July 8, 2020

6-Step Guide to an Improved Greasing Procedure

An improper greasing procedure can include anything from inadequate or too much grease, incorrect grease, poor grease gun calibration or even greasing oil wetted components.

Manual grease guns have problems with volume and pressure control and regular calibration of your guns is strongly recommended. Grease guns can produce between 1 gram and 1.5 grams per shot which can result in significant over lubrication per point unless the output is known. Grease guns are also capable of producing 15,000 – 20,000psi per stroke. Pressures like this are capable of blowing out bearing, and a careless approach can result in over lubrication resulting in a bearings life-cycle being significantly reduced. Over greasing of bearings is far more common than under greasing.

Therefore, it’s important to follow a well defined greasing procedure: the correct lubrication, in the correct amounts, at the correct times.

6-Steps and Best Practices

  1. Grease Type

    In this step, you need to determine the type of grease needed for your application (e,g, electric motor bearings use a different type of grease than pump bearings). Some greases are compatible with each other while others are not and this incompatibility can cause catastrophic failures. Most grades of grease will be an NLGI 1 or 2. Human error can happen and applying the wrong lubricant can happen, so color coding grease guns and grease fittings can drastically help to alleviate this issue. Additionally, consider having a grease gun color that matches corresponding grease fitting caps.

  2. Amount of Grease

    This information can easily be determined through a simple calculation. All that is needed is the bearing width and outside diameter. If the information is not available, then determine the bearing type, and manufacturer; often the bearing dimension will be published on the website. Input this information into the following equation:

    G = 0.005 x B x D (grams)
    Where:
    G = weight of grease, grams
    D = bearing outside diameter, mm
    B = bearing width, mm

  3. Greasing Frequency

    This calculation is used to determine how often to provide greasing from the amount calculated in the second step. The greasing frequency calculation is a little more complex and requires additional variables to be considered as follows:

    t = K {(14×106 / n √ d) – 4d}
    Where:
    t = frequency (hours)
    K = sum of all correct factors (see tables below)
    n = Speed (RPM)
    d = bore diameter (mm)

    Greasing Frequency Variables

  4. Grease Gun Calibration

    Now that grease quantity and frequency is determined, the amount the grease gun will expel with a “shot” is needed. Greasing in “shots” is generally provides erroneous results. Rather than grease in “shots” one should rather provide greasing in the terms of quantity as a “calibrated shot of grease”.
     
    There are many ways this can be calculated – through a metering device, ultrasonic greasing, or measuring the mass of a shot. Of these three, the simplest method of calibrating grease guns is by taking a shot of grease and measuring the mass. Pump 10 strokes of grease onto a scale and measure the mass. Divide by 10 to get the average amount of grease being delivered per stroke. Do this calibration at least once a year. The number that is quantified can be used in terms of a “calibrated shot” of grease; this allows the technician to know exactly how much grease is being pumped into the equipment.

  5. Preventing Contamination

    Now that we know the amount of grease required, the frequency, and amount of grease the grease gun will expel, we need to create a simple greasing procedure to ensure contamination does not occur. Use the following tips to maintain your grease guns and fittings:
     
    · Determine the correct grease by the color-coding system in place and the PM work order.
    · Open grease relief valve if applicable.
    · Wipe the gun tip and fitting before application. Remove the fitting cap on the grease fitting.
    · Inspect the grease fitting to ensure it is not leaking or defective. Replace defective or damaged fittings.
    · When delivering the calculated grease amounts, never hold the nozzle onto the grease fitting when pumping grease with the grease lever.
    · Be conscious of the risk of over pressurization and do not force the lever arm if there is strong back pressure.
    · When grease delivery is completed wipe the gun tip after application.
    · Always replace the cap on the fitting to prevent contamination.

  6. Housekeeping

    Once you’ve finished the required greasing of your components, the final step is housekeeping.
     
    · Keep guns clean and avoid laying them on dirty surfaces. Repack on a clean bench using a gun loader fitting.
    · Keep grease guns covered when not in use.
    · When repacking grease guns from a pressure line, wipe down the fitting and the pressure line to prevent contamination.
    · When repacking with tubes, move to an environmentally controlled area, such as a control room, to replace the tube.

Interested in learning more? Contact our team of reliability specialists and find out how we can help you with your lubrication program.

By Drew MacRae, Training & Solutions Manager, Reliability