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In many applications in the metalworking industries, mass production of parts with holes possessing critical finish requirements for precision assembly operations demands tolerances in the working range of IT7 to IT5. However, this may not be achieved with regular twist drills, and further finishing processes such as reaming is normally required. To perform reaming, the workpiece needs to be previously drilled, so that two different cutting tools are needed and twice as much time is needed to machine compared with workpieces that need to be drilled, which in turn affects productivity and competitiveness. Therefore, any investment in the production of tools and techniques aiming to reduce the machining time of close tolerance holes, and lower tool wear rates and at a lower cost, will receive special attention from the machining sector. In this context, this paper presents technical and economic analyses of two manufacturing systems in drilling (drilling specially designed drill and regular drill with reamers) of compacted graphite iron (CGI) workpieces. The technical analysis was based on the tool wear mechanism, hole quality, and machining time, whereas the economic analysis was on total machining cost for use of specially designed drill and regular drills followed by reamers. Results showed lower wear on the specially designed drills compared with reamers. Also, the finish and dimensional deviations were similar to those obtained with reamers. Up to 40% of reduction in the machining time was achieved by using the specially designed drill, which resulted in a 57% reduction of the total cost. [ABSTRACT FROM AUTHOR]

Large quantities of coolant–lubricants are still widely used in the metal working industry, generating high consumption and discard costs and impacting the environment. This paper presents the evaluation of the performances of the various machining environments (dry, conventional wet and MQL technique) applied in hard turning of the AISI 4140 high-strength low alloy steel with coated mixed ceramic (CC6050) in terms of surface roughness, cutting force components, and tool wear. For this purpose, a number of machining experiments based on statistical four-factor (cutting speed, feed rate, depth of cut, and cutting radius) and hybrid-level factorial experiment designs uncompleted with a statistical analysis of variance were performed. The results indicate that the resulting cutting force obtained with the MQL machining process significantly improved when compared with other machining processes. For example: FRMQL ≈ 1.08 FRdry and FRwet ≈ 1.37 FRdry. Then, the RSM was utilized to define the optimal machining parameters. Finally, the ranges for best cutting conditions are proposed for serial industrial production. [ABSTRACT FROM AUTHOR]

It is possible to create value with less environmental impact through the adoption of Lean and Green manufacturing concepts and tools. This paper proposes a Lean-Green model based on the application of the Single Minute Exchange of Die (SMED) combined with Carbon Footprint (CF) to analyze eco-efficiency of a machining center in a case study in Brazil. The novelty of this paper was the proposal of a Lean-Green model based on ecoefficiency indicators to measure performance of production systems toward a cleaner production. The developed Lean-Green model should be used by companies with low-capacity of production due to restrictions of machine availability. The case study was organized in five different scenarios by varying machine tools, workers and workpieces. First, the SMED tool was applied in the setup activities and gains of reduced idle times were up to 88%. CF results were reduced up to 81% after applying the SMED tool on each scenario. Lastly, an eco-efficiency set of indicators were used to combine results of SMED and CF, and results of eco-efficiency were 3% higher even with higher CF values after converting setup saved time into productive time. To achieve such results simple improvements were performed in the machining center, through the standardization of work and the study of time and methods for setup activities, showing that the proposed Lean-Green model could be also adopted by other companies to create value with less impact. [ABSTRACT FROM AUTHOR]

A review of advances in the use of lubrication techniques during machining operations as well as the application of state-of-the-art nanofluids in machining is presented in this research article. A brief review of the available literature on the environmental impact and the health hazards associated with metal working fluids is also included. The performance and drawbacks of different techniques are discussed in terms of machining parameters and output variables. The review of different lubrication techniques finally ends up in the favor of minimum quantity lubrication and cooling technique as a potential alternate to flooded and conventional cooling conditions in different machining processes in terms of dealing with the ecological, social and human health concerns and the finances coupled with the use of metal working fluids in machining processes. [ABSTRACT FROM AUTHOR]

In the beginning, metalworking fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, metalworking fluid formulation became more complex. There are now several types of metalworking fluids in the market and the most common can be broadly categorized as cutting oils or water-miscible fluids. In this paper, attention is focused on recent research work on formulation and application of vegetable oil-based metalworking fluids in turning process. In addition, the performances of various vegetable oil-based metalworking fluids based on some process parameters such as thrust force, surface roughness, temperature developed at the tool chip interface, and tool wear during turning process using different tool materials were highlighted. [ABSTRACT FROM AUTHOR]

