You can only make wise decisions on aluminum mold vs steel mold if you know their capabilities, cost, and compatibility with manufacturing scenarios. Let’s break down this comparison by discussing different aspects.
aluminum vs steel injection mold
Why Need Aluminum or Steel Mold for Injection Molding?
First, why do we need aluminum or steel molds? Well, molds are the cavities of the intended shape that define the contours of a molded part. Thus, we need these molds to manufacture our designed plastic components into exact geometry.
Although they have different capabilities, both have fundamental properties to facilitate the production of injection molded parts. Aluminum and steel alloys provide the strength, thermal conductivity, precision, and surface finish detail required to accept and shape molten plastic on solidification. Furthermore, aluminum and steel molds are corrosion-resistant, which makes them durable.
Overall, using these molds ensures the seamless injection molding of thermoplastics. That’s why we need them, even though they are preferable in distinct molding conditions.
Comparing Aluminum vs Steel Injection Mold
Aluminum and steel injection molds have differences in various aspects, such as thermal capability, durability, dimensional accuracy, surface finish of molded parts, production cycle time, etc.
aluminum injection mold
This comparison is often done as the soft tool vs the hard tool. Next, let’s elaborate on the main differences between them.
Thermal Properties
Thermal properties of mold materials directly impact the process efficiency as it determines how uniform heat will transfer within the mold and the time it takes to cool down. In this context, aluminum has almost five times more thermal conductivity (237 W/ m/K) than steel, which offers faster heat dissipation. Hence, aluminum molds heat and cool in much less time than steel molds.
The fast heat conduction ensures injected material fills the cavity uniformly because it allows liquid to flow across more distance. In comparison, steel cools slower, resulting in longer production cycle time. However, the longer cycle time gives more control over temperature and cooling rate.
Durability and Wear Resistance
The composition of carbon and other alloying elements provides steel superior strength, hardness, fatigue resistance, and thermal resistance. As a result, molds made from steel are highly wear and abrasion-resistant, can withstand injection molding pressure over time, and are more sustainable. They can repetitively go for molding cycles, up to millions.
In contrast, the quick heat flow in aluminum molds leads to rapid expansion and contraction of the material. Furthermore, it causes dimensional instability and misalignment in the molds over time. Additionally, an aluminum softer surface is more prone to scratching and denting. For all these reasons, molds made from aluminum are less durable and relatively less wear-resistant in comparison to steel vs aluminum injection molds. They are suitable to create a few hundred to ten thousand identical injection molding parts.
Oppervlakteafwerking
The smooth surface of mold cavities enhances the flowability and provides a quality finish to the molded parts. If we compare aluminum and steel injection molds, aluminum molds produce plastic parts with better finish. Although, it degrades over time and alters the surface roughness.
If you want SPI A-1 finish (Ra 0.012 – 0.025 µm), any mold can achieve that. Otherwise, the parts can be processed with further finish options like polishing and powder coating to achieve the desired aesthetic appearance.
Machinability and Modification Ease
Steels are comparatively more challenging to machine than aluminum because of their hardness and stiffness. On the other hand, aluminum is softer and quickly machinable, reducing mold production time and cost.
Next, the aluminum one is easy to modify between aluminum vs steel injection molds. This is again because of the hardness difference. Soft aluminum can be easily machined and modified, whereas steel mold modification requires more time and advanced machining setup.
Impact on Molding Cycle Time
The total cycle time of creating an injection molded part includes tool setup time, injection time, time to fill & form, and cooling time. Among these, mold cooling takes up to 50 to 80% of cycle time.
As aluminum has a higher heat dissipation rate, molds cool down in significantly less time than steel. So, they reduce the overall molding cycle time. Conversely, the low conductivity of and more complicated tooling increases the cycle time while molding with steel molds.
| Comparison Criteria | Aluminum Mold | Steel Mold |
| Thermal Properties | Five times higher thermal conductivity than steel mold and faster cooling rate. | Relatively low thermal conductivity and slower cooling. |
| Durability and Wear Resistance | Highly wear-resistant and can produce millions of parts. | Prone to wear and abrasion, and can be used for up to 10,000 parts. |
| Oppervlakteafwerking | Better smoothness | Less smooth surface |
| Machinability and Modification Ease | Excellent machinability and easy to modify and repair. | Steel is less machinable and modification is also complicated. |
| Impact on Molding Cycle Time | A higher cooling rate significantly reduces the cycle time. | Slower heal release increases the molding cycle. |
Advantages and Disadvantages of Aluminum and Steel Molds
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Materiaal eigenschappen
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3D-printen
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XTJ is een toonaangevende OEM-fabrikant die zich inzet voor het bieden van one-stop productieoplossingen van Aluminium 7075 Onderdelen van prototype tot productie. We zijn trots op het zijn van een ISO 9001 gecertificeerd systeem voor kwaliteitsmanagement en we zijn vastbesloten om waarde te creëren in elke klantrelatie. Dat doen we door samenwerking, innovatie, procesverbeteringen en uitzonderlijk vakmanschap.
