Plastic Fasteners in the Military

The Military Demands Plastic Fasteners

plastic fasteners are used in many military componentsAs you can imagine, the demands of the military and the environments in which the military works can be hard on machinery and components. The U.S. Navy is especially hard on equipment, bearings, screws, and more because of its work in humid and constantly wet environments. Metal often corrodes, so metal fasteners may not be the best choice for all applications.  Enter plastic fasteners.

Not so fast. Unfortunately, not all plastic fasteners are right for the job, either.

Let’s take a look at two superior options, when it comes to getting the high performance out of a plastic material that’s needed in the military applications: Acetal and DuPont’s Acetal resin, called Delrin.

Acetal and Delrin

Both Acetal and Delrin are thermoplastics. They can be heated into a liquid and then cooled to create a solid that will retain nearly any shape. Acetal and Delrin are ideal for use in a wide variety of applications that require sliding actions. Both materials are often used to create plain bearings, gears, and slide plates, and they are both FDA and 3A compliant. With such high compliance ratings, they make a good choice for a wide variety of military machinery.

Why choose Delrin over Acetal?

Although Acetal and Delrin are very similar, there are some differences that are extremely important to consider, especially in a military setting. Acetal is a semi-crystalline, non-amorphous thermoplastic. Delrin, on the other hand, is a homopolymer.

Homopolymer Acetal has a high crystallinity, which is able to improve the mechanical strength and creep resistance of the material. It is also generally resistant to a wider range of solvents and common chemicals than Acetal, which can come in handy in military applications. It is able to avoid corrosion, like rusting and dezincification, which means it is a great choice for replacing traditional metal components.

There are other considerations that make Delrin a good choice when it comes to the Navy and the military in general. Delrin has a higher melting point than Acetal at 175 degrees Celsius. Acetal’s melting point is, at the very most, 173 degrees Celsius.

Delrin AF integrates 10 to 25 percent PTFE fluorocarbon fibers which are dispersed in the thermoplastic resin, while Acetal does not. This allows the material to retain the strength, toughness, and dimensional stability of Acetal, but with the added properties of PTFE, which is also known as Teflon. With these added fluorocarbon fibers, components made of Delrin can sustain high operating loads at high speeds with very little wear, all thanks to Teflon’s slippery, yet solid, characteristics.

PTFE bearings also require absolutely no lubrication, which cuts back on the costs and time associated with maintaining equipment. This material boasts one of the highest continuous service temperatures among plastic materials.

In addition to Delrin AF, DuPont also offers other thermoplastic materials under the Delrin name that are created with various goals in mind. They include toughened resins, UV resistant grades, and extrusion resins.

Additional attributes of Delrin that are worth considering

Delrin’s chemical composition, regular molecular structure, and high degree of crystallinity set it apart from other materials, but there are a few other attributes that make it an especially good choice for military applications.

  • Can withstand temperatures as low as –40 degrees Celsius
  • High mechanical strength and rigidity
  • Unbeatable fatigue endurance
  • High resistance to repeated impacts over a long period of time
  • Is able to resist moisture, gasolines, solvents, and many other neutral chemicals
  • Superior dimensional stability
  • Natural lubricity
  • High resilience
  • Good electrical insulating characteristics
  • Ease of fabrication

Summary

Although Delrin is a high-quality thermoplastic that can definitely excel in a military setting, other Acetal products may be a better choice depending on your particular application. Before deciding on a product, a full analysis of the upcoming project is needed.

Choosing the right fasteners and components for a sensitive and important project can be a real challenge. If you need a little help deciding which materials would be best, don’t hesitate to contact us. We’re happy to help you ensure your next project is completed without a hitch.