Micro Machining Report

The cooling application in machining processes plays a very important role as many operations cannot be carried out efficiently without cooling (Yildiz, Y. 2008). A part from that there is a number of interesting research results have been obtained on problems which are relevant to MQL. A quick review of the relevant experiments and process provides a picture of the current state of this thesis.

2.1 Micro Machining
Micro milling, one of the mechanical micromachining methods, is a process that utilizes end mills that typically vary in diameter from 100 to 500 µm and have edge radii that vary from 1 to 10 µm (Dhanorker, A. 2008). In addition, the micro milling process has several important features that differentiate it from the macro end

The chip is not continuously made in micro milling when tool and workpiece is engaged as different to conventional milling (Dhanorker, A. 2008). Chip formation and desired surface roughness also highly affected by the tool deflection in the micro milling compared to conventional milling. As the chip load is small compared to the cutting edge radius, the size effect and working forces become important on surface roughness in micro milling. Micro milling may result in surface generation with burrs and increased roughness due to the ploughing dominated cutting and side flow of the deformed material when the cutting edge becomes worn and blunter. There are several phenomena in micro milling that prevent the results of conventional milling from being applied to it directly. First, it cannot be assumed that the micro structure of the workpiece material is homogeneous. As tool size becomes smaller, its effect becomes more important. In this work it was used an Ø 0.8 mm tool, and for simplicity this effect was not assumed. Second, the effect of the cutting edge radius is not negligible: it affects the chip forming mechanism. Minimum chip thickness is a function of this parameter, and determines the transition between two cutting conditions; where chips are produced and where ploughing takes place (Dhanorker, A. 2008). Figure 2.1 shows the inputs and influences in micro

Spraying the lubricant can cause the smell to be intensified.

2.6.3 Spray ability
The lubricant should spray easily and, especially with 1-channel systems, be able to produce a stabile aerosol (oil-air mixture).

2.6.4 Additives
The additives should be adjusted to the processing requirements, particularly when processing non-ferrous metals and difficult-to-cut steels.

2.6.5 Residues on machine parts
Despite minimum spray amounts and the use of extraction devices, lubricants may leave residues on work pieces and machine parts. The lubricant should not resinate and should be easy to clean off if necessary.
2.6.6 Viscosity range
Practical experience shows that the best results with lubricants (ester or fatty alcohol) are achieved at a viscosity range of 15 to 50 mm2/s and in some cases up to 100 mm2/s at 40 °C. Upper viscosity limits should be discussed with the MQL system manufacturer (check device suitability for spray ability). In general the MQL system and lubricant should be compatible with each other.

2.6.7 Lubricant change
Before a new lubricant is used, the system should be completely drained and flushed. The flushing process should be performed with the new