by Kurt Rommelfaenger, Oil-Rite Corporation
Manufacturing practices are becoming increasingly more scrutinized for their effect on the environment.Real changes are underway in the area of emissions, byproducts, packaging materials, fluid selection, and power consumption – to name only a few.
While environmental payback may be the goal, many of these initiatives encounter obstacles, not the least of which is additional operational costs. Not so with lubrication – the greener the better.
Utilizing very small amounts of lubricant at controlled intervals is productive for a number of reasons:
- Less fluid is consumed resulting in decreased costs.
- Less time is spent cleaning up excess fluid that inevitably finds its way to unintended surfaces.
- There are reduced safety risks, such as product contamination or falling on slick surfaces.
- Optimal lubrication maximizes the life of machinery and minimizes downtime.
Improving lubrication practices can have a greening effect on both the environment and budgets.
Fluid power experts have known for decades the optimal benefit is derived by using a specific amount of oil or grease. Too little lubricant contributes to premature wear. Too much lubricant not only wastes fluid, it may also have a detrimental effect. Excess oil or grease can trap dirt and contribute to heat build-up, causing critical components to bind and wear.
The first step to greening up our lubrication practices is determining why we use more when we could use less.
There are three factors that have contributed to the tendency to over-lubricate:
1) Affordable and readily available lubricants.
2) The tendency to err on the “side of caution”.
3) A preference for simple “hands on” lubricating equipment.
Some manufacturers of lubrication equipment have tried to educate their customers and convert them to precision methods. The green agenda may further assist in calling attention to and re-thinking lubrication practices.
The cost of oil or grease is nominal in comparison to the cost of replacing a chain or ball bearing. With so much at stake, the price of a lubricant has not typically warranted a great deal of scrutiny.
But awareness of the environment is challenging traditional thinking about lubricants. More lubricants than ever are available which use “bio” formulas. Rather than being petroleum based, these lubricants have their foundations in vegetable oils and synthetic esters derived from harvestable resources. These biodegradable fluids have been tested and are being used quite successfully in certain applications.
Green lubricants typically cost more than their petroleum-based counterparts. Therefore, those who oversee budgets and make purchase decisions will be more likely to analyze the expenditure. Fluid price may become a critical factor in switching to more precise methods of dispensing of lubricants.
The Side of Caution
Those who work with machines and moving parts usually understand the importance of lubrication. Without it, most things eventually stop working. Most design engineers and maintenance managers will put lubrication plans into place.
However, when theory meets the practical world, the results are often different than expected. In a corn mill, for example, fine dust collects very quickly and tends to defeat the effects of lubrication. In an industrial food processing freezer, the higher viscosity caused by sub-zero temperatures may prevent the lubricant from reaching its destination.
This is where practical thinking enters in. The person on the plant floor uses the information and resources available to address the problem. That person’s knowledge and/or experience may already warn of the potential pitfalls of inadequate lubrication. Most of us learn about lubrication from experiencing the lack of it. We may know how much is too little, but have never had sufficient feedback to determine how much is too much. Therefore, we err on the side of caution and “make sure we give it enough”. The end result is often over-lubrication. Even if we are fortunate enough to avoid damage to the equipment, we often are inadvertently responsible for waste.
Hands On Equipment
The ultimate responsibility for lubrication often falls with the user – the machinist, the mechanic, the operator. They may be highly skilled and operate very sophisticated equipment. However, they are not likely to have had sufficient instruction on lubrication requirements.
The de facto solution is to utilize very simple lubrication methods that can be adjusted through trial and error. There tends to be a comfort factor with the ability to “tweak” a system to meet the needs of the situation. While every aspect of a complex machine may be precisely controlled, the lubrication is left to a “hands on” approach. Even if the operator knows the exact lubrication level that needs to be achieved, the equipment itself is not likely to deliver an accurate, repeatable amount.
More Precise. . .
Greener lubrication will require more than just improved maintenance practices. In most cases, it will require improved dispensing equipment. More precise lubrication technology is both accessible and affordable.
Most basic lubricating methods rely on gravity for supply and simple valve controls to determine flow rate. While inexpensive, gravity systems have inherent weaknesses:
- The flow rate can be affected by head pressure. There is less pressure being applied to supply lines as the fluid depletes.
- Temperature affects viscosity, which in turn can vary the flow rate.
- Needle valve flow control is unreliable at low dispensing volumes.
- These systems are more likely to be engineered for “hands on” operation than for automated, synchronized control.
A manufacturing facility with simple gravity-fed lubrication systems should consider other methods of lubrication in order to obtain green objectives. There are three types of lubrication systems that achieve more precise dispensing of lubricants:
1) High pressure multi-point
2) Single point electromechanical
3) Positive displacement independent pumps
High pressure systems (over 1,000 psi) are typically powered by a single hydraulic pump. Fluid reaches a valve through a supply line and a precise amount is ejected. Each injection triggers the next in line. The volume of fluid can be adjusted at each valve.
High pressure systems are most cost effective when used with a large number of lubrication points over a long period of time. They require metal supply lines and high pressure fittings. Initial set-up may be somewhat involved, but the systems usually provide years of trouble-free service.
Single Point Electromechanical
Single point electromechanical lubrication units are simple to install and maintain. They are used to dispense grease over a period of two weeks to a year. Relatively low pressure (under 300 psi) output is controlled by a microprocessor. Grease is dispensed evenly throughout the programmed interval.
These lubricators are self-contained units that attach directly to a motor or other housing. They are ideal for unattended locations or where a bare-bones maintenance program is in place. Refillable grease packets and replaceable batteries extend the life of the units.
These units are only available for grease. They are designed to administer a fixed amount of grease over a predetermined interval. If the programmer’s calculations are inaccurate, there is the possibility to over-lubricate. Some units are designed with a safety shut-off when encountering unexpected back pressure (suggesting adequate grease already exists in the housing).
Positive Displacement Pumps
A positive displacement pump utilizes low air pressure, but is able to dispense at a much higher pressure. Flexible supply lines and simple connectors can be used to supply compressed air and oil to the pump. A pump is required for each lubrication point. Both air and fluid supply lines can be daisy-chained from one pump to the other.
Oil-Rite Corporation patented the PurgeX® pump over two decades ago as a break-through product in precision lubrication. The action of the piston inside the pump pushes the precise amount of fluid out and also pulls the next measure of fluid into the chamber. The cycling of the piston is controlled by a timer or PLC, which may already be integrated into the machinery being lubricated. PurgeX® is capable of dispensing a precise, repeatable amount of oil or grease over the course of years without additional intervention.
The same principle of positive displacement can be used with small motorized pumps. These units operate without the aid of compressed air and even in mobile applications that use direct current.
The loss of lubricant is an unintended but often unavoidable consequence of operating machinery. Fortunately, precision lubrication methods are affordable for nearly every application from a single point to a hundred. Optimized lubrication practices will help keep contaminants out of soil and groundwater, and may ultimately yield cost-saving benefits.
For more information, please contact the author:
Designer and Manufacturer of PurgeX®, Positive Displacement Lubrication Pump
4325 Clipper Drive
P.O. Box 1207
Manitowoc, WI 54221-1207
Telephone: 920-682-6173 Fax: 920-682-7699