Nylon 6 vs. Nylon 6/6: What’s the Difference?

Nylon 6 and Nylon 6/6 are common materials used in industrial applications such as gears, wear pads, cable sheaves, and sleeve and slide bearings, to name a few. While all materials in the nylon family of polymers share specific characteristics, not all nylons are the same—and there are essential differences between these two materials in particular (beyond the extra “6”). They are manufactured using different modes of production. Nylon 6 is produced by casting, while Nylon 6/6 is an extruded product. The physical characteristics of these plastics gives each its own distinct qualities. Selecting the one best suited for your application will result in a better outcome for your project.

Why Can’t I Use Nylon 6 and Nylon 6/6 Interchangeably? 

Here’s what could happen if you select the wrong nylon for your application: 

• Underperformance at Service Temperatures. All nylon materials have melting points, but the amount of heat that Nylon 6 and Nylon 6/6 can tolerate under the real-world conditions of any specific application is different. Breakage and contamination are both a possibility when using a material that does not have the correct thermal resistance. 
• Premature Wear. It’s important that your material has the appropriate strength and flexibility to avoid failure in your application. Having your parts fail prematurely can jeopardize the safety of your end users, require unplanned downtime for maintenance, and cause avoidable production delays. 
• Unnecessary Costs. The wrong material selection could lead to spending more than you need to on your nylon materials before you even put them into use. This can occur if you’re using one formulation when another would suffice (at different thicknesses and for different shapes, cast materials can actually be less expensive than extruded). Also, understanding the benefits of each nylon and how they apply to your project can save you thousands of dollars on refabrication, repairs, and replacement of parts. 

Key Differences Between Nylon 6 and Nylon 6/6 

First, let’s recognize the similarities between Nylon 6 and Nylon 6/6. Both have high mechanical strength and impact resistance, resistance to UV rays, and a lightweight feel. Now, here are notable differences between the two materials: 

Nylon 6  

Nylon 6 is a cast material that has a slightly lower continuous service temperature rating than Nylon 6/6 but can endure a higher combination of load and speed in bearing applications (commonly displayed by a PV rating). Nylon 6 has all of the core characteristics of any nylon polymer, including stiffness, toughness, excellent mechanical dampening, and great insulation qualities. Cast nylon has the highest rate of absorption of all the PA formulations and therefore may not be the best choice in wet environments. It can be easily enhanced with additives like glass fiber and other compounds and is most often less expensive than Nylon 6/6. 

• Applications. Typical applications include bearings, forming dies, insulators, thrust washers, valve seats, pulleys, rollers, and more. 
• Popular varieties of Nylon 6. Best-selling Nylon 6 brands and special formulations at Cope Plastics include Nylatron MC907, SUSTAMID 6G, Nycast 6PA, Nylatron GSM, Nycast 6PA MoS2, SUSTAMID 6G MoS2, Nylatron NSM, and Nycast GX.

Nylon 6/6

Nylon 6/6 shares many of the same characteristics as other nylon polymers, including Nylon 6. The significant differences between the two come down to how stiff and durable they are. Nylon 6/6 stands apart from Nylon 6 in a few major ways that you should consider when it comes to purchasing material for your project: 

• Greater Service Temperature Range. Continuous service temperature can best be explained as the temperature above which significant and permanent degradation of the plastic occurs with prolonged exposure. Nylon 6/6 has a continuous service temperature of 210°F, slightly higher than Nylon 6 at 200°F.
• Chemical Resistance. Nylon 6/6 is more resistant to acids than Nylon 6, making it better suited for hazardous projects because it can withstand exposure to harsh chemicals. Both cast and extruded nylons should be considered as displaying “Good” chemical resistance, not “Excellent,” and certainly not “Inert,” but for the price point, they perform better than commodity plastics.
• Popular varieties of Nylon 6/6. Best-selling Nylon 6/6 varieties at Cope Plastics include Nylon 101, SUSTAMID 66, Nylatron GS, SUSTAMID MoS2, Nylatron GF30.

Find the Right Nylon for You

The process of choosing the right material for your application is critical to the success of your project. To find the ideal material for your application and gain more peace of mind, head to our website to use our simple and easy online Mechanical Material Selector or contact a Cope material expert directly for advice. Our team is waiting to answer your questions and help you succeed! Call us at 1-800-851-5510 or send an email to corp-web@copeplastics.com to get started. 

Note: All of our evaluations in this article are based on the virgin formulations of Nylon 6 & Nylon 6/6. There are many custom formulations of both products that can be utilized to meet our customers’ specific needs.