The physical stability of emulsions can be related to changes in the droplet size distribution over time. Stability control of emulsions used as metal working fluids is an important factor for the machining industry due to the decreased performance of aged and broken emulsions. Results of turbidimetric spectra measurements of metal working fluids for process control purposes and emulsion stability monitoring are discussed. Metal working emulsions were artificially destabilized by admixing salts which resulted in droplet coagulation. The destabilization process was investigated by measuring the droplet size distribution and the turbidity spectra over time. The results were evaluated based on quantitative criteria proposed in the literature. The applicability of these criteria to evaluate metal working fluids during machining operations is discussed. [ABSTRACT FROM AUTHOR]

In the modern metalworking industry, production moulds often have complex geometry, with undercut regions, small corner radii, sharp edges, deep cavities, or large cores. Conventional manufacturing process chains to machine these complex features are often lengthy and inefficient due to multiple steps. This article presents current results obtained through industry projects and experimental work using 5-axis high-speed machining with high-end CAD/CAM systems to improve process efficiency. Cost optimisation and lead time shortening can be clearly shown. This is of particular importance for South African manufacturing companies, where multi-axis HSC technology - although not totally unknown - is significantly under-used. [ABSTRACT FROM AUTHOR]

Metalworking fluids (MWFs) are complex mixtures of chemicals and are indispensable materials in industry. They are used as cooling and lubricating agents in different machining process such as grinding, milling, and cutting. The quality of MWFs is affected by physical, chemical, and microbial contaminates. In particular, MWFs are highly vulnerable to microbial contamination, which may act both as potential pathogens and deteriorgens. Microbial contamination is of major concern due to potential health hazards such as skin dermatitis and hypersensitivity pneumonitis. The contaminated MWFs can exhibit high degrees of microbial loading, ranging from 10 to 10 colony-forming units (CFU)/ml. Wide varieties of microorganisms are reported to colonize MWFs. Traditional culturing techniques are not only laborious and time consuming but also underestimate the actual distribution of the microorganisms present in the contaminated MWFs. Therefore, rapid molecular methods such as real-time PCR and fluorescent in situ hybridization are implemented to monitor the microbial load. In industry, biocides are presently used to control microbial contamination. However, it has its own disadvantages and therefore, in recent years, alternative methods such as UV irradiation were evaluated to reduce microbial contamination in MWFs. Microbes inhabiting the MWF are also capable of forming biofilm which is detrimental to the MWF system. Biofilm is resistant to common disinfectant methods, and thus further research and development is required to effectively control its formation within MWF systems. This review is intended to discuss the overall microbiological aspects of MWF. [ABSTRACT FROM AUTHOR]

Respiratory problems are observed in machinists using soluble metalworking fluid (MWF). Evidences suggest that these problems could be related to the aerosolized microorganisms and their byproducts from MWF. To establish MWF aerosol exposure thresholds and to better understand their effect on human health, these aerosols must be fully characterized. This article evaluates airborne microorganisms and aerosols from soluble MWF in the working environment. Air quality parameters (endotoxin levels, culturable airborne microorganisms, fluid mist, inhalable dust and air exchange rates) were evaluated at 44 sites, in 25 shops in Quebec, Canada. Microorganism concentrations were also measured in MWF. Culturable airborne bacteria concentrations were low, ranging from 1.2 × 101 to 1.5 × 103 CFU (colony forming units) m- 3, even for metalworking fluid highly contaminated by bacteria (up to 2.4 × 109 CFU mL- 1). Inhalable dust varied between < 0.1 to 2.6 mg m- 3, while air exchange rates were mostly below the standard (4 h- 1) for this type of workplace, between 0.6 to 14.2 h- 1. Only nine of 44 sites respected the suggested minimum value for air exchange rates. Fluid mist ranged from 0.02 to 0.89 mg m- 3, which is below the threshold limit value (TLV) (ACGIH) of 5 mg m- 3. Airborne endotoxin concentrations ranged from undetectable to 183 EU m- 3 (endotoxin units), showing no correlation with airborne microorganisms or inhalable dust. Most workstations respected the suggested minimum values for fluid mist and showed low concentrations of airborne endotoxin, culturable microorganisms and inhalable dust despite fluid contamination, even when air exchange rates were below the recommendations. Airborne Pseudomonas pseudoalcaligenes was recovered from many sites at significant concentrations. Health-associated risks following exposure to this microorganism should be further investigated. [ABSTRACT FROM AUTHOR]

