Good lubrication practices can help cut a site’s energy consumption and, in the process, possibly turn lubrication personnel into corporate heroes.
By Ken Bannister, MEch Eng (UK) CMRP, MLE
If you want to assure a reasonable life span for mechanical equipment with rotational and/or sliding elements built into its design, you must lubricate it. The benefits of doing so, however, go well beyond the health of the lubricated equipment.
Virtually all machine designs facilitate some form of lubrication by incorporating one or more means of lubricating bearing surfaces. These solutions range from something as simple and austere as grease nipples at major bearing points to full-blown, centralized, automated re-circulating-oil systems. Regardless of the method/system, it’s incumbent on the end user to understand all of the benefits that can be achieved through effective lubrication practices, and the importance of implementing and adhering to a lubrication regime based not on OEM recommendations, but rather on ambient and machine operating conditions.
Arguably, of all the interactions that can be performed between a person and a machine, lubrication will be one of the least expensive and, collectively, will deliver the greatest impact on machine performance in terms of its life cycle, availability, reliability, production throughput, quality, energy use, and carbon footprint.
Stamping-press case study
The stamping press featured in this story is one of five 500-ton pure mechanical, straight-side presses at a site. The press stamps out automotive body pieces—requiring significant energy transfer.
This press employs an OEM-designed centralized box-cam-style automated recirculating-lubrication system that delivers a local re-refined (reclaimed) extreme-pressure (EP) 150 Gib and Way oil to rotating main and countershaft bearings and sliding surfaces. The system had not been calibrated since commissioning.
Energy is supplied by an electric variable-speed drive (VSD), and the press is used 12 shifts each week, for a total annual usage of 4,800 hr. Equipment monitors energy consumption over a 48-hr. period calculated an average use of 25.2 kW p/hr.
The press was observed under load with an infrared camera that showed lubrication delivery was unbalanced on the main and counterbalance shaft bearings. A 45 F temperature range between bearings indicated the need for immediate re-calibration of the lubrication system. The lubrication system also had numerous dirty filters. After the lubricant and filters were changed out, the press was restarted and the cam lubricators re-calibrated.
Back in production and monitored over another 48-hr. period, the stamping press showed a dramatic 18% reduction in energy consumption, i.e., with average usage at 20.5 kW p/hr.
Based on 4,800 running hr./yr. and a delivered energy price of 10 cents/kWhr the energy-reduction savings for one press was calculated as follows:
(25.2 x 4,800 x 0.1) – (20.5 x 4,800 x 0.1) = (12,096 – 9,840) = approx. $2,256 per press (or $11,280 for all five presses)
The energy savings of 112,800 kWhr was also calculated against the carbon footprint. Using the Carbon Trust calculation of 1 kWhr = 0.000537 emission tonne equivalency, this automotive manufacturer accrued a carbon credit of approximately 60 tonnes—for just its presses.
Additional accrued benefits from the lubrication program implementation included:
- reduced purchase costs through lubricant consolidation
- reduced lubricant and replacement bearing carry costs
- reduced lubricant stock rotation requirement
- increased inventory real estate
- reduced lubricant waste that could meet corporate environment and sustainability program mandates (ISO 14000 mandate).
Making engineered choices in lubricants, lubricant application devices/systems, and lubrication control will ensure that equipment delivers as designed, and, as an added bonus, help a site significantly cut its annual energy costs. The bottom line? A good-lubrication-practices program can front energy-waste-elimination efforts and be solely underwritten by the energy savings. MT
Contributing editor Ken Bannister is a Certified Maintenance and Reliability Professional and certified Machinery Lubrication Engineer (Canada). The author of Lubrication for Industry (Industrial Press, South Norwalk, CT) and the Lubrication Section of the 28th Edition of Machinery’s Handbook (Industrial Press), he can be reached at firstname.lastname@example.org.