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PRIMARY PROCESSES

High-pressure aluminium injection casting

At STAC we are specialists in the manufacture of injection cast aluminium parts and we accompany our customers from conception through to the mass production of the desired part.

What is Part design FAQs Comprehensive solution

What is Aluminium Injection?

High pressure aluminium injection is a process used in the casting industry to manufacture aluminium parts with high precision and quality. HPDC (High-Pressure Die Casting)

In this process, aluminium is melted at 700°C and injected under high pressure into a special steel mould.

Inside this mould the negative of the piece called the “cavity” is engraved.

The high pressure allows the liquid aluminium to completely fill the mould cavity and acquire the desired details and characteristics.

Advantages of Aluminium injection manufacturing

High pressure aluminium injection offers several advantages compared to other manufacturing processes of aluminium parts such as gravity casting or machining parts from an aluminium block:

It allows the production of complex parts with thin walls, fine details and smooth surfaces.

In addition, the process is fast and efficient, which makes it suitable for mass production.

The resulting parts are lightweight, resistant and have superior mechanical properties to those made by gravity casting.

Sectors which use Aluminium injection

This method is used in a wide range of industries, such as automotive, aerospace, electronics and construction, to manufacture components such as engine casings, structural parts, transmission components, pump housing, among others.

At STAC we are specialists in this process and we accompany our customers from the initial idea to the final product.

Do you want to know how?

Design of injected aluminium parts

STAC has a team of design and industrialization engineers who collaborate from the outset with our customers to advise them in this primary phase.

The design of the parts has to consider the whole manufacturing process and the end use of the part.

These are some aspects to consider in the design of aluminium parts.

If you want to know more about any of the points, please contact us.

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Selection of the type of aluminium alloy

There are various aluminium alloys with specific properties. You must select the most suitable alloy for your application, considering factors such as strength, ductility, corrosion resistance, thermal conductivity, among others.

Design of geometry and thicknesses

The design of part geometry and wall thicknesses is crucial. You should avoid sharp transitions, sharp corners, and areas with too thin cross sections, as they can cause problems during the injection process and weaken the final part. It is also very important to define a suitable mould release angle.

Rounding of corners and edges

It is advisable to round the corners and edges of the piece, which helps reduce concentrated stress and improves strength and structural integrity.

Shrinkage considerations

During cooling, the aluminium contracts, so the shrinkage must be taken into account and the part designed in a way that minimizes negative effects. This involves providing enough clearance and allowing uniform contraction in all directions.

Proper location of injection points

Injection points are the places where aluminium is injected into the mould. They must be strategically placed to allow a uniform and complete flow of the molten metal into the entire mould cavity, avoiding dead spots and areas with filling problems.

Machining and finish considerations

If it is necessary to machine or apply a finish after injection, the part must be designed taking these operations into account. We consider the required tolerances, and how the finishes will affect the final appearance of the piece.

Frequently asked questions about aluminium injection

What is the best aluminium alloy for my project?

The pressure injection process requires alloys to have high fluidity, therefore only some of the aluminium alloys are suitable for manufacturing parts using this process.

Here are some of the main alloys used:

Aluminium alloy EN AC-46000 (AlSi9Cu3): This is a very versatile aluminium alloy and widely used in die casting. It has good fluidity, excellent corrosion resistance and high tensile strength. It is used in automotive, electronic and construction applications, such as motor housings, electrical components and support structures.
Aluminium alloy EN AC-46100 (AlSi12Cu): This alloy has a higher strength than EN AC-46000, making it suitable for applications requiring greater rigidity and mechanical strength. It is used in structural parts, transmission components and other applications where increased load and fatigue resistance are required.
Aluminium Alloy EN AC-46200 (AlSi10Mg): This alloy has excellent fluidity and surface finish characteristics. It is ideal for parts that require high precision and an aesthetic finish, such as electronic device housings, lighting parts and furniture components.
Aluminium alloy EN AC-44300 (AlSi12): This alloy has a good combination of fluidity, mechanical strength and corrosion resistance. It is widely used in the automotive industry for parts such as gearboxes, engine mounts, intake manifolds and other structural components.

For the correct definition of the alloy it is necessary to know the final use of the part, its surface finishes, the corrosion resistance requirements, the minimum and maximum thicknesses that the piece should have, … and many more things.

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The importance of the mould in aluminium injection

Remember that aluminium enters the injection mould at about 700ºC. At this temperature most steels lose their mechanical characteristics, because the heat modifies their internal structure.

That is why aluminium injection moulds have to be manufactured with steels for high-temperature work, and these are very special and very expensive. Before entering service and while being machined, they have to be subjected to various, highly-controlled heat treatments, so that their characteristics are optimal.

At STAC we have a tooling manufacturing department that is responsible for the design and manufacture of the moulds and their maintenance throughout their service life.

Some of the most important features to consider are:

Materials for the different parts of the mould: These materials must be sufficiently strong and durable to withstand the high pressures and temperatures of the injection process.
Moulding plates: The mould consists of a cavity and a core that define the shape of the part to be injected. These parts must be precise and have a high quality surface finish to ensure reproducibility and quality of the parts.
Cooling system: The aluminium injection mould must have an efficient cooling system to control the mould temperature during the process. This helps ensure proper solidification of the aluminium and an efficient production cycle.
Feed channels and overflows: The mould must have feed channels to allow the entry of the melted aluminium into the mould cavity. In addition, overflow areas are required at the perimeter of the mould to assist in the evacuation of air and impurities during the injection process.
Wear resistance: Since cast aluminium can exert significant pressures and forces on the mould, it is essential that the mould has adequate wear resistance and that interchangeable inserts are considered for the weaker parts of the tooling. This ensures long mould life and consistent part quality.

