Recent Advances in Mechanical Micromachining - Essay Example

Micromechanical processing Micromachining just like conventional machining refers to the removal of materials from a work piece the only differences being that in micromachining in the pieces are too small and require special handling, special cutting tools with edges that may range from nanometers to micrometers and the chip formation and removal are quite different. This problem of machining the small pieces calls of special material removal methods such as the geometry defined cutting edges of the purpose of creation of precise the dimensional work pieces with dimensions ranging from a few tens of nanometers to a few millimeters (Dornfeld & Takeuchi, 2006).

There are much considerations to be taken when machining small pieces due to the imperfections per unit volume that are due to the size effect of the work piece and the strain effect that is caused by the size effect during machining of the small pieces of work pieces (Dornfeld & Takeuchi, 2006). An example is energy dissipation that has been neglected or along time in micro machining that resulted to significant subsurface plastic flow to the shear zone under the machined surface.2. One of the micro geometries created through micromachining is the fabrication of multi level mold inserts for micro molding of a microwave system.

This involved combination of micromachining with deep etches X-ray lithography that resulted to creation of micro molds with features in the range of 60µm in height and 50µm wide. This portrayed the possibility of stacking several mold so high aspect ratio parts (Dornfeld & Takeuchi, 2006).3. Micro tooling refers to using the correct tools in micromachining. The cutting edge of radius of a crystal sharpened diamond for example is on the order of 10nm and the depth of such a tool is in the submicron range.

Micro tools are fabricated by ion beam process. An example is the gallium focused ion beam that generates a number of cutting edges and tool end clearance and machined surface with the same as eh diameter of the tool. The use of wire electric discharge grinding (WEDG) (Dornfeld & Takeuchi, 2006) is also common in tool fabrication. WEDG involves a sacrificial wire that replaces the turning tool in conventional turning. Material is then eroded from the rotating tool with electrical discharges. The sacrificial wire in this case is fed around a reel and takes up system that would prevent discharges from worn out regions and this increases the accuracy of the tool shape (Dornfeld & Takeuchi, 2006).

Micro tools are usually made from tungsten wire due to its high boiling point and melting point, high thermal conductivity and thermal diffusivity. Diamond is also a good cutting tool due to its hardness but tungsten is mostly preferred as diamond has a high affinity to iron.4. Cutting fluid in micromachining is used to remove burs and to control the cutting temperature between the cutting tool and the work piece. However, the use of cutting fluid has been proved to result to less accurate dimensions and the removal of the excess cutting fluid at the end is also major problem (Dornfeld & Takeuchi, 2006) minimum quantity lubrication (MQL) is therefore preferred in this case.5. Metrology is the science thought which precession and accuracy in machining process are maintained and ensured.

Since micromachining is preferred for highly accurate and precise work pieces, most of which are much smaller compared to the conventional machining work piece, metrology ensures that the dimensional accuracy and the exact size of the workspace has been achieved. The under formed chip in micromachining is of a few microns thick and overall machining in the chip formation and the material properties as well as the cutting tool edges are of much importance at this rate. Metrology in this case ensures that all aspects involved in micromachining process are as precise as possible to result to the required finish of the work piece.

ReferenceDornfeld, D., Min S., & Takeuchi Y., (2006) Recent Advances in Mechanical Micromachining. Annals of the CIRP Vol. 55(2).