Fibre based low coherence interferometry for in-process control of electrochemical machining processes

Lead Research Organisation: Loughborough University
Department Name: Wolfson Sch of Mech, Elec & Manufac Eng


In-situ control and in-line monitoring of manufacturing processes are complex and difficult to implement. For example, manufacturing processes are often fast paced, meaning any real-time monitoring system must be flexible and able to analyse data quickly enough to implement decisions. In addition, manufacturing environments are non-ideal with varying external factors affecting the state of the system with time. This is especially true in electrochemical machining, which takes place within a bath electrolyte liquid, or within a small jet of electrolyte, in the case of electrolyte jet machining. Making high precision measurements in this environment, and within the compact operating space of the processes, is challenging and currently there is no available measurement technologies to achieve this.

Low coherence interferometry is an established promising technique, which uses light to capture distance information within a system. It is possible to deploy the light from a bare tipped fibre optic and allowing data to be captured from highly space constrained environments. However, which using a fibre without the addition of optics, the performance of the sensor is greatly reduced. Current systems are limited by the standoff distance required to ensure accurate measurements are possible and the type of light source used. In addition, systems are limited by their operation, performance, cost and packaging within the manufacturing machinery.

The purpose of this research will be to:
Analyse existing OCT interferometry systems to understand their limits when applied to in-situ measurements in challenging manufacturing processes.
Support the further development and extend the operation of the current prototype system created as part of EPSRC grant EP/M020746/1
Develop an approach to extend the standoff distance and, as such, the working range
Develop a data collection and analysis methodology to allow continuous scanning methods to be used for extended operation.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509516/1 01/10/2016 30/09/2021
1965823 Studentship EP/N509516/1 01/10/2017 31/03/2021 Thomas Hovell
Description Produced a low coherence interferometer sensor able to perform surface topography measurements in air and water environment with high levels of accuracy and repeatability.
Performed profilometry measurements with the fibre sensor situated within a high speed liquid jet, demonstrating potential for simultaneous measurement and flushing of debris resulting from machining processes
Exploitation Route The results of this work could be taken forward by manufacturers of high-value small scale components looking to machine and verify features within the micrometre to millimetre range. In particular use of the sensor operating in a liquid jet to simultaneously clear debris from machining operations such as coolant fluid and metal filings to ensure high integrity measurement results to use for verification of tolerance adherence on-machine.
Sectors Manufacturing, including Industrial Biotechology