Negotiations regarding global climate change have emphasised on the concept of sustainable manufacturing for the conclusive growth for all. Globally, the aim of sustainable manufacturing is to increase the efficiency of the manufacturing processes by employing green manufacturing practices (GMPs) having negligible impact on environment and to utilise GMPs to have zero production defects, thus leading to both economic and environmental benefits. Manufacturing industries dealing with metal machining are important from a socio-economic point of view. Among available metal machining operations, the turning process is widely favoured and has a lion’s share in cutting and shaping of metal.
Although technical advancement in metal machining makes the turning process highly efficient, nevertheless, some social and environmental aspects are associated with it that continue to pose serious concern and probably have negative consequences on the surroundings. The metal machining process generates a lot of waste in the form of byproducts in solid, liquid and gaseous forms which pose a threat to our environment as well. Even though cutting fluids enhance the metal removal operation and ensure surface quality, they have a harmful impact on human health and environment.
Cutting fluids, when mixed with metal chips, become sludge that is hard to separate and the accumulation of which becomes a breeding ground for pathogens that are dangerous to man, machine and material. This issue not only has an effect on health but creates concerns about safety too. It also affects in terms of macroeconomics because a heavy cost is associated with their disposal which in turn adds to the production cost. Further, the high density of electric energy consumed while doing metal machining is also an indirect environmental concern, adding up to the production cost.
To tackle health and environmental risks along with retaining efficiency-based competitiveness, various ecological-friendly, sustainable, and green manufacturing technologies and strategies are evolving with a vision of incorporating sustainable manufacturing approaches. Bio-machining is one amongst such green manufacturing techniques in which a microorganism is used as a cutting tool for the purpose of metal removal from a metallic work piece. This is a carbon-neutral process leading to decrease in carbon footprint. The bio-machining process depends on the enzymatic activity of microorganisms to machine metal surface which can replace the use of conventional metal-cutting tools and hazardous fluids.
Further, microorganisms used as cutting tools are self-cultured and self-renewable, thus making this a sustainable, cost-effective and energy-efficient green manufacturing process. In this context, a study was conducted in collaboration with Tanveer Singh Jhajj (PG student at GNDEC, Ludhiana) & Dr Amanpreet Kaur Sodhi (faculty at GNDEC, Ludhiana) to identify the potential of fungus, i.e.,. Aspergillus niger by considering the physiochemical parameters such as shaking rate, pH, microbial concentration and temperature for bio-machining of EN 19 alloy steel due to its high wearing capacity with applications in strategic places like aircrafts, tanks, axle of army trucks, etc. For machining of EN-19 alloy steel, dry machining has been considered more favourable over wet machining.
However, the tooling cost of dry machining is higher, which is not good from an economic point of view. Simply put, the machining of this material is an important consideration & efforts have thus been made to explore the potential of microorganism in a sustainable way. The study, however, reflected continuous weight reduction of the work piece, proving the machining effect on alloy steel produced by Aspergillus niger and highlighted the need for optimisation of physiochemical parameters in order to further scale up the process for precision machining applications in the near future.