# The Analysis of Key Technologies for Sustainable Machine Tools Design
## 1 Introduction  
### Sustainable Manufacturing and Design  
Sustainable manufacturing has been widely recognized as the main development trend of industries for three decades with the benefit on lower resource and production costs, easier employment and increasing safety because manufacturing industry impacts the sustainability performance of manufactured products in different life stages [1]. Thus, with incoming requirements for sustainable dimensions, design and manufacturing engineers should take into account sustainability in their activities. Each product-integrated manufacturing process has environmental impacts including energy and materials, while life cycle thinking should involve each stage of the product's life which consumes energy and other resources and generates waste and emissions [2]. Design and process planning have great flexibility in making decisions for machine and factory operation [3]. Therefore, this paper addresses how to design sustainable machine tools (MT) utilizing detailed approaches in order to achieve the goal of sustainable manufacturing and production. Additionally, sustainable manufacturing needs manufacturing industries to consider economy efficiency, environment and society benefits through process planning utilizing advancing manufacturing technology to promote a product's competitive position. Hence, the industrial sector needs to select more sustainable machines, such as high energy efficiency and high resource efficiency, low waste, and so on. In the past, the eco-design of machine tools has been well studied and addresses only the environmental aspect especially energy consumption in use stage [4; 5]. Although the energy aspect of a machine tool in the use stage was integrated into the design process, there is lack of comprehensive methods to define sustainable machine tools in the early design stage. The research objective is the machine tool itself, not the products machined on the machine tool. It is well known that machine tool design and subsequently the machine tool operators play an important role in most industrial fields, as it has been used widely in factories as the mother machines. The machine tool industry's directives and standardizations involving a partial sustainability dimension have already appeared. For example, it is worth noting that the European Union develops constantly standards and policies related to energy-using products, such as Directive 2009/125/EC [6] related to energy consumption standards for machine tools and related machinery products, and Directive 2005/32/EC [7] involving eco-design of energy-using products. The Self-Regulatory Initiative promoted by the European Association of the Machine Tool Industries (CECIMO) in European Union indicates that manufacturers should improve the ecologic footprint of manufactured MT. This regards eco-design as an effective action to enhance sustainable design performance and competitiveness in the long life of the MT industry to achieve the aims of increasing energy efficiency whilst taking into account the technical characteristics of machine tools. Moreover, CECIMO is also operating the 'Blue Competence Machine Tools' [8] project to promote utilization ratio for energy and other resources of MT and customers. Additionally, ISO 14955-1:2017 [9] proposed the application of eco-design standards of MT. The directives mentioned above are guidance for machine tool industries, but not mandatory requirements. In future, MT builders should supply some essential data related to sustainability performance except function and purchasing cost. As regards the environmental realm, most research focuses on energy efficiency, including the energy efficiency measures in the use stage [4; 10; 11], the energy map of the main components [12] such as main spindle, driving system; second, on resource efficiency, involving raw material, water, cooling and lubricant fluids [13; 14]; third, on carbon emissions [15].