GMORS low friction solutions

Technical Papers

The friction characteristics of rubber parts can be result of many factors, such as the nature features of elastomers, the addition in rubber compounds, the surface finish of the molds or post-processing techniques to rubber during manufacture. Via some of controllable factors, the way to reduce friction can therefore be various and tailored for each individual application.  To help customers find the best low friction solutions with GMORS, a series of lubrication methods for rubber parts will be introduced in the following article.

Lubrication, like many kinds of coatings or inner-lubricated, is a cost-effective option for most of customers today. It helps avoid unnecessary high cost from over strict surface requirement on tooling. Also, for standard products, it is relatively efficient and widely applicable when compare to more customized solution, like configuration design of seal.  GMORS lubrication is categorized as diagram for your reference in Figure 1 below.

Figure 1. Categories of Lubrication for Rubber parts

GMORS products mainly can be dry, wet or internal lubricated.

Wet lubrication

Wet lubrication is liquid or grease applied on product surface, and proper mineral oils, synthetic oils or silicone oil can be chosen depending on product material and usage applications. Actually, many users dip or apply the parts with lubricants before assembly, and some users order the parts with lubricants applied to avoid extra work procedure. However, wet lubricants will easily pollute any liquids or oils used in production lines. Parts after unsealing must be assembled as soon as possible in case of evaporation and lubrication failure, and the remainder must be resealed carefully and stored away from direct sunlight and high temperature.

Dry lubrication

Dry lubrication can be divided in two types, and the first one is powder coating, e.g. talc, graphite, MoS2, etc. The advantages are easy work procedure and low cost like wet lubrication, but it also carries pollution (Talc is white powder; graphite and MoS2 are both black powder while MoS2 shines some metallic gloss. As again this is not applicable in production lines that require no pollution, the second type “Film-forming polymer lubrication” is therefore highly recommended.

The main advantage of “Film-forming polymer lubrication” is that it will not generate any powder as it covers the part surface with a polymer film in thickness from nanometer to millimeter. Common material with low friction is PTFE coating (normally in color transparent, red, orange, green, blue, gray and white). It benefits the assembly line a lot, like preventing mix-up with color added, preventing sticking and low friction for higher production efficiency. To best satisfy customers, a study has been made on advanced PTFE coating in another article.

Another type is Silicone-based transparent thin film that relatively shows better elasticity with low friction than the above. It is suggested to be used for assembly, not for dynamic service application. Though the above two coating materials will not generate pollution, but it is still not recommended for high cleanliness requirement industry.

One more type in the “film-forming“ category is the Parylene. It is a vapor deposition coating providing more uniform surface and thickness. Parylene coating not only can lower the friction of rubber seal, but also make rubber seal less reactive towards moisture or chemical attack. However, the cost of parylene is relatively high.

Internal lubrication
All the above are external lubrication for assembly usage. GMORS internal lubrication is suggested for customers that require dynamic usage, where the low speed abrasion or vibration may happen. With proper lubricants, e.g. wax, PTFE (for high pressure), graphite or MoS2, added to rubber compounds, they will permeate to the part surface during usage and bring long-term lubrication effect, making the product life longer.

Among all these options, the best solutions will always depend on what you need. Some may need simple powder coating for easy handling, some may need internal lubrication for dynamic usage, and others may need strict cleanliness control or several coloring to identify similar parts. In addition, any applications with high standard or specific requirement are highly recommended to consult us for further details in your working conditions.

GMORS Solution
To offer customers the total satisfaction service, and at the same time, the uppermost balance on quality, low defect rate and cost for each kind of applications and usage requirements, GMORS suggests:
1.) Oil or powdering coating for parts with lubrication requirements but no pollution concern.
2.) For parts with pollution concern, dry lubrication can be used, e.g. PTFE or 0P0012 (Silicone-based thin film). If your application is specially for high cleanliness demand industry, please contact GMORS for further information.
3.) For parts under dynamic usage, internal lubrication is the main recommendation.
4.) Least stick-slip phenomenon will be found in parylene but the cost will be the highest.

Some other post processing method to the surface can be of your choice. Please contact GMORS if the surface treatment you need is not listed here.

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