate for as many metal parts manufacturing applications as other metal-shaping methods, such as die casting, it’s still helpful to know what it is and how it works.

How Metal Extrusion Works vs. Die Casting

Knowing when to use metal extrusion versus die casting will often come down to the actual process involved and how it fits the application. Each version of the metal shaping process follows its own specific steps.

Die Casting Process

Die casting is a simple and modern way to create consistent, quality metal parts at high volume and low cost. Die casting employs aluminum, zinc or copper alloy, melting the metal and injecting it into a closed die in the shape of the parts you want to produce. The process subjects the metal to high pressure as it cools, resulting in a consistent and durable shape when completed. The five general steps to die casting are as follows:

  1. Clamping: The die must be thoroughly cleaned and lubricated before you can use it. You then clamp the two sides of the die together with high pressure.
  2. Injection: Molten metal is transferred to a chamber, then injected into the die.
  3. Cooling: The die with the injected metal remains clamped until the material has cooled enough to solidify.
  4. Ejection: After the metal is sufficiently cool, the caster unclamps the die halves and removes the product from the cast.
  5. Trimming: With the part free, extra metal inside the runner and sprue need to be removed right away via trimming.

Industries where die casting is common include:

  • Automotive
  • Household appliances
  • Aerospace
  • Electronics
  • Machinery
  • Furniture
  • Power tools
  • Decorative finishes
  • Toys

Metal Extrusion Process

Metal extrusion is a particular type of metal shaping. While die casting can be used to create just about any shape, metal extrusion is for long, straight parts like L-shapes, T-shapes, tubes and rectangular shapes.

The process of extrusion works by squeezing metal into the die using a hydraulic or mechanical press. The die has a wear-resistant material allowing it to handle high radial loads. This method is very effective for shaping without tearing the metal. Extrusion can be done cold, at room temperature, or hot – up to three-quarters of the metal melting point. 

Most parts created through metal extrusion use a cold process, which has no oxidation and allows for a good surface finish.

Pros and Cons of Metal Extrusion

You can use metal extrusion for specific types of part creation. Parts without uniform cross-sections are not good candidates for metal extrusion. There also tend to be size limitations for the parts you can make.

You may opt for metal extrusion over die casting when you have the right candidate. Tooling costs are usually lower and certain alloys, like magnesium and zinc, respond to the metal extrusion process with similar strength and stiffness as die cast parts but with higher ductility. 

Extruded parts will have a smoother surface, meaning no additional deburring or other measures are required. You can also make several metal extrusion molds quickly and efficiently, making this process viable for businesses with short production runs.

Metal extrusion is a popular process for the construction, agriculture, HVAC, aircraft and automotive industries because of the versatility and specificity of the products.

Pros and Cons of Die Casting

Die cast parts have greater stiffness and often do not require secondary finishing processes. Die casting is also a viable choice for products requiring unique shapes — once you create the die for the shape, you can reuse it repeatedly for many cycles. Additionally, die casting typically allows for larger products compared to metal extrusion.

One disadvantage of using die casting is the chance that air could be trapped inside the die, causing porosity in the part. Time constraints may represent an issue as well — many dies can take an extended period to prepare, meaning that production cannot begin immediately. Finally, die casting does come with weight limits, which is not always ideal depending on your application.

Given the differences between die casting and metal extrusion and the pros and cons of each, die casting is the way to go if you have a high-volume production run of more complex shapes, while the ease and quick setup of metal extrusion make it ideal for shorter runs of simple parts. 

Die Casting for Your Metal Part Needs

In the many cases where die casting is your best option, Premier Die Casting is the company to call. Premier has supplied high-quality metal parts for over 70 years, using state-of-the-art machinery and the most effective die casting processes. 

Premier has a system of automated process monitoring which, combined with expert staff, allows easy detection and correction of process issues and out-of-control variables. Premier Die Casting Company also has a licensed vacuum system for the highest-quality surface finish and casting and mold integrity. 

Whether you need hospital equipment, firearm trigger guards, bullet light fixtures or a wide variety of other parts, Premier can produce them quickly and at a low cost. To learn more about how die casting can enhance and improve your business, contact Premier Die Casting today.


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