MPI Bench Units


Medium Bench Unit

MPI Bench Unit

The MBU is a bespoke medium bench unit for performing MPI. The MBU includes AC current flow and magnet flow (FWDC) energising modes as standard with optional HWDC and FWDC current flows modes available.

The MBU is built around a sturdy 75x50x3mm RHS frame which includes an inking hose and under unit ink reservoir to allow for ink to be reused. The variable position head-stock can be moved via a front mounted wheel and pneumatically clamp using a foot peddle to grip components between the U4 type Copper gauze contact pads - The diameter of the contact pads can be made to requirement. The MBU is supplied with heavy duty energising foot pedal and fully calibrated with the relevant paperwork as standard.

MBU's can be built to have a maximum outputs from 2,000A up to 4,000A depending on the power required. The unit can be tailored to customer requirements to achieve the most economical solution to customer needs.

Case Studies

MBU 2000: Crack testing crankshafts - Click here

Control System

Johnson & Allen MPI Bench Units are built around one of three control systems - The Manual System, Start System and the Plato 3 System.

The Plato 3 System is recommended for MBU builds.

  Manual System Start System Plato 3 System
Manual Current Regulation
Automatic Current Regulation  
Shot Timer Optional

Automatic Demagnetising

Quick Break
(for FWDC)
Quick Make    

Button Press Mode Change Over

Optional Optional
Programmable Job Sequences    
Data Acquisition & Monitoring    
Code Loader (Barcode Scanner)    


Plato-3 is a control and monitoring system for MPI bench units and power packs with an emphasis on data recording and traceability.

Click here to read more about the Plato 3 System

Plato-3 includes all the features found in the earlier Plato-2 System like auto-regulated current (dial-an-amp), variable shot timer and programmable job sequences but brings to the table new features, full data acquisition and monitoring and a more intuitive interface displayed on a colour monitor.

UV Inspection Booth

For fluorescent MPI processes the MBU can include a bespoke UV Inspection Booth to reduce ambient light below the 20 Lux demanded by most MPI standards. UV Inspection Booths are usually free standing and fitted with both UV lights and white lights to give adequate background UV light when inspecting with the option of white light for safely loading components and maintenance.

UV Inspection Booths are built around a sturdy steel frame and panelled with either a PVC canvas or steel sheet. Most UV Inspection Booths also incorporate a number of fans to remove heat and prevent build-up of chemical vapours within the booth. Component doors are also common and can be either manual or pneumatically operated.

MBU2000 Mags Bench with Inspection BoothMBU2000 Mags Bench with Inspection Booth

Bench Accessories

The MBU can be supplied with a wide range of accessories including threading bars, rigid fixed coils, headstock mounted ‘V’ brackets, mini-jigs and hand-held UV Inspection Lights to aid in inspection processes.

Quality UK Construction

Johnson & Allen pride itself on high quality design and construction which is why the power transformers and coils used in the MBU are wound, built and extensively tested in-house before they are installed. All Johnson & Allen bench units are designed and manufactured by our experienced team in Sheffield.

Product Data

Input Voltage 230V
Frequency 50Hz
Phase Single
Energising Modes AC (Standard)
Mag. Flow (Standard)
HWDC (Optional)
FWDC (Optional)
Current Flow Output 0 - 5000A RMS AC
Mag. Flow Output 23,000 Amp Turns
Metering Digital
Max. Component Length 1000mm


Talk To Our Team

As with all bespoke builds Johnson & Allen recommend customers contact our technical sales department to discuss their precise needs first. Our experienced team can recommend the most economical way to achieve customer requirements.

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