Engine Parts: Cast Or Forged? Selection Guide

In the production of engine core components, casting and forging are two mainstream processes, which differ significantly in strength, accuracy, cost, and applicable scenarios, directly affecting the performance of the parts and the reliability of the entire machine. Reasonably selecting casting or forging processes for different stress conditions is the key to engine design and component selection.

1、 Casting process: suitable for complex shapes and low load parts

Casting is the process of pouring molten metal into a mold for cooling and forming. Its advantage lies in the ability to manufacture parts with complex shapes and multiple internal cavity structures, as well as low cost and high mass production efficiency. Cast parts have coarse grains, relatively low strength and toughness, average high temperature resistance and impact resistance, and are suitable for components with low static load and stress.

Typical applications include cylinder heads, intake manifolds, oil pump housings, engine mounts, etc. These types of parts have complex structures and do not require extreme strength. Casting can meet usage requirements and control costs. However, castings are prone to defects such as porosity, sand holes, and looseness, and are prone to cracking under high-strength and high impact conditions.

2、 Forging process: suitable for high-strength and high load critical components

Forging is the process of forging metal billets into shape through high pressure. The metal fiber structure is continuous and dense, and its strength, toughness, and fatigue resistance are far superior to castings. It has high impact resistance, high temperature resistance, and reliability. Forged parts have high precision and few defects, but the process is complex and the cost is high, making it difficult to manufacture overly complex internal cavity structures.

Mainly used for the core load-bearing components of engines, such as crankshafts, connecting rods, camshafts, valves, piston pins, etc. These parts are subjected to alternating loads and impacts for a long time and must be forged to ensure safety. Under the same material, the strength of forged parts can be increased by more than 30%, making it the preferred choice for high-performance and heavy-duty engines.

3、 Selection Principles and Practical Guidelines

1. The core selection criteria are based on the magnitude of force on the parts and the complexity of the structure:

2. For complex shell and bracket parts, casting is preferred, taking into account both formability and cost;

3. Key components that undergo rotation, reciprocating motion, and impact must be forged;

4.When pursuing durability, modification, or high load use, forging parts are preferred;

5. In ordinary household and light load scenarios, qualified castings are sufficient for use.