Lubricating Polymer Lead Screw Nuts

By igu-blog-adm (Edited by Kevin Wright and Shizu Yamaguchi)

Customers often ask: “Can I use WD-40 or another lubricant to grease my polymer bearings?” Is external lubrication necessary or advantageous for igus® polymers? We will answer both questions in this blog post. We will also explain why WD-40 or OKS400 can be used, but is not required. The two brands just mentioned will be used as examples in this article, but of course there are other forms and brands of lubrication or lubricants.

Simply put, lubrication is not required for igus® products.

non greased lead screw drives from igus

Let’s take a closer look at the WD-40 lubricant.

If you take a closer look at the composition of WD-40, it quickly becomes clear that it is not necessarily the best lubrication to use without affecting friction. This is due to the fact that WD-40 is called a “penetrating oil.”

This classification means that the lubrication can penetrate cavities, mix with dirt and dust particles and bring them to the surface. It is also not suitable as a long-term option due to its thin consistency.

And why is it that the igus polymer lead screw does not need to be lubricated?

lead screw drive with lead screw and polymer nut

Our lead screw systems are developed for self-lubricating and maintenance-free operation. Basically, you should not do a one-to-one comparison between a lubricated lead screw system and a dry-running system. Due to external lubrication, the coefficient of friction is lower for a lubricated lead screw system compared to a dry-operating system. However, the lubricant also causes high maintenance costs, poorer performance in dirty environments and other additional costs that are often not accounted for.

In some cases, external lubrication of iglide® lead screw nuts can be used to reduce the coefficient of friction or to increase speeds without noise generation. However, you should always consult one of our experts to find out whether this additional greasing really makes sense for your application. The rule of thumb is:

Do not lubricate in abrasive environments because lubricants collect debris, which leads to premature wear.

Another lubrication option is to grease nuts at the beginning of the lead screw system operation. This is an option for better run-in behaviour. After the lubricant has been depleted, wear occurs in almost the same linear pattern as dry operation (as seen in the chart below):

decrease in friction as per German test results with dry operation of lead screw drive

Many manufacturers declare their products to be “maintenance-free.” This usually means that the bearings or lead screw nuts are delivered with initial lubrication. But maintenance is only avoided as long as this lubrication remains intact.

iglide® polymers, in contrast, do not have a lubricating film and no reservoir of grease that is eventually used up. Rather, these polymers are homogeneously embedded with solid lubricant, making igus lead screw nuts truly 100% dry-operating and maintenance-free. Also, the composition of the lead screw nut material ensures that wear is mostly linear without any surprises or maintenance at various intervals.  

Our materials are defined by other unique characteristics. Their engineered composition makes them extremely wear-resistant and resilient. In dirty environments, debris has no grease to adhere to, therefore our polymers have greatly increased service life over conventional, lubricated materials.

In conclusion, dryspin® lead screw nuts  work well with most commercially available lubricants. However, greasing could well lead to increased or reduced wear. If external lubrication is still desired, lithium-saponified, mineral oil-based greases are the best option.

Use in various industries:

The above-mentioned advantages make it possible for dryspin lead screw drives to be used in special industries. In medicine or pharmaceutical technology, for example, it is mandatory that the installed products are absolutely clean, hygienic and very easy to clean. In very dirty environments, on the other hand, it is important that no dirt particles stick to the lead screw nut or in the lead screw because dirt can have a negative influence on the wear and running behaviour. Here you will find all application areas of our dryspin lead screw drives.

Comparison of igus dryspin lead screw nuts to metal solutions

Metal lead screw systems require regular lubrication. Without suitable lubrication, they can start to corrode in a short time and have excessive wear. To prevent this, adequate downtime for maintenance intervals is indispensable. The freedom from lubrication and maintenance by using our polymer lead screw nuts offers a perfect alternative to lead screw systems made of metal.

rusted nut vs greased nut vs polymer nut

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