Hi Duarte
We are primarily a WDA lab,
Typically WDA will pick wear debris indicating fatigue 3-6 months before VA,
cutting wear can be very difficult to detect with VA until there are fatigue areas to change the VA signal
The down side is of course WDA is expensive if used incorrectly ,
VA is very cost efficient,
this is how we normally advise the monitoring should proceed,
VA monthly every machine you can get to with safety and money restraints,
Oil sample bimonthly (Depending upon contamination levels, perhaps monthly with high contamination levels)
and oil test any machines that show irregular VA signals and all critical equipment.
The oil samples would be screened for significant changes to;
particle count,
viscosity,
TAN
Oxidation
and Water
If VA and or oil test indicate abnormality then resample and complete WDA to visually check what contaminates are present and whether to oil change or not will be apparent.
VA and Oil Testing monthly using WDA or Ferrogram results as the referee is the best system to apply in the Australian environment because the environmental contamination is extremely hard and often under estimated in instances we note like using Basalt mined from an extinct volcano for rail track ballast and wondering why the car drives are melting away are typical results of allowing hard environmental particle ingress into the lubricated area of machinery down under in the big red country.
Regards Rob S