Tomas Beno

Impact of energy efficiency on computernumerically controlled machining

Abstract Increasing environmental demands from governmental bodies and customers stress the importance of companies improving their environmental performance. The research presented here shows that productivity and cost efficiency improvements can be achieved alongside energy savings in a computer numerically controlled machining environment. This improves the profitability of the companies, but also leads them towards more sustainable and environmentally aware manufacturing; the relationship between machining parameters, machining costs, and energy consumption is evaluated. From this perspective, it is important that production planners etc. understand the methodological possibilities for improvements in cost and energy efficiency. The current research is based on a machining cost model and experiments where energy consumption and tool wear were monitored.

Machining aerospace materials with room-temperature and cooled minimal-quantity cutting fluids

The impact on the cutting forces and tool wear in the turning of the four most common aero-engine alloys (Inconel 718, Waspaloy, martensitic stainless steel, and titanium alloys) with minimal-quantity cooling lubrication fluids both at room temperature and when cooled have been investigated for different cutting conditions. Parameters such as the fluid-type and cutting insert materials used were varied, as were the cutting parameters. Methods of statistical experimental design were used in order to extract, in the smallest number of experimental runs, the maximum amount of information from the collected data in the presence of noise. In this work, no evidence is found that lubrication plays a significant role during the turning of high-temperature alloys. When using room-temperature liquids, the cutting forces show in most cases either no significant changes or an increase. For the cooled cases, both significantly increasing forces and significantly decreasing forces can be observed. The most favourable industrial result is the reduction in the tool wear that can be seen for the machining of titanium alloys.

Energy and Cost Efficiency in CNC Machining from a Process Planning Perspective

The role of process planning as an enabler for cost efficient and environmentally benign CNC machining is investigated in the paper. Specific energy is used as the principal indicator of energy eff ...

Investigation of Minimal Quantity Lubrication in Turning of Waspalloy

In order to achieve a more productive and environmentally friendly manufacturing of aerospace propulsion components, minimal quantity lubrication (MQL) can potentially replace the traditionally used flood cooling in different machining operations. These components are manufactured of difficult to machine alloys, which show great hardness even at elevated temperatures. Waspaloy is one of the more demanding super alloys to machine and serve as reference material in this investigation. In this paper, a turning operation is used to investigate the influence of MQL parameters such as oil type together with cutting data on cutting forces and tool wear. As a reference flood and air cooling was used. Two different type of oils were investigated, ester vs. fatty alcohol. The aerosol was directed towards the tool by two different nozzles. Responses that were measured include particle size, aerosol generation capability, cutting forces and tool wear. The experiments were conducted as a D-optimal design of experiments and evaluated by a regression analysis. No evidence of any lubrication effect can be seen. The most plausible explanation of the effects seen is the effects of cooling and heat transfer.

Next Generation Insert for Forced Coolant Application in Machining of Inconel 718

Machining technology has undergone an extensive evolution throughout the last decades in its capability to machine hard-to-cut material. This paper will discuss about the next generation insert with cooling feature coupled with forced coolant in machining Inconel 718. The geometry of the insert was changed in a way which has enlarged the surface area approximately 12% compared to regular insert named as nusselt insert. The idea applied in “nusselt insert” was the relation of increase in surface area to heat dissipation. Forced coolant application has become a way to improve existing metal cutting concepts and improve their current material removal rates without any need for a reengineered machining process.Experiments conducted on the inserts is that the first experiment of its kind in machining technology together with forced coolant and tested in four different inserts. The primary focus of the work was the investigation of the relation between the heat dissipation with an increase in surface area/mass ratio in the cutting interface based on its influence on tool wear. The experimental results showed the nusselt insert have better ability for heat dissipation which has led to significant reduce in tool wear and successfully facing Inconel 718 at vc 105 m/min, f 0.3 mm/rev and ap 1 mm where the regular insert had a catastrophic failure at vc 90 m/min, f 0.1 mm/rev and ap 1 mm. Nusselt insert has shown to increase MRR significantly compared to regular insert.

Cutter Exit Effects during Milling of Thin-Walled Inconel 718

During milling of thin-walled components, chatter vibrations give rise to process issues. These include dimensional inaccuracy, damaged and scrap parts, and damaged cutting tools. This, in turn, leads to loss of production time with increasing cost as a consequence. This paper identifies the force profile during a single cut milling process. It focuses on the exit and post-exit behavior of the cut and discusses the process dynamics. The force profiles of various tool-to-workpiece positions are analyzed as regards the exit and post exit phases. A standard on-the-market cutter and a specially designed zero rake cutter are used in the investigation. Finally, a time-domain simulation of the force is performed and compared to the experimental results. The study concludes that a small change in exit angle may result in a considerable improvement in cutting behavior. In addition, the tool position should be chosen so that the cutter exits in the least flexible direction possible for the workpiece.

Green Key Performance Indicator Based on Embedded Lifecycle Energy for Selection of Cutting Tools

Many companies face increasing demands from markets to have environmentally friendly manufacturing processes. This paper proposes a Green Key Performance Indicator for selection of cutting tools, based on embedded lifecycle energy of the insert. This facilitates decision making to achieve green machining. Two insert materials were investigated; one solid carbide and one ceramic insert. The main work piece material was gray cast iron. The results show that the embedded lifecycle energy of a ceramic insert is considerably higher than for cemented carbide but, due to higher material removal capacity, the ceramic insert has a better Green Performance Indicator.

A survey of metal working companies' readiness for process planning performance measurements

The paper presents an investigation regarding the potential and the readiness for implementing performance indicators and performance measurement systems of the process planning work for metal working companies. The paper is based on a questionnaire survey distributed to process planners in the Swedish metal working industry. The main outcome of the investigation is a foundation for understanding the implementation of performance measures of the process planning work for CNC machining. The survey revealed a few strengths and short comings in the studied companies.

Influence of radial depth of cut on entry conditions and dynamics in face milling application

The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavorable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. Under some circumstances the radial depth of cut in combination with milling cutter geometry might give unfavorable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon is originated from the geometrical features that affect the rise time of the cutting edge engagement into workpiece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult-to-cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the workpiece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behavior is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using the root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.

Characterization of tool wear when machining alloy 718 with high-pressure cooling using conventional and surface-modified WC–Co tools

Coolant supplied by high pressure into the cutting zone has shown the lower thermal loads on the tool when machining difficult-to-cut materials as the Alloy 718. In this study, we investigate how the combination of high-pressure cooling and tool–surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant–tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by ~ 12%. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45% for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivity of metal cutting processes.