New machining technologies 2021.

Machining has gone through a lot of vicissitudes in recent times, such as the one that is going to drastically decrease or that is going to move to other countries. Currently there are big bets from countries such as the United States, England and Germany, among others, that are committed to recovering manufacturing, which includes machining, encouraging its implementation. On the other hand, within the European Union manufacturing is considered a strategic sector and is being considered in its future plans.

The markets are increasingly demanding in terms of quality, delivery times, costs, increasingly shorter batches, etc. And we find ourselves with less and less loyal customers, which is why it is necessary to adapt to the times through production systems.

Advances are being made in the production means related to machining, mainly machine tools and processes, seeking to respond to the demands of the markets.

Within this last point we are going to carry out a small analysis of what is happening in this field of machining since the fan that opens is very large.

Machining design

Nowadays, the design of the machining process is increasingly important since it is not only necessary to make the part, but it must be done with tighter tolerances, faster, with more complex geometries and right the first time. Many cases using a large number of heterogeneous tools and even contemplating different technologies within the same machine.

To carry out the design of the machining process, there are nowadays programming assistance programs (CAM) that really help to analyze different machining strategies, in most cases from a time point of view but they are already entering in the market simulations of surface states and generated forces, and therefore the chosen strategy can be simulated and in a large number of cases closely approximated reality.

Within machining, it is important to choose or define the strategies that are going to be used in machining since different results can be obtained both in execution times and in quality. Among the strategies, high-performance and high-speed machining can be listed. On the other hand, it is important to know the machinability of the material since it may force us to have to opt for more appropriate strategies for the material. We also have the geometry of the part to be machined in the form of geometric complexity or thin walls, among others, in this aspect it is important to get the most out of the axes that the machine has. Other strategies that exist today are related to the geometric shape in which the machining is carried out, that is,

It has been commented that in many cases different materials processing technologies are included within the same machine and therefore it is not only valid to have a good strategy in one technology but it will be necessary to be able to carry out strategies in different technologies.

Within this multi-technologies section it is important to analyze the collisions that could occur during machining and for this there are solutions both from the simulation aspect and in real time on the machines.

Ensuring accuracy

It has been previously commented that one of the fundamental aspects of the new machining trends is precision and therefore measurement and inspection systems acquire a fundamental position. The tendency is to include them within the production process, as far as possible, and they can be in-process or post-process.

Measurement technology is advancing rapidly as solutions are being developed based on systems that were not previously used for this type of measurement due to their cost or the state of the technology itself. The technologies that are used are very varied and it is necessary to take into account which is the one that best adapts to the measurement that is wanted to be carried out in the most economical way, but complying with the objectives and the reliability of the measurement.

The demands to measure with greater precision together with the appearance of increasingly complex surfaces or that cannot be touched during the process are leading to the development of new non-contact measurement technologies for detection and measurement.

A requirement that is evolving is that of the measurement of residual stresses within the section on the surface integrity of the part and this is an aspect that should be taken into account even in the previous section, referring to machining design, since depending on of the machining process that is applied, residual stresses that are harmful to the part will or will not be generated and it is possible that relaxation operations will have to be included in the processes to which the part is subjected.

The sustainability of the processes

Sustainability is one of the most important aspects of machining trends. Reducing the environmental impact is one of the searches within the developments of machines and processes.

The concept of the life cycle cost of the machine (LCC) with actions to reduce energy consumption or even with eco-design techniques to minimize the environmental impact in the construction of the machine itself are aspects that are being developed. Likewise, there are actions to improve cutting conditions or reduce waste that are advancing through adaptive controls or control of problems in machines that allow parts with zero defects. One aspect that has begun to occur is lean technologies within the development of machines, making them more compact in order to use the minimum available space and within this section, vertical machining could be included.

In the process section, an important factor is the cooling of the machining processes, although there are processes that can be carried out dry, there are a large number of processes that require refrigerant and in some cases a large amount of refrigerant in the form flow or pressure or both. Within this section, the MQL (minimum quantity of lubricant) technology was developed years ago, but it is still not fully exploited. On the other hand, cryogenization has begun to be used to support machining in milling, drilling and turning operations in order to increase the life of the tool.

If we analyze grinding, which is one of the processes that uses the most refrigerant, we find several trends. The first one is to use the heat generated to temper the piece, which is called Green Hardening. The second is the optimization of the nozzles that project the coolant into the wheel-piece contact, seeking greater effectiveness and increasing the life of the wheel as well as effecting changes in the process parameters to increase productivity. The third is the use of the cryogenization concept, freezing the coolant on the surface of the grinding wheel so that due to the heat of the grinding wheel contact it defrosts, this process allows drastically reducing the consumption of refrigerant and is considered as the MQL of the grinding.

Other aspects related to sustainability can be energy recovery in the machine when braking is made, leaving the machine in standby, either the whole machine or components that are not in use, having friendly concepts for its use, friendly concept. Improving ergonomic and safety aspects of machines. There are even companies that the aesthetic concept is gaining importance with studies that say it improves productivity.

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