Comparison of materials

Confronto con materiali

Pressure die casts of zinc alloys are competitive compared with many other materials for the production of large series of components, and they have led to many advantages in replacing small parts in materials such as aluminium, brass, assemblies in pressed sheet plate, magnesium and plastic.

 

Zamak die casting vs Aluminium die casting

• Improved precision
• Lower rake angles
• Thinner walls if necessary
• Longer mould Life
• Lower smelting costs (due to hot chamber smelting of zinc alloys)
• More finishing options
• Tensile strength and greater elongation
• Improved mechanical workability
• Non-sparking (suitable in environments with high explosive potential)

Most aluminium alloys for die casting are obtained starting from waste and their per unit volume cost is lower than zinc alloys; on the other hand, they can only be die cast using a cold chamber process which is less productive than the hot chamber process used to die cast zinc alloys. This means that the cost of a small part die cast from zinc is often lower than one die cast from aluminium. With zinc alloys it is also possible to melt the finished component, avoiding subsequent machining, and equipment life is much longer. For this reason, the price of die cast zinc alloy components is highly competitive. Furthermore, it is possible to apply any type of finishing (apart from vitreous enamel) on zamak components, while aluminium die casts are hostile to galvanic deposition.

 

Zamak die casting vs Brass processing

• Lower raw material costs
• Equivalent or lower tolerances obtainable
• Lower processing costs, including for simple shapes for turning
• Less processing scrap

Brass gives considerable freedom in the execution of processing on raw bars and highly reduced processing costs. However, even in this case, the processing costs arising from die casting of zinc alloys for the same small part are usually (although not always) lower and the cost of the raw material is significantly lower. For these reasons, the high equipment costs may also be convenient for a reduced number of parts.

 

Zamak die casting vs Pressed steel sheet assemblies

• Lower equipment costs
• Lower processing costs
• Improved design freedom

Steel components have very high rigidity and strength in relation to cost and also with respect to zamak die casts; on the other hand, design freedom is limited because more complex shapes can only be obtained by assembling multiple parts. However, die casting of zinc alloys permits the design of a small part with different already-assembled pieces and it is this feature that allows the die casting of zamak to compete with assembled steel. Another factor in favour of die casting of zinc alloys concerns processing costs and less equipment.

 

Zamak die casting vs Magnesium die casting

• Lower processing costs
• Greater tensile strength and elongation
• Improved corrosion resistance
• Lower rake angles
• Increased equipment life
• Greater rigidity
• Non-sparking (suitable in environments with high explosive potential)
• More finishing options

The properties of zamak die casts are superior to those of the magnesium from almost all points of view, apart from weight, which is why the tendency is to choose magnesium only when mass is a decisive factor.

 

Zamak die casting vs Plastic injection moulding

• Lower processing costs for thinner components
• More consistent properties
• Electric conductivity
• Significantly superior rigidity
• Much higher thermal conductivity
• EMI shielding

Plastic injection moulding is the most commonly used production process for complex shapes subject to low service loads. The main problem with placing pieces moulded in plastic under stress is their relatively low elastic modulus. However, increasing the wall section of a plastic piece also increases the moulding time and, consequently, also the processing cost. The greater the rigidity required, the more competitive a zamak die cast small part will be.

 

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