When Plastic Is Better Than Metals?

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When it comes to real life applications, metals take an important place as some of the most useful materials which we can find on the Earth. Metals are generally hard, sturdy and tough to break yet highly malleable and ductile, which makes it easy to draw them into thin wires or any desired shape with ease. Having excellent heat and electrical conductivity makes them suitable for use in conductors for thermal and electrical energy transfer.

What's more, metals can also be easily combined with either other metals or other elements to form alloys. Alloys can have different properties, and are generally even sturdier than pure metals. Steel, brass, bronze, nichrome and gunmetal are some common alloys. Due to their hardness, alloys are widely used in the construction field, from making perforated sheet metal at  Phoenix Metal Form to railways tracks, in satellites and even our teeth fillings.

Now you might start to wonder why metals and their derivative alloys have not completely replaced plastic. On the surface, it seems that metals are just that much better than plastics that they make them look obsolete. Nevertheless, the properties of metals are sometimes problematic in certain situations:

  • Weight – Metals are generally quite heavier than most elements out there. While it helps to make them harder and less brittle, this can be a hindrance when trying to reduce weight. In instances where weight reduction is a primary concern it might be a better idea to consider using plastics. Other composite materials like carbon fibre can also be considered if costs are not an issue.
  • Ease of fabrications – While metals are quite malleable and are can be melted at higher temperatures to cast them into whatever shapes may be needed, plastics are even easier to handle since they have way lower melting and boiling point. Furthermore, adding colour to plastics is easier (as metals will need to be painted afterwards to get the required colour). Fabrication time is considerably lower as well, which makes mass production easier.
  • Insulation – Metals being good heat and electrical conductors also means that they are completely unsuitable for any application requiring insulation. On the contrary, plastics are perfect for such a job due to their very low conductivity. This is one reason why steel scaffolding used in the mining industry are a good alternative to metallic ones, or why a plastic covering is used on most electrical outlets and plug points.
  • Chemical Resistance – Metals generally react with a lot of chemical reagents, some of them present even in the atmospheric air. Rusting and oxidations are two common chemical reactions which can severely alter the characteristics of metallic objects, often accelerating their wear rate and rendering them unsuitable for most applications. Plastics are not totally immune to chemical reactions, but they do offer a better resistance. Some of the more exotic and complex plastics have quite a long lifespan.