Lubrication

The application of a lubricant (oil or grease) between moving surfaces to reduce friction, minimize wear, dissipate heat, prevent corrosion, and seal against contaminants — the single most important and cost-effective maintenance activity for rotating machinery. Lubricant types: (1) Oil (liquid) — mineral (Group I-III), synthetic (PAO Group IV, ester Group V), and semi-synthetic blends; classified by viscosity (ISO VG 10-1500) per ISO 3448. (2) Grease (semi-solid) — base oil + thickener (lithium, polyurea, calcium complex) + additives; classified by consistency (NLGI 000-6, with NLGI 2 being the most common). Selection based on: speed (high speed → low viscosity, oil preferred), load (high load → high viscosity, EP additives), temperature (high temp → synthetic base, high-temp thickener), and environment (wet → calcium or polyurea thickener, food → FDA H1). Lubrication program elements: correct lubricant selection, correct quantity (over-greasing is as damaging as under-greasing — bearing overheating), correct frequency (time-based or condition-based), contamination control (clean storage, filtered dispensing), and oil analysis monitoring. Studies show that 40-50% of bearing failures are caused by lubrication issues. Per ISO 12924 (industrial gear oils), ISO 6743 (lubricant classification), and SKF bearing relubrication guidelines.