Info

General
Componentry manufactured by SelfLube is used principally to guide or control some form of linear motion, often under considerable load.  The range of possible applications is very broad: dies, molds, fixtures, special machines and heavy equipment of all types.  We have even supplied componentry for amusement park rides.  
Our components have an extremely long life -- often exceeding that of the tool or machine in which they are installed. Virtually all of our sales are for new construction.

Self-lubricating Components
Many of our components are self-lubricating.  Self-lubricating components are initially more expensive than conventional components but have the advantage of having permanent lubrication built in. No additional lubrication will be required -- ever. In terms of total life cycle cost (i.e., when the cost of performing periodic greasing is considered) self-lubricating components are always less expensive than conventional components – often considerably so since with conventional components there is always the risk of the lubrication not being performed leading to premature wear out or failure.

Graphite
Graphite plugs provide the self-lubrication.  Graphite has some unusual properties, which make it an excellent lubricant. Chemically, it is one of three common "allotropic" forms of elemental carbon (amorphous carbon and diamond being the other two). But, in contrast to diamond, which has a very dense and very strong three-dimensional crystal structure, graphite has two-dimensional crystal structure -- strong in two dimensions but weak in the third. Its atoms are arrayed in parallel sheets that are easily sheered off, giving graphite its characteristic slippery feeling. Rub a pencil lead and it feels oily. It's not. What you feel is a peeling off of crystal sheets.

In the self-lubrication process, it is precisely these sheered off crystal sheets that provide the lubrication, somewhat like a piece of tissue paper between two pieces of glass.  Initially there is no lubrication but as the two mating surfaces (i.e., bushing and shaft) move in relation to each other, a minute amount of graphite becomes distributed over the wear surface and acts as a solid lubricant. It will stay there a long time, graphite being very stable.  There are some temperature limits.  Although graphite sublimes at 10,000 F in a reducing atmosphere, it will oxidize in air at about 500 F so the temperature should be kept well below this.  Also graphite is one of the few known substances that has a near zero coefficient of thermal expansion.  When a graphite plug is embedded into a metal part, the metal part will expand with heat; the graphite plug won’t. The plug ends up loosening which restricts the temperature range to about 200 F if the plugs have any open surfaces (i.e., not constrained by a mating part).

Additional Lubrication for Graphited Components
In general we don’t recommend it.  The only exception is that when new parts are fitted together, it takes a number of cycles to distribute the graphite over the wear surface so at the onset the parts are running dry.  Some customers find that it is useful do wipe a little light oil (never grease) on the wear surface which would then act as a temporary lubricant until the self-lubricating action gets started.   Beyond that any additional lubrication is actually harmful.  The reason is that liquid lubricants tend to attract dirt and grit, which tends to cause premature wear of the graphite.  Grease is a particular problem.  Graphited components should never be greased.

Aluminum Bronze
Many of our components are made of Aluminum Bronze, which is one of the best bearing materials available. It has a combination of characteristics that is pretty tough to beat: toughness, high tensile strength and a low coefficient of friction when mated with a moving element made of hardened steel.

It also exhibits a property called formability. In the case of a slight misalignment, in a bushing, for example, the Aluminum Bronze has the tendency to slightly re-form or re-distribute itself along the axis of movement thus correcting (or partially correcting) the misalignment. Friction, galling and seizing are all significantly reduced.   A steel bushing, in contrast, does not have this property. Any misalignment here is permanent.  So an ostensibly harder and stronger steel bushing ends up not wearing nearly as well as one made of Aluminum Bronze.  And, when it comes time to replace a worn out bushing, the steel bushing is far more likely to have damaged the pin so two components would need to be replaced.  All and all Aluminum Bronze is a far better choice than steel.  And, when it is graphite impregnated, Aluminum Bronze becomes a near perfect bearing material.

Originally developed by the AMPCO Company and often called AMPCO bronze, Aluminum Bronze refers to a family of copper alloys (principally ASTM C954 and C959) that have a chemical composition of about 85% copper 10% aluminum and 4% iron. Mechanical characteristics are:
Tensile strength (typical):           105,000 psi
Yield strength (typical):              42,000 psi
Hardness:                                 187 - 277 BHN (depending upon alloy)

Load Ratings for Aluminum Bronze Bushings
Individual applications differ but standard handbook PV values for Aluminum Bronze bushings (either graphited or conventional) are as follows:
            PVmax = 40,000 psi x fpm
            Pmax = 4,500 psi
            Vmax = 100 fpm

Testing
SelfLube engaged Detroit Testing Laboratory to perform independent testing of its products in a tough metal stamping application. Their report concluded that using precision laboratory measuring equipment, no wear could be detected after 500,000 cycles of operation.

Special Environments

Clean Environments - for applications, which require clean operation, SelfLube's self-lubricating componentry represents an excellent choice. They completely eliminate liquid lubricants in the form of grease or oil thus significantly reducing the chance of product contamination. In addition, there is no need for an operator or maintenance person to perform periodic lubrication activities, which eliminates another potential source of contamination.

Dirty Environments - interestingly SelfLube's self-lubricating componentry also works well in very dirty environments. With no liquid lubricants, there is far less opportunity to attract contaminants to bearing surfaces. In addition, there is no need for an operator or maintenance person to perform lubrication activities in dirty or potentially hazardous areas.

Benefits

Long Life - SelfLube componentry has an extremely long life, generally longer than the equipment or tooling in which it is installed.

Design Simplicity by eliminating the need to provide for a separate lube system, fewer components are required making designs simpler and less costly

Maintainability - by eliminating the need to perform periodic lubrication (as well as the considerable risk of not performing it at all), end user operating and maintenance cost is lowered.

Clean - by eliminating the need for liquid lubricants, SelfLube componentry significantly reduces the risk of both product contamination and of attracting contaminants to bearing surfaces.

Cost - SelfLube componentry helps reduce non value-added cost for both builders and end users.