5 Tips for Fastening Using Prevailing Torque Locknuts

All-metal prevailing torque locknuts are widely popular in the automotive, aerospace, construction, and heavy equipment industries. These locknuts require torque to both loosen and tighten them. All-metal locknuts made of stainless steel metal are resistant to high temperature and vibration. They can even withstand chemical exposure. Since we have been in the industry for so long, we often get questions about fastening using torque locknuts. Here we present five tips for using prevailing torque locknuts.

all metal prevailing torque locknuts

1. Avoid overtightening locknuts
Prevailing torque locknuts present resistance to rotation both during assembly and disassembly, which is called prevailing torque. For instance, a Grade C 1/4-20 locknut with 2,850 LB camp load requires minimum of 85 torque. The maximum torque it can withstand is 125. Depending on the grade and size of the locknuts you will use, torque tension requirements vary. So read your manufacturer’s instructions before using them for fastening equipment or machines.

2. Use stainless steel locknuts for high temp applications
Locknuts made of stainless steel alloys resist corrosion and maintain their strength at high temperatures of around 2000 degrees Fahrenheit. Buy locknuts made of 302, 304, 316 stainless steel. They can resist high heat and corrosion more effectively than lock nuts made of other alloys. 316 stainless steel locknuts are also the best option for salt water environments.

3. Use lubricant to prevent galling
Galling is an abrasive wear that occurs between two sliding surfaces. It happens when locknuts are wrenched on bolts. Galling can cause damage to the threads of the locknuts. Your locknuts will fail to function effectively and may not remain tightened during vibration. The best way to prevent galling is to use lubricants. Lubrication creates an extra layer over your locknut and improves corrosion resistance. It makes your assembly to last longer.

4. Look for cadmium coated locknuts for fastening
Cadmium coating provides a more consistent torque tension to locknuts. Prevailing torque locknuts are dipped in cadmium solution and spun immediatly to prevent uneven coating. They are then cured in oven. Use of stainless steel locknuts without any plating could lead to breakages. Cadmium coating offers anti-galling characteristics to the locknuts and they can perform effectively.

5. Follow the manufacturer’s installation instructions
Install the locknuts on a threaded surface using the right size screwdriver. Based on the minimum and maximum torque that needs to be applied during installation, do make sure to tighten the locknut slowly. Slow speed decreases the chances of galling and ensures proper engagment between the mating parts.

Choosing the right locknut for different applications is not a small task. But more difficult is to ensure optimum performance of your assembly after installing the locknuts. Follow the above-listed tips for fastening using prevailing torque locknuts and get the best results. It is always recommended to discuss your needs with a manufacturer before buying locknuts in bulk quantity. Also, follow the instructions provided by your locknut supplier to prevent assembly failure.