The aluminum extrusion process can be done by direct extrusion and indirect extrusion. The direct extrusion process (also is called forward extrusion) is the most common aluminum extrusion process for many aluminum extrusion manufacturers. But do you know about indirect extrusion (also is called backward extrusion, or reverse extrusion)? Do you know some extrusion products must be produced by indirect extrusion? Let’s know more about the indirect extrusion process.

What is indirect extrusion?

Normally, during extrusion billet is moved through the extrusion channel under pressure. During indirect extrusion processes, the die is held constant as the billet moves with the container. For this to happen successfully, a stem is applied. One of the stem’s properties is that it must be longer than the container moving with the die.

indirect extrusion


The length of the stem will determine how long the final length of the product being extruded will be. Therefore, manufacturers decide the shape of an extrusion product by cutting the same on the stem. This way, both the extruded Aluminum and stem will share the same length thus determining how long your Aluminum extruded product is.

For indirect extrusion to be complete, some requirements must be met. First, the billet must be preheated, although this is a requirement of all extrusion processes. This is then forwarded into the pressure chamber.

Again, both direct and indirect extrusion processes happen under pressure. The movement happens as a hollow plunger pushes the billet through a hollow die. At the end of the stem, there’s some blockage of sorts. This allows the billet to absorb pressure and travel back through the hollow die.

As this happens, the billet assumes the shape of the die. The extruded Aluminum product that leaves the extrusion unit assumes the shape of the die!

When making the decision about which extrusion process to choose, a lot is considered. The advantages of indirect extrusion are considered if one wants to settle for this process. The reverse is true.

Manufacturers explore other extrusion options if their benefits outdo the indirect extrusion process, or if the disadvantages of this option are way too many. On that note, let’s consider the advantages and disadvantages of indirect extrusion.

What Aluminum extrusion products are made by indirect extrusion?

The aluminum extrusion product is used to make specific products due to the nature of the process. Besides, some products can only be best produced using this extrusion option. Here are some of the products that can be produced using this option.

7075T6 aluminum

Making hollow 7075 aluminum extrusion products have been made possible through indirect extrusion.

seamless 7075 aluminum tube -

The seamless 7075 hollow tubes are produced by the indirect extrusion process.

7075T6 aluminum round bar-fonnov aluminium

The aluminum round bars (solid aluminum rods and extrusions) have been used to serve various purposes in different industries. The round bars are long-lasting and of great quality. They get these properties from the indirect extrusion process.

All the above are applications of this important product that has proven very useful in the extrusion world. It’s also affordable on most platforms and offers great value for money.

Advantages of the indirect extrusion

  1. Significant reduction in friction

During extrusion, a lot of heat and pressure are involved. It’s also important to note that Aluminum is not easily bendable and stretchable. Therefore, a lot of friction is likely to be experienced. Using indirect extrusion significantly reduces friction by 25-30%. This increases the quality of the final product by a huge margin.

Besides, friction reduces the size of the final extruded product. By reducing friction, you allow the process to give larger outputs. That may mean more money for manufacturing companies. Also, you enhance the extrusion speed as well as allow the production of smaller cross sections.

  1. Reduced cracks

Considering the properties of aluminum, it’s easier to crack under pressure and heat due to friction. Indirect extrusion reduces friction by up to 30%, therefore, you reduce the likelihood of your metal cracking. This means the production of better quality extruded products. Besides, you limit the amount of wastage occurring during the extrusion process.

  1. Reduced maintenance fee

Another benefit of indirect extrusion is the fact that you will have longer-lasting container liners. This is because of the reduced friction inside the extrusion container. For manufacturing companies, this is a big gain because they’ll be able to save maintenance costs that tend to reduce their profit margin.

For the consumer, a reduced cost means the manufacturer reduces the selling price as well. This gives greater value for money. Besides, the quality you purchase is also likely to increase.

  1. More flawless extrusion products

When you have a well-coursed container, it becomes less likely to have extrusions with defects. And that’s why indirect extrusion may be preferred sometimes. The process produces better products and that explains why some manufacturers opt for this option.

While there are many more advantages to this process, it also has some flaws that may prompt some manufacturers to think twice about it. Here are some of the disadvantages of indirect extrusion.

Disadvantages of indirect extrusion

  1. Cross section limitations

The size of the stem limits the cross-sectional area. But this is not a limitation when the goal is to make products with smaller cross-sectional areas.

  1. Affected aesthetics

Extrusion makes products, some of which require aesthetically appealing looks. Sometimes, there are impurities on the surface of the extruded products. This affects the surface’s final outlook and may have a bad impact on the product.

Direct VS Indirect extrusion. Which one is better?

At the end of the day, you don’t have to choose between the two options: direct extrusion or indirect extrusion.

Direct extrusion has many benefits including longer workpieces, operational flexibility, low cost per component, continuity, and easy product modification. If those benefits are what you’re searching for then direct extrusion is the better option. You can choose direct extrusion for many aluminum extrusion products.

On the other hand, indirect extrusion makes products with reduced friction, cracks, maintenance fee, and flawless ones. If you are working on a seamless extruded 7075 aluminum tube, the large size of aluminum round bars, aluminum rods, as well as shaped rod extrusions, then go ahead with indirect extrusion.

Manufacturers like FONNOV ALUMINUM continue to use these processes to make complex aluminum products for their esteemed clients satisfactorily. And that’s why you can have a try on us.


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