Introduction to Nano machining

Nano machining is expected to be the flag bearer of the next technological revolution. Nano machining essentially involves exploiting materials and their properties at the nanometer scale.

One of the most important challenges to the widespread application of nanotechnology in everyday life products is related to the manufacturing technology and costs associated with these methods. The challenge is not only to manufacture parts with nanometer-scale features, but also to integrate them with parts and macroscopic devices with micrometer-scale features.

1.What is nano machining?

There are two definitions of nano machining. The first definition is that nano machining refers to the manufacture of parts with nanometer-scale overall dimensions. The second definition is that it is a machining process that must maintain an accuracy of 100 nanometers or less regardless of the size of the overall product.

Nano machining can be roughly divided into four types:

1) Abrasive nano machining

In abrasive machining, abrasive particles are used to remove small amounts of material from the surface of the part. The size of the abrasive particles used determines the scale of the features to be produced. Honing, polishing, and grinding processes all fall into this category.

2) Non-mechanical nano machining

These methods include micro-electrodischarge machines (EDM) and focused ion beam machining, among others.

3) Lithographic methods of nanofabrication

By using masks, two-dimensional parts and features can be produced with nanometer-scale precision. These methods are limited to creating two-dimensional parts. Techniques include X-ray lithography, electron beam lithography, etc.

4) Mechanical nanomachining

This method uses tools in traditional mechanical machining to remove material at the scale of tens of nanometers. The tool path and surface determine the shape and quality of the workpiece to be manufactured. Processes include nanogrinding, micromilling, and diamond turning.

Mechanical nano machining is more popular than other machining methods because it is able to generate complex three-dimensional geometric features at different length scales. For example, mechanical nano machining can be used to manufacture micro molds with complex geometric and shape features at the nanometer scale.

Important physical parameters of mechanical nano machining include cutting force, cutting energy, cutting temperature, chip formation, and surface generation. These parameters provide a means to understand the physical process of machining.

Molecular dynamics simulation (MDS) is used to determine these parameters theoretically. Critical cutting edge radius, minimum undeformed chip thickness, and the properties of the workpiece material also play an important role in understanding the machining process.

2.Factors to consider for nano machining

In order to successfully implement nano machining, the following factors must be considered while taking into account mass limitations.

1) Ultra-precision machine tools

To manufacture precision parts at the nanoscale, machines consisting of ultra-precision machine tools must be used. As a whole, these ultra-precision machine tools must have certain characteristics.

These characteristics include high mechanical and thermal stability of the parts. The natural frequency and ring stiffness values ​​of the structure must be high. As a whole, these tools must exhibit low vibration. The control and movement of the axes must be extremely precise.

Four major systems are required to form an ultra-precision machine tool (drive and spindle, mechanical structure, measurement system, control system).

2) Cutting tools

The most commonly used cutting tool in nano machining is the diamond tip. Diamond is preferred over other materials due to its characteristics. The advantages of using diamond tip tools include: better thermal management due to the high thermal conductivity of diamond.

Due to the crystal structure of diamond, extremely sharp cutting edges can be produced. Diamond tools also have strong wear resistance. During machining, diamond tools deform less due to their high shear and elastic modulus values. Diamond also has a high hardness.

Cutting tools made of diamond also have some disadvantages. Diamond lacks toughness and has an affinity for ferrous metals. Grinding wheels used in nanomachining are usually made of diamond combined with metal.

3) Nanometrology

It is extremely important to master methods and techniques that can help us determine the quality of parts after nanomachining. High-precision measurement of size, shape, texture, and surface integrity is essential for effective quality control of nano parts.

Laser interferometers are widely used for position measurement with nanometer-level precision. Scanning probe microscopes and optical profilers are widely used for surface texture measurement.

Measuring shape (such as the curvature of a circular surface) becomes particularly important, especially for optical-related applications, where deviations from a perfect shape may cause the part to fail during functional testing. Interferometric techniques (i.e., phase stepping) are used to determine the consistency of complex shapes with the original design.

3.Variables in nano machining processes

The intended function that the product must perform determines the design and control process, which in turn determines the machining variables. Factors such as surface roughness, wear resistance, friction, lubrication, etc. play a decisive role in the selection of machining methods and parameters.

4.Applications of Nano machining

Nanoelectromechanical systems (NEMS) are an advanced form of microelectromechanical systems (MEMS). These systems integrate electrical (e.g., transistors) and mechanical (e.g., pumps and actuators) systems at the nanoscale.

NEMS are mainly used in accelerometers and detection of chemicals in the air. Giant magnetoresistance (GMR) structures used in computer hard disk read heads are one of the most well-known applications of nanoscale devices.

Other applications of nano machining include the fabrication of astronomical mirrors and other optical instruments for optical instruments.

Nano machining is also used to process nanoscale channels for nanofluidic devices. Another potential application area of ​​nano machining includes micro drug delivery systems.

5.Conclusion

Devices with features of a few nanometers in length are gaining increasing attention from scientists and engineers due to their potential use in a variety of fields such as the food industry, biomedical devices, electronics, mechanics, etc.

One of the major obstacles faced by designers and developers of such devices is their manufacturability. The body of knowledge about nano machining is helping scientists and engineers make progress in manufacturing such devices.

Molecular dynamics simulations (MDS) provide necessary information about important nano machining factors such as cutting forces, cutting temperature, cutting energy, chip thickness, and many other relevant parameters.

To achieve nanoscale precision, the selection of ultra-precision machine tools and ultra-precision cutting tools is very important. Being able to measure and inspect the nanoscale features produced helps ensure quality parts that pass functional testing.