Environmental Impact Reduction for a Turning Process: Comparative Analysis of Lubrication and Cutting Inserts Substitution Strategies

AbstractMachine tools are responsible for a relevant share of environmental impact related to production processes. This is due to their widespread use, the huge energy requirements during operations and the disposable materials involved in the process like scraps, cutting inserts and exhausted oil. This study presents a holistic analysis of the main contributions that are responsible for the environmental impact of the process and the use of the analysis's results to optimize the process setup for a specific case. The factors included in the analysis are: cutting parameters, lubrication strategy and cutting inserts substitution. Regarding the cutting parameters choice, the analysis of the tests carried out highlighted that the best solution is to use the most demanding process parameters in terms of material removal rate, using the tool strength as a constraint. The comparison of alternative lubrication strategies shows the advantage of using dry machining, to be replaced with MQL only when hard-to-cut materials must be machined. Finally, the approach developed to assess the environmental footprint associated to the cutting inserts allowed to define a new substitution rule. The obtained solution is consistent with the usual industrial practice to change the tool when the geometrical tolerances could not be meet anymore, this result is due mainly to the high environmental impact of the production phase of the insert

Investigation on Optimal Mobility System using Axiomatic Design and Scoring Matrix: the “Drive Ability” Experiment

AbstractThe increase in the global population and the improvement of the life style of many poorer countries are leading to a relevant growth for mobility. Such increase in circulating vehicles would have a negative impact on environment pollution. Given this picture, the traditional internal combustion engine vehicles could not be the best solution for the future personal mobility. This problem is really critical especially for high population density cities, such as Firenze (Italy), where the large number of circulating vehicles must use a very old infrastructure that is constrained by all the historical sites widespread in the city, that are also very sensitive to air pollution. However, choosing between the possible mobility solutions could not be an easy task, also if using a structured approach. The challenge is, in fact, to assess a large number of variables for different solutions, process that could lead to a situation where all scenarios show pros and cons, and so all matrices will be decoupled and will not be possible to define which solution is the best. The aim of this paper is to define a new approach, based on a Scoring Matrix and on the Axiomatic Design, which overcomes this issue by using a multi-criteria evaluating strategy. This new approach has been tested on the city of Firenze (Italy) where the optimal mobility paradigm has been assessed from the sustainability point of view. As a result, the wireless charging system has been identified as the most suitable for the city and citizen needs. In addition, Axiomatic Design has been used to define how to overcame the technological barriers for its introduction: wireless charging introduction, in fact, could experience a stop due to the efficiency loss in case of misalignment. In this paper, the scenarios are introduced using the Axiomatic Design decomposition tree and the solution has been tested by using the information axiom

Effects of cutting conditions on forces and force coefficients in plunge milling operations

The modeling of milling forces is a crucial issue to understand milling processes. In the literature, many force models and experiments to identify force coefficients are found. The objective of this article is to develop a new approach, based on the traditional average force method, able to measure and compute the cutting coefficients for end mills used in plunging operations. This model has been used to evaluate the effect of the radial engagement on the cutting coefficients themselves, proposing a new strategy to update these values for different cutting parameters. This dependency of the cutting coefficient is particularly important for the determination of the stability lobe diagrams, used to predict the chatter conditions. In this article, the method to assess the cutting coefficients, the results of the experimental tests, and the effect of condition-dependent cutting coefficients on process stability are presented

Design of An Active Workpiece Holder

AbstractMilling is one of the most used machining processes thanks to its high flexibility and high achievable quality. The performance of milling machines is constantly increasing, improving the convenience and increasing the competitiveness of this operation. However, the trend of performance improvement has found a technological limit: self-excited vibrations due to the dynamics of the system machine-workpiece-tooling (i.e. chatter). Chatter is the most dangerous dynamic phenomena that could happen during milling; due to its regenerative nature, it could lead the machine and the tooling system to a heavy fault or to the disruption of the workpiece. This paper develops an active workpiece holder that avoids chatter vibrations by a smart actuation of the workpiece. The design of the workpiece holder is a difficult task due to strict product requirements and the need to create a decoupled structure. The decoupling of the structure is a fundamental requirement of the product because this affects the controllability of the system. Axiomatic Design Theory is used to support the definition of the product requirements and the product architecture. After the definition of the optimal structure of the workpiece, the design features are integrated in order to obtain a functional decoupled structure