Metal is the most common material used to create fastening solutions, however plastic fasteners offer a different and often more appropriate set of characteristics. Notably, they’re used in space – for example the Hubble Telescope and International Space Station are held together using plastic fasteners.
On a more terrestrial level, plastic fasteners can offer significant advantages over their metallic counterparts for earth-based projects.
Materially speaking we are aware that generally metal fasteners corrode and develop rust over time, especially when exposed to moisture or salty conditions. Corrosion, of course, leads to degradation, so if it’s corrosion-resistant fasteners you need, then often you want plastic. If your product will face salt-water conditions, consider fasteners made from PVC, Isoplast or PET which also give you high strength to weight ratio, don’t absorb water, and withstand chemicals and corrosive substances such as diesel fuel and petrol.
Plastic is resistant to UV rays. That being said, some plastics do absorb UV rays and develop free radicals that corrode, so if UV protection is important, opt for fasteners made from polyimides or FEP.
Plastic fasteners are ideal for electrical or electronic applications where non-conductivity of heat or electricity may be a critical property.
Plastics can cost less - plastic clips weigh less than metal brackets and for many industries such as automotive manufacturing this means improved performance and efficiency. This is just one reason the automotive industry often favours plastic fasteners; another is that plastic screws and bolts can cost less than metal fasteners. Plastic is simply a lower-cost material and when you’re mass producing assemblies and this can amount to substantial savings over time.
Plastic is extremely versatile with the ability to mould into complex shapes in any colour you want. Metal, usually requires secondary processes – for instance, cutting or stamping, drilling and cleaning processes where oil has to be removed to allow the product to be coated.
A good rule of thumb when deciding between plastic and metal fasteners is to think about your application. If environmental, thermal, weight, chemical or electrical properties need to be considered there are probably good reasons to go with plastic fasteners.