What is a machine tool

Machine tools

Modern machine tools are primarily characterized by the production or processing of workpieces with tools. As working machines, they - and not humans - determine the mutual guidance of workpiece and tool in operation. Together with measuring and testing equipment, devices and simple tools, machine tools are part of the operating equipment and can be subdivided in more detail on the basis of their diversity in different ways.

Due to the rapidly advancing technical development, machine tools are increasingly defined as mechanized and possibly automated production facilities. The latter addition is representative of the technical progress and current endeavors of the industry: Both the automation and the networking of machines with intelligent systems have a major influence on the nature and role of machine tools within the industrial sector.

Construction of machine tools using assemblies

Although the variety of machine tools - as well as the number of their fields of application - is enormous, they usually have a similar, almost common composition. This typically consists of modular assemblies, which make the respective machine fully operational only in combination. In the style of the building block principle, the modular design not only allows easy commissioning, but also offers the possibility of meeting specific requirements from application to application. In addition, components of the system can be replaced at a later point in time.

The machine frame serves as the basic assembly and basis of every machine tool. This gives the entire machine its physical appearance, carries the other components and connects them to one another. The frame of a machine tool is of great relevance, especially in the case of large, complex devices that are subject to high loads. In contrast to small machines, in which a modified table often functions as a frame, machine frames for larger devices must have resistance to elastic deformation. When choosing the material for the frame, properties such as density, damping and thermal conductivity come to the fore. Some machine tools also require a cast foundation to ensure high rigidity.

The assembly of guides and bearings is also decisive for the continued functionality of machine tools. This specifies the axes on which moving machine components can and should move. Because guides and bearings are in direct contact with other components of the system, they are subject to wear, which can be reduced, for example, by using ball bearings.

Control and drive - pioneers of automation

 As the primary drive unit, the motor and gear unit are responsible for the leading working movement of the machine tool. There are also various auxiliary drives, including so-called feed drives for positioning the tool. However, the various drive elements not only set a machine tool in motion - they also represent an important factor for the working accuracy and the quality of the processed workpieces. Harmonic DriveĀ® hollow shaft drives from the FHA, CHA and CanisDriveĀ® series have corresponding properties. Thanks to a reinforced output bearing with the highest level of tilting rigidity and precision, the said drives can take high loads quickly and easily; they also guarantee a long service life and, if necessary, short swivel times.

The control unit is basically used to automate a machine and takes on various tasks that were previously carried out manually or with the help of mechanics. It controls and monitors production steps, saves machine and tool-related data and saves production programming. Modern machine tools rely on electronic systems, for example semiconductor components and relays, but above all on numerical controls. The latter offer much greater flexibility than many other sequence controls.

Further assemblies of modern machine tools are tool storage and changers, workpiece changers, tool holders and supply and disposal devices. There are also safety devices and measuring systems (e.g. for determining the position of the tool).

Typical assemblies of a machine tool at a glance:

  • Machine frame (optionally with foundation)
  • Guides and bearings
  • Drives (main drive and auxiliary / feed drives)
  • Control (electronic, numeric)
  • Tool storage and changer
  • Workpiece changer and tool holders
  • Safety, supply and disposal facilities
  • Measuring systems (for example for position determination)

Classification of machine tools according to manufacturing process

Whether the number of axes, kinematics, accuracy or the degree of automation - machine tools offer numerous classification options. One of the most prominent and most frequently used classifications is the classification based on classic manufacturing processes. Lathes and milling machines as well as drilling machines, sawing machines, grinding machines and similar devices are assigned to the cutting class, while bending, rolling machines and presses belong to the forming machine tools. Guillotine shears and punching machines are now among the dividing machines. The class of abrasive machines includes laser processing and water jet cutting machines. Machines that accomplish tasks such as welding, soldering and gluing are part of the joining class.

Machine tools over time

The mass production of durable goods and consumer goods in the 21st century is largely based on the continuous development of machine tools. Today, powerful, almost completely automated machines are part of the basic equipment of modern manufacturing companies and manufacturers in the industrial sector. However, the history of machine tools did not just begin in the last few decades - forerunners of today's machine tools emerged many centuries, even millennia ago. The invention of what was possibly the first machine tool, a primitive drilling device, dates back around 6000 years. Even if this and following devices, including lathes and grinding machines, cannot be compared with today's models, they meet some criteria of current definitions of machine tools.

In the course of the industrial revolution and due to social change, the need for ever more powerful and advanced machine tools increased. Manual intervention by human hands decreased continuously, as new innovations made it possible to achieve significantly higher economic efficiency and production volumes. The rapidly growing demand not only made the machines very popular, but also ceaselessly promoted their technical progress. It was only through the development of special lathes and drilling machines in the 18th and 19th centuries, for example, that metal was able to establish itself as a common material. In the 20th century, Computerized Numerical Control, or CNC for short, was the next big step in development. This is a computer-aided numerical control of machine tools, which is individually adapted to the respective application and usually has its own operating system and user interface.

Machine tools and 3D printing in comparison

In the course of time, in addition to classic machine tools, another very rapidly growing technology has been able to establish itself - additive manufacturing. This became known in particular through so-called 3D printing, which was not only withheld from ultra-modern production halls, but can also be used in your own four walls with the appropriate device. The reasons for the rapid rise of 3D printing and additive manufacturing in general are many; technically decisive, however, is a very specific difference. Objects are manufactured subtractively by classic machine tools, while processes such as 3D printing are additive. The difference quickly becomes clear when using pictorial language: machine tools separate material from a block of material like a sculptor knocks pieces of stone or wood to form the blank. In contrast, with 3D printing, a material is put together layer by layer until the desired object is created.

The opposing approach of classic machine tools and additive manufacturing methods determines the properties of both processes. Machine tools are therefore assigned an extremely high level of accuracy, while 3D printing is given freedom of form, speed and the opportunity to save both costs and weight, which is particularly important in areas of application such as aerospace. Acquisition and operating costs, material compatibility, size restrictions, and ease of use also vary depending on the process. However, the latter is primarily attributed to additive manufacturing processes as an advantage.