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HS Sensors

Pulp and paper: machine vibration monitoring

A paper machine is a long line of rolls, cylinders and drives running non-stop in moisture and steam. Regular vibration measurement on pumps, fans, gearboxes and rolls makes it possible to detect wear and looseness in advance and to use shutdowns for planned repairs.

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Pulp and paper
© Hansford Sensors

What fails most often

Paper and pulp production is a continuous process. A failure of a stock pump, dryer fan or section drive gearbox can end in a web break or a machine stop, and after a restart it takes time for the product to return to specification. An unplanned stop means lost production and paper out of specification, so planned shutdowns are prepared carefully — and machine condition monitoring data helps to decide what needs to be done during them.

Different conditions in each section

In the forming section, sensors are sprayed with water and cleaning agents; in the press section, they work under heavy load and in constant moisture; and in the dryer section, at high temperature and in steam under the hood. Stock preparation adds pumps and agitators handling a thick fibre suspension, and the finishing area adds paper dust.

There are many measurement points on one machine, and a large share of them are on the drive side, behind the machine frame or under guards. This is why paper mills widely use permanently mounted sensors cabled to junction boxes and switch boxes, from where the signal goes to a data collector or an online monitoring system.

Typical machines

Stock and circulating water pumps
cavitation, impeller unbalance, bearing damage
Fans and blowers for drying and hood ventilation
unbalance, misalignment, bearing wear
Section drive and conveyor gearboxes
gear tooth wear, inadequate lubrication, bearing damage
Motors and drives
rolling-element bearing damage, coupling misalignment, mounting looseness
Press section
mechanical looseness, uneven roll pressure, roll bearing damage
Drying cylinders and guide rolls
damage to bearings operating at high temperature
Pulpers and refiners
unbalance, bearing damage, mechanical looseness

From the machine to the monitoring system

  1. 01Machines in this industry

    Stock and circulating water pumps, fans and blowers for drying and hood ventilation, section drive and conveyor gearboxes and others — measuring point on the bearing housing.

  2. HS-104R — Low-power triaxial accelerometer, top exit, PUR cable

    02Sensor

    An IEPE accelerometer or a 4–20 mA sensor converts vibration (and often temperature) into an electrical signal.

    Industrial IEPE accelerometers
  3. HS-AA018 — Inline adaptor

    03Signal

    A cable with the right connector and a junction box carry the signal from many measuring points to the system.

    Cables and connectors
  4. HS-570-60 — Power supply module

    04Monitoring

    PLC, DCS, an online system or a data collector: trends, alarm thresholds and diagnostics before a failure happens.

    Vibration systems and switches

How to choose the measurement

Wet sections

In places constantly sprayed with water, HS-100 accelerometers with an integral cable work best: this eliminates the connector, which in a wet area is often the weakest point of the installation. The series includes top exit and side exit versions, and the IP rating depends on the cable type — check it in the datasheet before ordering.

Press and dryer sections

For presses and drying cylinders, HS-100 versions with a 2-pin MS connector are available, with top or side exit — depending on the space above the bearing housing. Such a sensor works with a separate cable assembly, which can be run in protective conduit, and the sensor alone can be replaced without dismantling the installation. According to the manufacturer, HS-100 operates at up to 150 °C; in the dryer section, check the temperature at the mounting point and the limit of the selected cable and connector.

Junction boxes and switch boxes

Sensor cables are connected to multi-core cables in HS-JE waterproof junction boxes, available in stainless steel, painted steel and polycarbonate enclosures. Multi-channel HS-SE switch boxes provide a convenient reading point for the data collector — for example, separately for the tending side and the drive side.

Integration with the control system

On pumps, fans and motors where continuous monitoring of the vibration level is sufficient, HS-420 sends a 4–20 mA signal proportional to vibration velocity directly to the paper machine DCS. The trend is then visible to operators and maintenance staff without a separate diagnostic system.

Mounting

The HS-AS mounting studs and pads provide a rigid connection between the sensor and the bearing housing. The Quick Fit version allows the sensor to be removed quickly, e.g. when a roll is replaced, and refitted in the same place, which keeps trends comparable.

Recommended versions

All products for this industry (55)

Product groups for pulp and paper

Industry questions

Can a sensor be mounted in a location constantly sprayed with water?

Yes, if you choose a version with an integral cable and a suitable IP rating, as given in the datasheet. Route the cable so that water runs away from the sensor, and take it to a junction box outside the spray area. Use connectors in the wet area only if the selected version provides the required sealing.

How do I measure the vibration of drying cylinder bearings?

Mount the sensor on the bearing housing, on a stud, in the radial direction. Temperature is critical: according to the manufacturer, the HS-100 operates up to 150 °C, but the cable or connector may lower the limit for a specific version — check it in the datasheet. A version with a 2-pin MS connector and a separate cable makes it easier to replace the sensor under the hood later.

Route-based measurements or online monitoring in a paper mill?

Most auxiliary machines, such as pumps and fans, can be covered well by route-based measurements with a data collector via switch boxes. Online monitoring is worth considering for machines that are critical, hard to access, or on which damage develops quickly. In the DCS, 4–20 mA transmitters complement both approaches with a continuous trend and alarms.

Further reading

Describe your paper machine

Tell us which sections and auxiliary machines you want to monitor, what conditions they work in and whether the signal is to go to a data collector or to the DCS. We will help you put together the sensors, cables and switch boxes.

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