A device (100) for mixing a coolant and a lubricant comprises an inlet port (2) for receiving the coolant, a pressure amplifier (10) coupled to the inlet port (2) and configured to increase the pressure of the lubricant by means of the pressure of the coolant, and a mixing unit (16) coupled to the inlet port (2) and the pressure amplifier (10) and configured to mix the coolant and the lubricant provided by the pressure amplifier (10).
F.32 International patent
COBISS.SI-ID: 16671771Modern trends in machining include sustainable manufacturing with the focus on reducing the consumption of conventional cutting fluids. These alternative cooling-lubrication principles include Minimum Quantity Lubrication (MQL), cryogenic machining and dry machining. In the absence of abundant quantities of cutting fluid, adequate lubrication is needed, especially when difficult-to-machine materials are considered. High friction during machining leads to heat generation, which adversely affects the tool life, workpiece surface quality and energy consumption. Consequently, lower cutting speeds are employed. Solid lubricants such as molybdenum disulphide or graphite provide excellent lubrication in severe conditions, where contact pressures and temperatures exceed the operational limits for conventional oils. These solid lubricants can be added to cutting fluids, e.g. in oil for MQL, to enhance their thermal and tribological properties. Their unique structure can provide lower friction coefficient, thus reducing the generated heat and prolonging the tool life. Presented in the paper is a performance evaluation of solid lubricant (MoS2, average particle size 2 µm) from the tribological viewpoint. An open tribometer has been developed to estimate the friction coefficient between uncoated carbide tool and AISI 1045 workpiece at machining-like conditions which include high contact pressures and sliding speeds. To show the potential of solid lubricant, a comparison has been made with dry, flooding, MQL, cryogenic and combination of MQL and cryogenic conditions. Molybdenum disulphide showed excellent lubrication performance under all considered sliding speeds, outperforming the conventional lubricants, opening the possibility of further research in the area of solid lubricant assisted machining.
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 16249115A sustainable approach to increase the productivity in milling of difficult-to-cut materials is the use of internal cryogenic cooling combined with minimum quantity lubrication (MQL). There are various systems available on the market to control the flow of the cryogenic and the MQL medium. These systems are usually based on a delivery of the media through two separate channels. Moreover, a single channel system, which uses the solubility of oil in supercritical CO2 is state of the art. Compared to a two-channel system the geometry of the cooling lubrication channels is simplified, the tools are more stable and easier to manufacture. Furthermore, there is no negative interaction between the CO2 and MQL jets. Instead of supercritical CO2 (SCCO2), liquid CO2 (LCO2) is easier to handle and widely available. Therefore, this paper presents fundamental investigations of the solubility of liquid oil in LCO2. In addition, an innovative single channel system was designed, implemented and tested in milling process of Ti6Al4V.
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 16646171The paper presents how the phase of nitrogen influences the surface heat transfer coefficient. The determination of the phase influence has been defined by resolving the inverse problem with conducted experiments and verified by the numerical simulation. The experimental part includes the temperature measurements in the material at the time when the nozzle moved across the plate. The results have shown that the surface heat transfer coefficient reaches maximum value of 75000 W/(m2K), when nitrogen is in liquid phase. From the FEM results, it can be detected that value for the surface heat transfer coefficient decreases with increasing temperature of boundary layer which has been created by liquefied nitrogen on the Inconel 718 workpiece.
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 15515931Modern trends in machining lean towards the use of dry machining processes, or in alternative cooling-lubrication systems such as Minimum Quantity Lubrication (MQL), cryogenic or high pressure systems. High heat generation is critical for the quality of workpiece surface, tool life and energy consumption. Lubrication in the cutting zone is an effective way to reduce the generated friction and consequently heat. Solid lubricants have proven to be an effective way in reducing the friction in mechanical contacts. The most acclaimed substances include recently synthesized graphene and molybdenum disulphide. Also, their application in the machining processes can provide the reduction of the friction in the cutting zone, which consequently results in the prolonged tool life, increased surface quality, higher productivity and economically viable process. Different cooling lubrication techniques were tested by evaluating their influence on the coefficient of friction by the use of special tribometer, designed for high contact pressures. This work thus shows the potential of solid lubricants for improving machining performance.
F.18 Transfer of new know-how to direct users (seminars, fora, conferences)
COBISS.SI-ID: 15603483