Differences in functions and properties between "plastic" and "metal"
- specific gravity
- Electrical conductivity
- Shock resistance
- chemical resistance
- High degree of freedom of shape
- Ease of coloring
- Dimensional stability
If the general plastic is set to “1”, the weight of aluminum is 2-3 times, and the weight of iron and copper is 8-9 times.
The properties of plastic materials, which are lighter than metals, are useful in reducing the weight of automobiles and improving fuel efficiency.
Iron conducts electricity, but plastic is essentially non-conductive, making it suitable for the manufacture of insulating components.
On the other hand, plastic is easy to be charged, so it has the feature of being easily dusty.
Some plastics are called "conductive plastics" that conduct electricity.
General-purpose resin has lower heat resistance than metal.
For this reason, it is not suitable for use as a part used in high-temperature environments such as around automobile engines.
In general, metal is more impact resistant than plastic.
However, some plastics have increased strength by adding “glass fiber”.
High impact-resistant plastic has been used as a material for automobile bumpers.
Metals are vulnerable to oxidation and rust, except for some types.
On the other hand, plastics are characterized by their weakness to organic solvents, but there are types with high chemical resistance.
In the case of metal parts, even if the parts require rust prevention, rust prevention is not necessary because plastic does not rust.
High degree of freedom of shape
Because general-purpose resins have a low melting point, they are easier to mold than metals.
In addition, it has characteristics suitable for mass production, which can reduce the cost for product production.
However, the shape and productivity suitable for each molding method vary, so it is important to select a molding method that suits the part to be manufactured.
Ease of coloring
Resin and metal can be plated or painted, but in the case of plastic, it can be molded in a colored state by mixing dyes into the material.
Suitable for mass production of parts of the same color.
Compared to metals, plastics are less susceptible to temperature changes, so characteristics such as rigidity change as the temperature rises.
General-purpose resins are often available at lower prices than metals.
On the other hand, high-performance plastics such as engineering plastics are often more expensive than metals.