Ring Metal Detectors For Process Control Ring Detectors and Product Effect

As single stand-alone components, our ring sensors are also used in many other ways. They can be used , for example, for counting parts, i.e., screws or bolts, as discharge monitoring devices for stampings, for detecting broken wires. The output signals of ring sensors can be used for controlling, signaling or evaluating events in many different industrial processes. We offer a wide range of ring sensors which differ in design, sensitivity and/or kind of output signals. We also offer ring detectors that can effectively reduce product effect.

Applications

At the top of the metal detection scale, is the M-Pulse generation of metal ring detectors. To reach higher levels of sensitivity and reliability than standard analog and digital models, the M-Pulse design uses a special high capacity digital evaluation software originally designed for use in the food processing industry. Because of rising standards in the plastics industry, these ring detectors are also ideal for use for detecting metal in the plastics industry.

Function and Limitations

A typical M-Pulse RG ring detector includes the following components:

  • A Transmitter Coil - for producing a high frequency magnetic field.
  • Two Receiver Coils - that receive signals generated by the magnetic field.

Ring Metal Detectors For Process ControlOnce the ring detector is switched on, the magnetic field capacity of the transmitter coil is adjusted so that both receiver coils receive the same identical signal. This balances the system as metal moves through the magnetic field of the metal separator. The modification of the magnetic field changes the current in the receiver coil which becomes unbalanced and is called an electromagnetic process.

The degree of change of the magnetic field is the direct result of the changes in the magnetic and electrical properties of the metallic particle. While bigger metallic particles generate greater currents than smaller particles, magnetic metals like steel cause greater currents than non-magnetic metals like aluminum. The modified current is measured, processed and evaluated by the metal detector and its software.

Product Effect Compensation

Choosing the right ring detector depends on how well it can compensate for the natural conductivity found in plastic and food products. To compensate for these natural occuring product effects, the M-Pulse RG ring detector is equipped with software that minimizes them. Product effect compensation is critcal in products with carbon or salt, i.e., black plastic granulate, meat and other salt based foods. Without this software, standard and digital ring detectors can only lower their sensitivity levels which allows them to detect only larger metal particles allowing smaller particles to make it through. To a lesser degree, choosing the right ring detector also depends on whether the product is free falling or packaged, and the size, shape and orientation of the metal contaminants with respect to the detection coil.

Metal Free Zones (MFZ)

The active magnetic field surrounds the complete ring housing. That means the magnetic field is not limited to the length of metal housing. In front and behind the free ring opening bigger metal parts will also be detected. To assemble the ring detector properly, the user must prevent that conductable part of the metal from entering certain areas called metal free zones (MFZ). In this areas plastic parts or other non-onductable adapters are allowed. This explains why the Protection Tube Material inside the ring detector is usually made of plastic.

It is important to know how large the metal free zone should be. Metal free zones for moving metal parts are also often larger than metal free zones for nonmetallic moving parts. Problems can arise if the user installs a metal shaft, a metal flap, a rotating metal part or any other static metal construction inside a metal free zone. The ring detector will generate a false report of metal and the user will be tempted to lower sensitivity levels to avoid any false reports. Unfortunately, when the sensitivity level is lowered to compensate for these false reports, some metals can make it through undetected. Correct sizes of the metal free areas can be found in the table below.


Model Name MPULSE RG 25 MPULSE RG 35
Mechanical details    
Installation height 80 mm 98 mm
Nominal width 25 mm 35 mm
Material of the ring Aluminum casting Aluminum casting
Material of protection tube [optional] Teflon, Polyethylene, POM
Protection class of the detector IP 65

Application Conditions
Metal free zone for flexible metals 40 mm above and under the detector 60 mm above and under the detector
Metal free zone for non flexible metals 25 mm above and under the detector 35 mm above and under the detector
Max. detection speed 2 m / sec
Max. housing temperature 0-50° C

Sensitivity Adjustable Maximal [no product effect assumed]
In the center of detector [Fe/Ne/VA-bullet in mm} app. 0.1/0.13/0.15 app. 0.15/0.2/0.25
Sensitivity adjustable by LC - display-keyboard
Mode of operation of evaluation electronics digital
Mode of operation of ring detector Transmitter - Receiver

Main Connections
Operational voltage 230 V/50 Hz (others at inquiry)
Compressed air supply 4-6 bar, filtered, free of water and oil
Power consumption <40 VA
3 m Connecting cable L1/N/PE* 1.5 mm2
Operating voltage Ub 85-274 V/47-440 Hz or 110-340 V DC

For more technical information takes it please the chapter accessories under the point M-Pulse control electronic.

Mechanical details
Installation height 98 mm
Nominal width 50 mm 70 mm 100 mm
Material of the ring Aluminum casting
Material of protection tube [optional] Teflon, Polyethylene, POM
Protection class of the detector IP 65

Application Conditions
Metal free zone for flexible metals 80 mm above and under the detector 100 mm above and under the detector 120 mm above and
under the detector
Metal free zone for non flexible metals 50 mm above and under the detector 70 mm above and under the detector 100 mm above and
under the detector
Max. detection speed 2 m / sec
Max. housing temperature 0-60° C

Sensitivity Adjustable Maximal [no product effect assumed]
In the center of detector [Fe/NE/VA-bullet in mm} app. 0.25/0.35/0.4 app. 0.4/0.5/0.6 app. 0.5/0.65/0.7
Sensitivity adjustable by LC - display-keyboard
Mode of operation of evaluation electronics digital
Mode of operation of ring detector Transmitter - Receiver

Main Connections
Operational voltage 230 V/50 Hz (others at inquiry)
Compressed air supply 4-6 bar, filtered, free of water and oil
Power consumption <40 VA
3 m Connecting cable L1/N/PE* 1.5 mm2

Model: MPULSE RG 25 Model: MPULSE RG 35
Model: MPULSE RG 50 Model: MPULSE RG 70
Model: MPULSE RG 100

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Plastic Process Equipment


Plastic Process Equipment

23 Spielman Road, Fairfield, New Jersey, USA, 07004-6155
Tel: 973.227.0700 ~ Fax: 973.227.7307 ~ Email: