S4L Diesel Used Engine Blocks For Excavator E304 Water Cooling
|Car name: Engine cylinder block|
|Model Number: S4L|
|Cylinder stroke: 87|
|Work Form: Turbo|
|valve: 8 valve|
|Cooling: Water cooling|
Criteria for alloy selection
Choosing the alloy requires the consideration of various criteria. Aluminium foundry alloys used in the production of such complex cast parts as engine blocks must meet a combination of requirements which include low cost, excellent castability, good machinability, and moderate strength at elevated temperatures.
The strength level of the alloy determines for example the applicable wall thicknesses and other design aspects. Thus it is most relevant define the alloy already in the first development phase of an engine block. Generally the selection of the alloy is a compromise. High strength casting alloys would be the preferred option, but they have also drawbacks such as higher cost (e.g. AlSi7Mg due to its lower limits for impurity elements), poor castability (e.g. AlCu4Ti) and insufficient high temperature performance.
For economic and technical reasons, almost all aluminium engine blocks are produced using alloys based on recycled aluminium (AlSi8Cu3, AlSi6Cu4). However, new requirements for an increased ductility could require the use of alloys with a reduced impurity content closer to the composition of primary casting alloys.
Castability is generally improved with increasing silicon content. On the other hand, copper additions which are needed for high temperature strength have a negative effect on the feeding behaviour. When the high pressure die casting process is applied, alloys with a certain iron and/or manganese content are necessary to prevent molten metal sticking to the die. But iron additions also reduce the mechanical properties of the cast component.
Other alloy specification aspects
In some cases, other requirements may be more important selection criteria than cost and castability. In order to avoid the use of weight-increasing cast iron liners or costly coating solutions for the cylinder surface, some high performance engines are produced completely from hypereutectic alloys (AlSi17Cu4) which directly provide a wear-resistant cylinder lining.
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