During the past few years, many countries have put forward their national manufacturing strategies. Although these strategies are proposed and developed under different backgrounds, their common objective is to achieve intelligent manufacturing, which has the potential to revolutionise manufacturing industry and is being nurtured through national projects such as "Industry 4.0" in Germany, "Made Smarter" in the UK, "Industrial Internet" in the US, and "Intelligent Manufacturing" in China, etc. These projects promote a new manufacturing philosophy to guide the development of industrial manufacturing in a digital, intelligent and networked global environment, as well as upgrade the traditional manufacturing to intelligent manufacturing. With taking advantages of artificial intelligence and advanced manufacturing technologies, intelligent manufacturing connects all manufacturing facilities and enables physical processes and information flows to be available when and where they are needed across holistic manufacturing supply chains, this will benefit optimizing manufacturing resources, improving product quality, system productivity and sustainability, and reducing costs. Intelligent manufacturing has attracted intense attention due to the broad application of artificial intelligence and information science technology in manufacturing industry. In this study, 1370 papers in intelligent manufacturing are taken as data sources, which are retrieved from the Web of Science Core Collection Database between 1987 to 2017. The present paper aims to reveal the development status, the number of documents by leading countries, hotspots and trends of intelligent manufacturing by VOSviewer tool. Based on annual outputs and growth rate of literatures, the initial development stage (1987-1997), the stable development stage (1998-2012) and the rapid development stage (2013-2017) of intelligent manufacturing are proposed. On the whole, to date, China takes a leading position out of more than 100 countries or regions, followed by America and England. With more than 30 years of evolution, the connotation of intelligent manufacturing mainly goes through the process from digitalization to networking and then to intellectualization. In the recent research (since 2013), new enabling technologies for intelligent manufacturing have been developed, including Internet of Things (IoT), Big Data, Digital Twin (DT), Cloud Manufacturing, and Cyber-Physical System (CPS), which endow the manufacturing process with intelligence. For instance, IoT devices can communicate and interact with each other, and thus enable the real-time monitoring and dynamic control. Big data analytics together with AI can help to mine out potential rules, knowledge and patterns, in order to smart prediction, evaluation, optimization and decision-making. DT aims at constructing interactive virtual mirrors for physical assets and fusing both real and simulated data to give more insights. Cloud Manufacturing transforms manufacturing resources and manufacturing capabilities into manufacturing services, which can be managed and operated in an intelligent and unified way to enable the full sharing and circulating of manufacturing resources and manufacturing capabilities. These technologies can be combined with each other and greatly promote the innovation of manufacturing in design, production, operation and maintenance, etc. The findings presented in this study reveal the technical developing tendency and current hot topics in intelligent manufacturing and will facilitate scholars' investigation in the related fields, a comprehensive taxonomy of Intelligent Manufacturing can also be developed through analyzing the results of this review.
