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Frequently Asked Questions

Clear answers to the questions we are asked most about condition monitoring, vibration analysis, on-site balancing and shaft alignment.

What is predictive maintenance?
Predictive maintenance is a strategy that measures the actual condition of equipment to anticipate failure before it happens and plans maintenance around that prediction. It differs from calendar-based preventive maintenance in that the timing of intervention is set by measured data rather than a fixed interval. Vibration analysis, shock pulse measurement, thermography, oil analysis and ultrasound are the most common techniques. A well-built programme markedly reduces unplanned downtime and lets spare parts and labour be planned in advance.
What is the difference between condition monitoring and predictive maintenance?
Condition monitoring is the activity of measuring and tracking equipment health: data is collected, evaluated and trended. Predictive maintenance is the management strategy that turns that data into a maintenance decision. In other words, condition monitoring is the method and predictive maintenance is the purpose it serves. A plant that performs condition monitoring but never connects the data to its maintenance plan is not practising predictive maintenance.
Which faults can vibration analysis detect?
Vibration analysis detects the following faults on rotating equipment: bearing damage (inner race, outer race, ball, cage), gearbox faults (tooth breakage, wear, eccentricity), unbalance, mechanical looseness, parallel and angular misalignment, resonance, belt and pulley problems, electric motor faults (broken rotor bars, air gap eccentricity), and cavitation in pumps and fans. Each fault type has its own frequency signature in the spectrum, and diagnosis rests on recognising that signature.
What is SPM HD and how does it differ from conventional vibration measurement?
SPM HD is SPM Instrument's patented shock pulse measurement method. It measures the high-frequency shock waves produced by metal-to-metal contact on bearing surfaces, amplifying them through order-synchronous sampling and digital signal processing. Conventional vibration measurement sees the motion of the machine as a whole and becomes weak at low speed; SPM HD can detect bearing damage even at speeds as low as 0.1 rpm. The result is expressed as two decibel values: HDm (damage severity) and HDc (lubrication condition).
What are the ISO 10816 and ISO 20816 vibration limits?
ISO 10816 (and ISO 20816, which supersedes it) assesses machine vibration severity through broadband RMS velocity (mm/s), grouping machines into classes by power and mounting type. For rigidly mounted machines between 15 and 300 kW, for example, Zone A (newly commissioned) is 0–2.8 mm/s, Zone B (acceptable for unrestricted long-term operation) 2.8–4.5 mm/s, Zone C (restricted operation) 4.5–7.1 mm/s and Zone D (risk of damage) above 7.1 mm/s. Limits vary by machine class, so the relevant part of the standard and the manufacturer's instructions govern.
What is on-site balancing and when is it used?
On-site balancing is the balancing of a rotating part without removing it, in its own bearings and at operating speed. It is applied to fans, propellers, impellers, crusher rotors and rolls. Unlike workshop balancing, the rotor is balanced with its own bearings, coupling and real operating conditions, so it genuinely reduces the vibration you have on site. A dominant amplitude at 1X running speed with a stable phase points to unbalance. A typical single plane fan balance takes 2–4 hours where access is straightforward.
What should the coupling (shaft) alignment tolerance be?
Alignment tolerance tightens with speed. Commonly accepted limits in practice are roughly 0.07 mm parallel offset and 0.07 mm per 100 mm angular deviation at 1500 rpm, and around 0.05 mm and 0.05 mm per 100 mm at 3000 rpm. Where the machine manufacturer specifies a figure, that figure governs. Because laser systems measure to 0.01 mm resolution, these tolerances are comfortably achievable; the dial indicator method typically stays around 0.05–0.1 mm.
What is soft foot and why does it matter?
Soft foot is the condition where a machine's four feet do not sit in the same plane — like a chair that rocks because one leg is short. When the foot bolt is tightened, the frame is distorted, bearing centres shift and the alignment result is destroyed. Soft foot must therefore be measured and corrected before shaft alignment. It is measured by loosening each foot in turn and reading how far it lifts; the generally accepted limit is 0.05 mm, and correction is made with stainless shims.
When should a wireless vibration sensor be chosen?
A wireless sensor is the right choice where the cost of running cable exceeds the value of the measurement, where access to the measuring point is difficult or hazardous, and where many items of medium-criticality equipment need monitoring. Typical applications are pumps, fans, blowers and gearboxes. Sensors such as Airius II offer up to four years of battery life at four measurements a day. Where very high sampling rates, simultaneous multi-channel measurement or a machine-stop signal are required, a wired continuous monitoring system is more appropriate.
What does a centralised lubrication system deliver?
A centralised lubrication system automatically dispenses the right amount of lubricant at the right time, eliminating both over- and under-lubrication. According to a study by a leading machinery manufacturer, roughly 50% of mechanical failures stem from insufficient or irregular lubrication. The system also removes machine downtime caused by manual greasing, reaches points that are otherwise hard to access, and extends the service life of critical components such as bearings, joints, guides and pins.
What does a real-time oil analysis sensor do?
A real-time oil analysis sensor continuously measures the electrochemical properties of oil at molecular level and reduces its condition to a single number. On Tan Delta sensors this value is the Tan Delta Number (TDN), where 1200 is clean oil and 0 is fully worn oil. Oil changes can then be planned on real condition rather than a calendar, and contamination or accelerated wear is spotted instantly. The delay of sending a sample to a laboratory disappears.
What is the ISO 18436 vibration analyst certification?
ISO 18436 is the international standard defining the competence of condition monitoring and diagnostics personnel. ISO 18436-2 is dedicated to vibration analysis and classifies personnel across four levels, Category I to IV. Category I focuses on data collection, II on intermediate analysis, III on advanced analysis and programme management, and IV on specialist subjects such as modal analysis and rotor dynamics. Certification requires training, an examination and a defined period of practical experience together; certification is valid for 5 years.
Which areas does Doruk CBM serve?
Doruk CBM is based in Menemen, İzmir and provides field service across Türkiye. Vibration measurement, on-site balancing, shaft alignment and training are delivered at the customer's plant. Scheduled periodic measurement programmes run in the Aegean, Marmara and Mediterranean regions, with project-based field work elsewhere. Product sales, service and calibration are available nationwide.
Which brands does Doruk CBM represent in Türkiye?
Doruk CBM is the authorised representative in Türkiye for SPM Instrument of Sweden (condition monitoring instruments, continuous monitoring systems and Condmaster software), Ciaponi of Italy (centralised lubrication systems) and Tan Delta Systems of the United Kingdom (real-time oil analysis sensors). It also runs ISO 18436 compliant vibration analysis training and certification programmes in partnership with SPM Academy.
Where should I start a condition monitoring programme?
Start with a criticality analysis rather than an instrument purchase. In order: (1) list the machine park and assess each item's downtime cost, redundancy and failure history; (2) focus on the most critical 10–20%; (3) define measuring points, directions and measurement setups for that equipment; (4) take a baseline measurement; (5) establish a regular route and set alarm levels. Training the team matters more than the choice of instrument: a team that cannot interpret the data will not produce results even with the best hardware.
Should I choose a continuous monitoring system or periodic measurement?
The choice is set by downtime cost and how fast the fault develops. Continuous monitoring is needed where the hourly cost of downtime is high, where there is no standby, where access to the measuring point is hazardous or impossible, or where a fault can progress into a failure between two measurements. For medium and low criticality equipment, a monthly or quarterly route measurement is sufficient and far more economical. Most plants use both: the most critical 5–10% continuously and the rest periodically.