To introduce the developing course of guard what kind of?

We know that in every stage of development, the engine under guard by raw material and manufacturing process is different, the first stage is resin, its simple process, low cost, but it's easy to have a plastic ageing, the phenomenon such as not durable. Through horizontal design, easy to reduce, cause the phenomenon such as the palm, less security. The second stage is the manganese steel, it is manufactured by hot rolling material, general models mold, the cost is low, but prone to rust. The third stage is the plastic, its light weight, strong toughness, generally USES planar design, easy to stick to engine caused by engine heat dissipation is not good, reduce vehicle through sex, cause potential safety hazard. And the fourth stage is aluminium alloy, ordinary aluminum manufacturing, applying general mold, light weight, good heat dissipation, but prone to deformation, in order to avoid resonance phenomenon, generally increase the distance of sheeting and engine, prone to the palm. And guard the fifth stage is 3 d, laminating, does not affect heat dissipation, to conduct a comprehensive protection.