Oh, Nylon…the material of choice for so many. Invented in the early 1930’s by chemical giant DuPont, this trusty polymer is still an outstanding material for a wide variety of applications. Nylon is so well known that it tends to be the default choice for many first-time customers who are new to the vast world of plastics. Although nylon may seem like a safe multipurpose material pick, one must always carefully consider the requirements of a project when choosing a material for plastic fasteners.
Even the popular nylon has weaknesses, such as an inability to withstand extreme high temperatures and long-term contact with water and many organic solvents. Nylon fasteners also do not perform well where there is the need for low out-gassing, ultra-high strength, or clean and easy machining. Nylon also does not cut crisply without the need for extensive cleaning. Other materials, such as Delrin, are better suited to cutting. As a condensation polymer, nylon fasteners cannot be left in water as they are highly absorbent.
With all these drawbacks, where did Nylon’s reputation as a top all-around plastic material come from? Well, for one thing, it’s cheap! Consider PEEK, a plastic that is much more chemical and heat resistant than nylon. PEEK fasteners can tolerate temperatures almost as high as 500° Farenheit while Nylon fasteners can only handle around 300° for short periods of time. PEEK costs around $60 per pound while nylon only costs around $2.30. Polyphenylsulfide (PPS) can also withstand high temperatures and only costs $10 per pound but is extremely brittle, even when reinforced. For projects that have no need of high levels of temperature and chemical resistance, nylon fasteners are the economical choice.
Nylon also has certain useful chemical properties. Nylon fasteners are relatively easy to glue and can be colored almost any hue simply by using fabric dyes dispersed in hot water. It can be permanently immersed in gasoline or motor oil without fear of corrosion, as it is excellent in and around many petroleum-based materials. It is also fairly strong and can be made even stronger with the addition of reinforcement fibers such as carbon, glass and metal. These fibers add strength and dimensional stability. There are also many special-use nylons which use a wide variety of processes and additives to alter and improve nylon’s natural properties. For example, nylon fasteners can be made fire-resistant to the extent that they get a UL rating of 94-V0. Nylon can also be modified to extend its sustained use temperature range and can be made stronger with many different types of reinforcement fibers including carbon, glass and metal.
Nylon is also very easy to mold and becomes water-like when heated in a plastics extruder or injection molding machine. This melting property has the benefit of allowing nylon to be pushed into very small spaces. The minimum annular distance between two plates for Delrin is forty thousandths while the minimum distance for nylon is only fifteen thousandths.
All of these properties make nylon an alluring and cost-effective choice for the novice engineer. Even when a few of the comparative factors are examined, it can be seen that there are still unique properties which make nylon fasteners competitive with respect to fasteners made out of other plastics. Yet it is important to always pick your material to fit your project. No single plastic can fit all applications.
Looking for more information on the many grades of nylon? Download our complimentary guide!