There are approximately 1.2 million workers exposed to metalworking fluids (MWF), which are used to reduce the heat and friction associated with industrial machining and grinding operations. Irritancy and sensitization potential of 9 National Toxicology Program (NTP) nominated MWFs (TRIM 229, TRIM VX, TRIM SC210, CIMTECH 310, CIMPERIAL 1070, CIMSTAR 3800, SYNTILO 1023, SUPEREDGE 6768, and CLEAREDGE 6584) were examined in a combined local lymph node assay (LLNA). BALB/c mice were dermally exposed to each MWF at concentrations up to 50%. Significant irritation was observed after dermal exposure to all MWFs except CIMTECH 310 and SYNTILO 1023. Of the 9 MWFs, 6 induced greater than a 3-fold increase in lymphocyte proliferation and 7 tested positive in the irritancy assay. TRIM VX yielded the lowest EC3 value (6.9%) with respect to lymphocyte proliferation. Chemical components of TRIM VX identified using HPLC were screened for sensitization potential using structural activity relationship (SAR) modeling and the LLNA. TOPKAT predicted triethanolamine (TEA) as a sensitizer while Derek for Windows predicted only 4-chloro-3-methylphenol (CMP) to be positive for sensitization. When tested in the LLNA only CMP (EC3 = 11.6%) and oleic acid (OA) (EC3 = 29.7%) were identified as sensitizers. Exposure to all tested TRIM VX components resulted in statistically significant irritation. An additive proliferative response was observed when mixtures of the two identified sensitizing TRIM VX components, OA and CMP, were tested in the LLNA. This is one explanation of why the EC3 value of TRIM VX, with respect to lymphocyte proliferation, is lower than those assigned to its sensitizing components. [ABSTRACT FROM AUTHOR]

The utilization of cutting fluids in metalworking industries causes health issues and environmental impacts. Owing to eco-friendly apprehensions and rising regulations over pollution and contamination, the need for a greener approach is increasing to diminish the employment of cutting fluids and dwindle the ecological impact. Therefore, special attention should be focused on clean and sustainable machining processes. Foremost, the optimal setting for multiple response problems in the manufacturing sectors must be acknowledged to reduce energy consumption. Even though machining industries established mist lubrication with vegetable oil and cryogenics as a substitute for mineral oils-based flooding, its meager lubrication and cooling property at elevated speed lead to a hunt for a new hybrid approach that offers adequate cooling/lubrication (C/L). Moreover, as of now, no information concerning the effects of hybrid cooling on milling of Nimonic-80A is existing. In this holistic investigation, machining of Nimonic-80A under hybrid C/L was compared with other cooling strategies (flood, MQL, and cryogenic) to determine the viability of employing cryogenics and hybrid cooling method. Complex Proportional Assessment (COPRAS) technique was applied to select the optimum cutting conditions to get the ideal surface trait. Besides improving the surface quality, the hybrid condition is treated as a trendsetter which is in legitimate agreement with the latest global swing for sustainable means of production. The optimization result indicated that machining at a cutting speed of 60 m/min and a feed rate of 0.04 mm/rev under the hybrid cooling strategy provides the optimal value, that controls the energy requirement. Pugh matrix method has been deployed to establish the sustainability assessment among the distinct cooling conditions. The research verdict illustrates the suitability of the hybrid cooling strategy and explains the process of going green. [ABSTRACT FROM AUTHOR]

This paper presents a method for cost optimum conversion of functional tolerances into machining tolerances transferred to one or more datum reference frames. A new concept - that of the Tolerance Element - is introduced as a machining process-related geometric entity with attributes associated with the accuracy cost. The accuracy-getting capabilities and cost per Tolerance Element are recorded for a particular machine shop through an appropriately designed database feedback form. The Tolerance Elements methodology, once adapted for this machine shop through processing information of the database feedback form, automatically creates application-focused cost-tolerance functions. The latter, in conjunction with the tolerance transfer principle and the machining axes accuracies, are used for the formulation of the problem objective function for cost optimum tolerancing. The system database needs expert updating only when changes occur in the machine shop facilities and/or expertise. The proposed method is demonstrated and discussed by means of an application example. [ABSTRACT FROM AUTHOR]