Advancing Environmentally Conscious Machining

Abstract

Modern machine tools now consume far more energy than their predecessors, a contradiction in terms since manufacturing organisations expect machining to be carried out in the most sustainable and cost effective way. The goal for environmentally conscious manufacturing is to consume minimum energy and produce minimum atmospheric emissions, liquid and solid waste. Dry machining is obviously the most ecological form of metal cutting as there are no environmental issues for coolant use or disposal to consider. This research was implemented in an industrial situation in a local small to medium sized enterprise (SME) in Western Australia to determine the technical, economic and environmental benefits of the replacement of traditional flood cooling with Minimum Quantity Liquid (MQL). The use of MQL and air reduced the greenhouse gas emissions and eco-toxicity associated with the disposal of the contaminated liquid. It was found that this alternative cooling method increased the performance of the metal cutting operation.

A review identifying the effectiveness of minimum quantity lubrication (MQL) during conventional machining

“…(2) The lubricating film layer provided by vegetable oils, being intrinsically strong and lubricious, improves workpiece quality and overall process productivity reducing friction and heat generation. These advantages were reflected in various studies on milling [41], drilling [42,43], turning [40,44,45] and grinding [46]. As for synthetic esters, similar properties were observed including high boiling temperature, flash point and low viscosity, thus leaving a thin film of oil on the workpiece which aids in corrosion resistance [38].…”

Environmental Analysis of Sustainable and Traditional Cooling and Lubrication Strategies during Machining Processes

“…The bolt has a length of 200 mm and a diameter of 42 mm. Besides, the used bolt is manufactured by local small to medium-sized enterprises (SME) in Western Australia [39]. The conducted LCAs in this paper cover the machining a single AISI 4043 bolt.…”

“…The information included: cutting energy, pumping energy, compressor energy, the quantity of coolant, and tool weight reduction. SME cutting energy and tool weight reduction information were excluded during the development of the presented LCAs, because their provided amounts are influenced by CFs [39] used. In regard to the pumping energy, TFC consumed 5.124 × 10 5 kWh per bolt, while the MQL cooling technique consumed 0.051 kWh during CFs pumping and air compressing.…”

“…In regard to the pumping energy, TFC consumed 5.124 × 10 5 kWh per bolt, while the MQL cooling technique consumed 0.051 kWh during CFs pumping and air compressing. Although MQL uses approximately 7.6% of the amount of cutting fluid in TFC, it consumes considerably higher energy than TFC, due to the energy consumed by MQL's air compressor [39]. Figures 7 and 8 display the impacts of CF strategies on four damage categories, which are: human health, ecosystem quality, climate change, and resources.…”

The Experimental Investigation of Using Thermography Inspection for Dry Turning Process Diagnosis

“…Using coolants and lubricants during machining processes increases costs, has negative environmental impact and causes workers' health hazards. Thus, there is a general move towards dry machining [4,7]. Considering above it is increasingly important to understand how machining temperatures are affected by the process parameters: cutting speed, feed rate, tool geometry, and by other factors such as tool wear and the characteristics of workpiece material (e.g., thermal diffusivity and hardness).…”