The Power of Lubricating with Grease

Greases are invaluable in a host of operations due to their density. Derived from oils, greases typically have thickeners added to them to make them usable in homes and on industrial equipment. While not appropriate for every operation, greases provide a viscous coating in conditions where oils are too thin to maintain effective operation. Keep in mind that all lubricant types, including silicone grease, have specific uses, whether it's as a wheel bearing grease or to keep a bicycle running smoothly.
 

Grease Uses

Greases have a variety of uses, including applications in:
  • agriculture
  • automation equipment
  • engine parts
  • food industry and production
  • manufacturing.

Greases facilitate the interaction between moving parts when applied properly. Depending on the exact type of grease, they may also:

  • cool surfaces
  • prevent oxidation
  • protect surfaces from contamination
  • reduce the development of rust
  • transfer heat.

All of these qualities keep equipment running longer and generally with less maintenance.

Grease Defined
While greases can include a variety of ingredients, the standard components are a fluid mixed with one or more thickeners that result in a non-liquid lubricant. In general, greases are applied with an air-pressured lubricator. Greases do not drip as oil would, and they can often provide greater cushioning between parts, if the situation warrants it.

Bases for Greases

The oils used as the base for grease can range from petroleum or mineral oil to synthetics, such as silicone and polyolefins. The type of oil used determines the best use for the grease itself. In general, the thicker the base of the grease is, the greater its ability is to operate effectively in higher temperatures. The thickness of a liquid is technically referred to as viscosity: While more watery liquids are less viscous, thicker ones are referred to as more viscous.
 
Greases capable of operating at higher temperatures have higher "dropping points." That means they must reach a certain temperature range before reverting to liquid. This explains why choosing the right grease and applying it properly are important. If grease is too watery (or not viscous enough), it will leak off. Alternately, if the grease is too hard, it won't reach the crevices in some machine parts.
 
While organic thickeners are most commonly used for both soap and non-soap based greases, inorganic thickeners can also be useful in certain circumstances. Other additives may enhance performance to make some greases more effective in unique environments.

Types of Grease

Some of the more common types of grease include the following:
  • Extreme pressure (EP) greases incorporate additives to prevent breakdown. They often rely on chemical reactions between the metal components and the grease ingredients.
  • Silicone greases generally are non-reactive or inert, making them useful in environments such as laboratories. While some oil-based greases may react with or breakdown rubber gaskets or other internal gear, these provide reliable lubrication, often at high temperatures where needed.
  • Soap-thickened greases tend to have barium or lithium bases. A lithium complex grease is rated for high performance and includes a soap/salt thickener. Lime-soap, or calcium soap, grease is commonly used to lubricate axles and pumps. General purpose grease in this group may combine two types of greases to work in many different pieces of equipment.

Grease Storage and Handling Tips

All greases require a clean and dry storage environment, whether it's a manufacturing facility or a home garage. Extreme temperatures and fluctuations can cause:
  • chemical breakdown
  • contamination through moisture development
  • reduction in function.
Similarly, properly handling greases based on manufacturers' recommendations is also essential to ensuring they work their best. Even minute dust particles contaminating the grease can create equipment failure.
 
Another important factor to keep in mind when dealing with greases is that all greases will begin to deteriorate over time. With proper care, it's possible to prolong shelf life. The following care tips can be helpful:
  • Keep greases in their original containers.
  • Make sure lids and caps are tightly sealed, as carbon dioxide and oxygen can react with the compounds.
  • Temperature, as mentioned above, should remain within recommended ranges: generally no lower than 32˚F and no higher than 77˚F. However, greases tend to remain efficient in ranges no lower than 0˚F and no more than 110˚F. Sediment or solidification can occur in temperatures that are too cold, while the grease may begin to oxidize or separate in temperatures that are too hot.
  • Water is the enemy of grease, especially synthetics. Grease will absorb moisture, reducing its effectiveness and potentially causing it to damage equipment.

Grease Disposal

Grease disposal is no easy matter. Most cities prohibit discarding used products in the trash. They often designate specific days when residents can drop off hazardous materials at a local site. Some reports reflect that a large percentage of waste products do end up in landfills and water runoff through accidental leakage.
 
For industry, the safety issues compound. In specific circumstances, regulations require the use of biodegradable greases. Landfills must get special permits to burn or otherwise use grease. While attempts at better filtration are increasing, recycling is not a popular option for most companies.

Safety Issues and Grease

As with many materials, you will have to take some extra safety precautions when working with grease and/or a grease gun. Injuries can occur when using an air pressured (or pneumatic) grease gun or when handling the grease itself.
 
To inform users of the potential danger associated with various types of greases, manufacturers classify them into several categories, ranging from those known to possess cancer-causing compounds to those that have been proven harmless.
 
Resources
 
Hughes, Ron (n.d.). Understanding the Basics of Grease. Retrieved January 28, 2008, from the Reliabilityweb Web site:
http://www.reliabilityweb.com/art04/understanding_grease.htm.

Industrial101.com (n.d.) Industrial Lubricants. Retrieved January 28, 2008, from the Industrial 101 Web site: http://www.industrial101.com/equipment/industrial-lubricants.aspx.

Sivik, Matthew and Bill Ward, The Lubrizol Corporation (2006). Understanding Calcium Sulfonate Thickeners. Retrieved January 28, 2008, from the Machinery Lubrication.com Web site: http://www.machinerylubrication.com/article_detail.asp?articleid=909&pagetitle=Understanding+Calcium+
Sulfonate+Thickeners.