Aluminium moulds are perhaps the most technical tooling that we manufacture and the ones with the most critical maintenance.

STAC guarantees its customers the mould during the life of the tooling.

If you want to know more about this point, we help you. Contact us.

The importance of the machines in the aluminium injection process

To manufacture injected aluminium parts with the highest quality, our machines have the following characteristics:

High pressure and closing force: the machine must be able to generate and maintain high injection pressure to ensure proper filling and compacting of aluminium in the mould. In addition, it must have enough closing force to keep the mould safely sealed during the process.
Precise temperature control: the machine must have a precise temperature control system to ensure that the cast aluminium maintains the right temperature throughout the injection process, from smelting to injection time. This helps to avoid problems such as premature cooling or thermal imbalances that may affect the quality of the part.
High precision injection and dosing system: the injection and dosing system must allows precise control of the volume and injection rate of the melted aluminium into the mould. This ensures a uniform distribution of the material and avoids problems such as porosity or filling defects.
Injection pressure and speed control: the machine must have sophisticated controls that allow precise adjustment and control of injection pressure and speed. This is essential to adapt to the specific characteristics of aluminium and part design, thus ensuring optimal injection and minimizing defects.
Monitoring and logging capability: It is important that the machine has monitoring and data logging capabilities to allow detailed tracking of process parameters such as temperature, pressure, speed, times, among others. This facilitates the identification of potential problems and contributes to the continuous improvement of the manufacturing process.
Gas extraction system: Since aluminium injection can generate gases and bubbles during mould filling, the machine must have an efficient gas extraction system. This helps to minimize porosity and improve the quality of parts.
Robustness and stability: The machine must be robust and stable to withstand the high pressures and temperatures of the aluminium injection process. This includes a solid structure, high-strength components and reliable clamping and closing systems.
Safety: Our machines are fully robotised so that no worker comes into contact with the smelted aluminium.

If you want to know more about our aluminium injection capabilities, please contact us.

Comprehensive solution for manufacturing injected aluminium parts

Our comprehensive approach means we take care of every stage of the manufacturing process of injected aluminium parts, ensuring quality and efficiency at every step.

Below, we summarize the main services we offer.

Design

We have an experienced team of engineers and designers who will work closely with you to understand your requirements and turn your ideas into functional designs. We use advanced design tools and optimization techniques to ensure design viability and efficiency of your injected aluminium parts.

Prototypes

Before moving to large-scale manufacturing, we can provide prototypes of parts so you can evaluate their functionality and perform tests. This allows you to make adjustments and improvements before moving on to production.

Design and manufacture the mould

We have a wealth of experience in the design and manufacture of high quality moulds for aluminium injection. Our team of experts will ensure that the mould meets your exact specifications and requirements, optimizing the efficiency and quality of the injection process.

Manufacture of the parts

We use high pressure aluminium injection technology to manufacture quality parts with precision. Our advanced machinery and highly trained technical team allow us to produce parts with precise finishes and tolerances.

Machining processes

If necessary, we can perform additional machining operations, such as drilling, milling, turning or threading, to obtain the final dimensions and required shape of the parts.

Assembly

If required, we perform the assembly of the aluminium parts with other components, using bonding methods such as welding, threading, riveting or adhesion.

Finishing and lacquering processes

We also take care of the surface finishing processes of the parts, including polishing, sanding, blasting, anodizing, or painted or lacquered coatings, according to your specifications and aesthetic needs.

Quality Control

Our commitment to quality is fundamental. We perform rigorous quality controls at all stages of the manufacturing process, using advanced inspection and testing technologies to ensure parts meet the highest standards.

Flexible delivery

We adapt to your needs and deliver the finished products where you indicate. We make sure the parts are properly packaged and protected to ensure safe and timely delivery.

At STAC, we want to be your comprehensive supplier of injected aluminium parts.

We want to provide you with a comprehensive service and we take care of the entire process, from the initial design to the final delivery of the finished product where you request it.

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Our priority is to help the customer achieve their goals

At STAC, we are committed to excellence and customer satisfaction.

We are ready to work closely with you and meet your specific requirements.

Don’t hesitate to contact us to discuss your projects and how we can help you achieve your goals.

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Post-aluminium Injection processes

After the aluminium injection process, it is common to perform a series of subsequent processes to obtain the final parts with the desired characteristics.

The most common post-casting manufacturing processes are the following:

Deburring

It consists of removing burrs, sharp edges or unwanted protrusions from the moulded piece. This can be done by manual or mechanical methods, or using specialized machinery.

Machining

If necessary, we can perform additional machining operations, such as drilling, milling, turning or tapping, to obtain the final dimensions and required shape of the parts.

Mechanical surface treatments

To improve the appearance and protection of the part, various surface finishing techniques can be performed. These include vibrating, polishing, sanding, blasting , etc.

Assembly with other stamped, machined or injection-moulded parts

It is common to use processes and joining technologies for assembly between parts e.g. riveting.

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