Ball Mill Rana Gruber
The ball mill at Rana Gruber. Photo: Rana Gruber

Major savings through route-based condition monitoring on ball mill

Using the handheld instrument Leonova Emerald and DuoTech accelerometers, Norwegian mining company Rana Gruber monitors the mechanical condition of the production-critical ball mill in this case study. The planned replacement of a damaged main bearing, detected through route-based measurement, saved the company significant amounts.

Ball mills are a low-speed application (typical rotational speed is 10-20 RPM), where bearing damage can be challenging to detect. Condition monitoring of the ball mill began in December 2016 and right from the start, the readings indicated potential damage on the output main bearing.  

As the months passed, the readings remained at a fairly high but stable level, while the BPFO values showed an increasing trend and clear BPFO matches. When the bearing was replaced during a planned maintenance stop, outer race damage was confirmed. 

Download full case study

Case Study
Filename/description Language Size Modified
CS_021B_Ball_mill_RanaGruber_NO.pdf English (United Kingdom) 910 kB 11/8/2018
This case study describes the detection of bearing damage on one of the main bearings in a 60 ton ball mill.


In this heavy industry, condition-monitoring equipment must withstand mechanical and environmental forces as well as potentially explosive atmospheres. The SPM product range fits the bill.

Leonova Emerald

The handheld data collector Leonova Emerald® is the ultimate frontline tool for maintenance engineers and technicians.

DuoTech accelerometers

DuoTech offers a powerful combination of our patented HD technologies, providing maximum flexibility. The combination enables superior lubrication and bearing monitoring – covering the entire bearing deterioration process – as well as the detection of vibration-related problems.