OurTechnology: #3Development Story#02
Totally new dry lubricant coating without using binder
Okitsumo MCF Coating
Dry lubrication using paint film instead of liquid lubrication, such as oil and grease, is becoming the focus of attention. Okitsumo developed the MCF Coating to enhance the performance of dry lubrication. We will introduce the story of the development of this product.
Paints Division Technical Department Global Development Section
Promising dry lubrication
Lubricating oil or grease is typically used for lubrication of machine parts. Dry lubrication with paint uses no oil or grease. This dry lubricating film or dry lubricant coating is called "dry lubrication" because of the dry film as opposed to wet oil or grease.
Because oil and grease are wet, they are sticky and attract dust, vaporize at high temperatures, harden at low temperatures, and cannot be used in vacuum. In contrast, dry lubrication as a solid film is beneficial because it can be used for such applications.
For parts with substantial loads, dry lubrication offers the advantages of excellent abrasion resistance, requires no maintenance to replenish, and has been widely used in the automobile industry. Users are expecting further improvement in lubricity and abrasion resistance.
Limit of dry lubrication - Remove obstructions
The structure of dry lubrication is high lubricity materials from solid lubricants such as fluorine and molybdenum, bound to the base material with resin as the binder. The surface of dry lubrication comprises a mixture of two materials, a high lubricity, solid lubricant and a binder with less lubricity.
That is to say, the binder is an obstacle to improving the lubrication performance of dry lubrication. However, removal of the binder will eliminate the binding force, which causes the solid lubricant to peel. It was well known that fluorine resin offers a variety of excellent characteristics for lubrication performance. If maximum advantage can be taken of this performance, it is easy to imagine that a revolutionary dry lubricant film can be developed. However, it has been thought that it was difficult to bind the fluorine to the base material without binder.
Challenge to difficulties - Battle at the nanosize level
Okitsumo's development team inherited the DNA to accept the challenge to overcome difficulties and to do something different from others. We started development of dry lubricant film with 100% fluorine film without using binder, which was thought to be reckless.
To bind the fluorine resin to the base material without using binder, we first controlled the particles of fluorine resin powder.
Mechanical energy is used to bind it, and the size or shape of the basic fluorine resin powder must be uniform. The particles of fluorine powder are typically 200 nm to 8000 nm; it was found that they did not work well when larger or smaller particles were mixed. A stable dispersion state where the particles do not adhere to each other but stay away from each other is also important. We had a hard time ensuring stable, uniform particles.
The next step was to deposit the fluorine powder to a depth of 5 to 10 μm. (1000 nm = 1 μm, 1000 μm = 1 mm) After a number of trials and errors, we found the conditional balance for firm binding to the base material; finally, it took about two years to complete the MCF Coating. (1000 nm = 1 μm, 1000 μm = 1 mm) Thus, test results certified that the completed MCF Coating had abrasion resistance three times greater than conventional dry lubrication.
With the goal of friction-free
Energy issues confronting humankind are global.
We want to move large, heavy machines with minimal energy. We want to increase fuel efficiency in cars. We are asked to use energy without wasting it, and more energy is used in resistance: friction. If friction is low, less energy can move a large machine and decrease the mechanical strength, which enables a reduction in the size and weight of the parts.
We are advancing and further developing MCF Coating to use its lubrication performance and abrasion resistance to reduce friction in the various types of industrial parts.