Optics and Lasers in Engineering 45 (2007) 1010–1017 Fabrication of smart cutting tools with embedded optical fiber sensors using combined laser solid freeform fabrication and moulding techniques Hamidreza Alemohammad, Ehsan Toyserkani à , Christ P. Paul Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ont., Canada N2L 3G1 Received 16 February 2007; received in revised form 10 April 2007; accepted 11 April 2007 Available online 15 June 2007 Abstract To realize the concept of smart tools, embedding of fiber optic sensors in the metallic structure of a cutting tool with combined laser solid freeform fabrication (LSFF) and moulding is presented in this paper. Metallic parts with embedded optical fiber sensors are capable of monitoring physical parameters like force and temperature. These sensors are advantageous relative to other conventional electric and electromagnetic sensors due to their light weight, immunity to external electromagnetic fields, small size, long-term durability, and long- range linearity. In the present work, the optical fibers (e.g., fiber Bragg grating sensor, single-mode fiber optics) are moulded under tensile forces within a mild steel casing filled by Sn–Pb to fabricate a protective layer around them. Afterwards, LSFF is utilized to deposit tungsten carbide reinforced in cobalt (WC–Co) on the surface of the mild steel component. The performance results, in which the sensor exposed to a light bandwidth, show that the maximum light power loss after embedding is about 21% implying that the fiber is not damaged during the embedding process. Also, the sensor output has a linear characteristic under compression loadings indicating that the debonding of the fiber from the protective layer is not probable. The produced samples are examined by scanning electron microscopy and X-ray diffraction to assess the physical properties of the tool. Microstructural images reveal no cracks and porosity around the fiber indicating a good bonding between the fiber and the surrounding media. Material characterizations of the manufactured tool are also discussed. r 2007 Elsevier Ltd. All rights reserved. Keywords: Smart cutting tools; Fiber optic sensors; Laser solid freeform fabrication; Tungsten carbide reinforced in cobalt 1. Introduction In situ measurement of loads applied to tools (e.g., cutting, drilling, mould and die) is essential to high precision machining and health monitoring. Tool health monitoring and precision machining necessitate real-time awareness of the applied thermal and structural loads. Using conventional sensors attached on the surface of the tools, one can measure the physical loads applied to the tool. However, the measurement is only limited to external surfaces. Embedded sensors within the metallic structure of tools can monitor the physical parameters not accessible by ordinary sensors. The signals from the embedded sensors can be processed to obtain the thermal and/or structural loads applied to the tool in-service. The obtained data can be used as feedback signals in a real-time control system to improve the performance of the tool. They can also be used for failure detection in cutting tools in-service. Among all available sensors, optical fibers can be effectively used to monitor thermal and structural loads. Compared to conventional electric and electromagnetic sensing devices, optical fiber sensors, made of silica ðSiO 2 Þ, are advanta- geous. They have light weight, small size, long-term durability and long-range linearity. Moreover, they are robust to external electromagnetic fields and disruptions [1]. These capabilities prompt the development of a technique to embed optical fibers inside metallic structures to realize the concept of smart tools. Embedding of optical fibers inside concrete and compo- site materials for structural health monitoring has been ARTICLE IN PRESS www.elsevier.com/locate/optlaseng 0143-8166/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.optlaseng.2007.04.006 à Corresponding author. Tel.: +1 519 888 4567x37560; fax: +1 519 888 4333. E-mail address: etoyserk@uwaterloo.ca (E. Toyserkani).