Thermal spray low friction coatings can offer excellent means for lower friction. Particularly in high wear applications, higher temperature too, they can play an excellent role in lower friction.

Keep in mind that friction is a function of surface finish. Many of these thermal spray coatings, which include hard facing metals, ceramic, carbides of all type, may very well require grinding, lapping, honing or polishing. Typical ‘raw’ coating finishes can average 300 micro inch or more, the equivalent of sandpaper. But based on their high shear strength, post-finishing values as low as 10 micro inch (Ra) are attainable.

Thermal spray low friction coatings (which include plasma spray) can involve a multitude of compounds, usually in wire or powder form, for enhanced dry film lubrication.

Disadvantages of thermal spraying may be their higher builds or inability to coat uniformly over complex surfaces. For most of these coatings, though the benefits are great, additional machining is required. Another disadvantage is that these coatings are ‘line of sight’, which means coverage is mostly limited to external surfaces or highly accessible internal areas only.

HVOF coating builds typically start at 0.003 to 0.005 inch. Precision parts should typically allow for extra stock (post machining), typically 0.010 inch or more.

Advantages of thermal spray low friction coatings are their ability to resist or reduce wear in most applications. Higher builds allow much longer, sustainable performance or predictable wear rates. Not to mention their higher heat stability, resistance to thermal oxidation. This is especially evident from the ceramic coatings.

Today, thermal spray low friction coatings include a host of compounds, including organic-based materials, like polyesters. Their advantage can be break-in, where low friction requirements are helpful, mitigating wear under highest contact stress is a reality. Be sure your coating provider truly understands your requirements.

Look at thermal spray low friction coatings as combinatory ‘recipes’ for dry lubrication, prevention of corrosion and wear. Here, this technology, materials are often integrated by percent weight, not separable components by layer. The benefit is constant performance, equivalent surface characteristics often ‘top to bottom’.

Some shy away from these products for their ability to fracture on impact. Keep in mind many of these products can be ‘buffered’ for improved flexural strength.