Ideal Materials for Mould Applications: MAX5® Mould Block and ALCA5® Cast Plate

PCP Aluminium

Moulding parts is a manufacturing process that is ubiquitous in industry. It is typified by requiring moulds made to fit a certain machine type or process type, depending on the parts to be manufactured. Moulds are made by machining various grades of alloys, including aluminium. Among the most important properties when machining moulds are high dimensional stability/accuracy, machinability, corrosion resistance, and light weight. Aluminium, and its alloy AA5083 in particular, is a very common material used for mould applications. It sufficiently meets all of the above-named property requirements and is very versatile in meeting more specific requirements through specific variations of the AA5083 alloy. We will now take a look at how and why AA5083 is well suited for mould applications.

There are numerous mould applications with different mechanisms which place emphases on one or more material properties over others for their successful operation. Some of these properties are non-negotiable across all mould types – for example, excellent dimensional stability and machinability - while others have wider tolerances and allowances. Aluminium alloys perform favourably for these applications and two products (produced from a modified version of the AA5083 alloy) MAX5® and ALCA5® are particularly suitable.

They have undergone precise heat treatment to be relieved of virtually all internal stresses after which they are milled/sawed to high levels of precision. Both MAX5® and ALCA5® have the same alloy constitution of 4 - 4.9% magnesium, 0.4% (max.) iron, 0.4 - 1% manganese, 0.4% silicon (max.), 0.25% zinc (max.), 0.15% titanium (max.), 0.15% zirconium (max.), 0.1% copper (max.), 0.05 - 0.25% chromium.

Why is AA5083 Aluminium Alloy Excellent for Mould Applications?

There are many moulding processes such as blow moulding, plastic injection moulding, panel moulding, compression moulding, thermoforming moulding, and more. Each of these types of moulding requires different critical mould-making properties of the materials they are constructed with to function optimally. AA5083 aluminium in the form of MAX5® and ALCA5® is very suitable for these mould applications for reasons which will be discussed below.

Machinability

Distortions during machining of moulds are unacceptable. For a material to be used for moulding applications, the tight tolerances that are expected for the mould and finished parts require machinability without distortion. This is a key feature of MAX5® and ALCA5®, which makes it excellent for applications for plastic moulds. MAX5® and ALCA5® can be easily cut into intricate shapes that involve cams and pins for more complicated mould designs.

Dimensional stability

MAX5® and ALCA5® are made from stress-relieved, primary AA5083 aluminium ingot and have excellent dimensional stability due to their extremely low internal residual stresses and zero recycled content. Unlike other materials that may warp or work-harden during machining or over time due to the effects of internal mechanical stresses, MAX5® and ALCA5® AA5083 remain flat and stable.

Recyclability

MAX5® and ALCA5® have excellent recyclability and re-manufacturability, which means that at the end of the lifespan of the material in one application, the aluminium alloy can be repurposed. For example, it can be melted and recast or machined for another application. Machine chips should also be easily scrapped and recycled.

Weldability

The design and building of moulds may require some parts of the mould base plates to be independently created first and then later welded together. Aluminium is typically difficult to weld – but welding is not an issue for AA5083. Both MAX5® and ALCA5® offer excellent weldability. Contact PCP Aluminium for further technical welding specifications.

Weight

Moulding operations may involve processes where the mould itself is part of a production line. In such applications, the weight of the mould would be a consideration. AA5083 aluminium, being three times as light as steel, is a good choice based on that fact alone, giving the production line more possibilities in design and handling. An example application is in packaging machinery which use blow moulds or automobile assemblies with robotics and panel moulds.

Surface finish and porosity

MAX5® and ALCA5® are produced to achieve a very high surface finish, with surface roughness as little as 0.4 μm for ALCA5® and 2.4 μm for MAX5®. Coupled with the fact that their alloy structure is practically pore-free, this makes them excellent for moulding processes that require extremely fine surface finishes.

Corrosion and chemical resistance

AA5083 aluminium has excellent corrosion and chemical resistance for mould applications as it doesn’t react with most plastics and other materials that are cast with it. This also allows moulding techniques that involve quenching media to be used. The integrity of the mould is intact after multiple mould operations without wearing off as a result of corrosion, which would have consequently required re-polishing and thus impacted the dimensional tolerances of the mould.

 

Table 1. Properties of ALCA5® and Max5®

 

ALCA5®

MAX5®

Density ρ

2.66 g/cm³ at 20 °C

2.66 g/cm³ at 20 °C

Surface roughness RMS

0.4 μm

25.4 μm (max)

Elastic modulus E

71 GPa at 20 °C

71 GPa at 20 °C

Elongation A

16 % at 20 °C

16 % at 20 °C

Hardness, Brinell HB

70 [-] at 20 °C

70 [-] at 20 °C

Tensile strength Rm

283 MPa at 20 °C

283 MPa at 20 °C

Yield strength YS

124 MPa at 20 °C

124 MPa at 20 °C

Coefficient of thermal expansion α

2.376E-5 1/K at 20 °C

2.376E-5 1/K at 20 °C

Thermal conductivity λ

120 W/(m·K) at 20 °C

120 W/(m·K) at 20 °C

Electrical conductivity σel

1.57E+7 S/m at 20 °C

1.57E+7 S/m at 20 °C

Specific Electrical conductivity

27 % IACS

27 % IACS

How can you take advantage of MAX5® and ALCA5®

The ALCA5® cast precision plate and the MAX5® mould block are registered trademarks of PCP Aluminium which produces them from the best aluminium ingots and raw materials. The MAX5® block can be produced in dimensions of up to 102” in width, 42.5” thickness and 290” in length. These dimensions are larger than required for most mould applications, so the MAX5® can be sawn to the exact required size to minimise wastage. The ALCA5® plate is available in thicknesses between 1/4” to 4” and in widths and lengths, up to 96.5” and 289” respectively.

Visit the PCP Aluminium supplier page for more information on their materials listed on Matmatch and to get in direct contact with them.

Article by PCP Aluminium

PCP Aluminium is a world-class company engaged in the manufacturing of aluminium precision cast plates and cast molding blocks.


Our high-quality products meet the highest market standards. Mainly used in the manufacturing industry, especially in automotive, marine and plastic manufacturing, our unique products have the dimensional accuracy and stability that will facilitate the achievement of your machining projects while minimizing the additional operations, such as slitting, milling, roughing and other operations commonly used in your everyday applications.