Machining centres are among the most modern and advanced machines in the metalworking industry. These machines are automated and can carry out multiple machining tasks thanks to computer numerical control, or CNC. Why invest in a machining centre?
Machining centres: the most advanced technology
The main characteristic of a machining centre is that it is automated and can perform different machining processes using computer numerical control (CNC). These machines require minimal human intervention: the operator only has to create the part design, load the workpiece and start the machine. Operations on these machines use rotating cutting tools such as drills.
Today there are different types of machining centre, distinguished by their size, functions and levels of automation. Prices vary according to the model and its features, and represent a significant investment for workshops. The power of these machining centres can reach 75 kW, while spindle speeds range from 4,000 to 8,000 rpm. Depending on their size, some machining centres can take workpieces weighing up to 7,000 kg.
General characteristics of machining centres
Despite differences in size and technical specifications, machining centres share common characteristics. For example, they are reconfigurable. This means that different operations can be performed on the same workpiece in a single machining cycle: the machine spindle head changes tools to, for example, mill and drill the same workpiece in one process. In addition, the workpiece does not need to be repositioned, because the machine repositions it itself.
The many machining operations it can perform are possible thanks to its versatility and flexibility, both of which stem from its high degree of automation. This level of automation also speeds up production processes, as these machines offer high production rates. Thanks to this automation, operators can run several CNC machines at the same time.
The workpieces produced on these machines have excellent surface finishes. These machines are also an excellent choice for series production.
Machining centres support different programming languages (depending on the machine model), such as Java, Python, Perl and so on. They also allow work directly in the CNC alphanumeric language.
Technical requirements of a machining centre
Machining centres must meet certain technical specifications in order to perform operations correctly. Not only must they have the right tools and run the necessary programs, but their construction must also meet a number of requirements. For example, the material used for the machine structure must be highly resistant. The structure and bed are therefore made of cast iron, grey cast iron, forged steel or polymer concrete. Why these materials? Because they have low density, are rigid, have low thermal expansion and high thermal conductivity, and can absorb vibration.
One of the causes of machine tool failure is thermal expansion, as heat sources are both external and internal. Machining centres must have materials, components and mechanisms that keep the temperature at the optimum level for machining, such as a cutting fluid to cool the machining zone.
Computer components
Machining centres are essentially large computers that can turn a part designed on a computer into a real object. As you know, the CNC language works because the part is first designed using software (CAD and CAM). This software is used to design the part and then translate the design into the machine's CNC language.
To carry out these processes, a machining centre needs certain computer components: for example, a central processing unit (CPU), input and output peripherals, data storage units and a PLC interface unit.
The CPU is one of the most important parts of these machines, as it calculates the axis positions, the movements and the machine's operating programs. Information reaches the CPU through input peripherals such as the linear scales, the connection to the computer or the keyboard. Output peripherals, in turn, receive the information supplied by the CPU. The machine's monitor is one of these output peripherals.
Data storage, as you know, holds the information the machine needs. This may be a conventional hard disk or an RS232 connection.
Once the data has been processed in the CPU, the information is transmitted to the various parts of the machine, so that the specified program can be run on the workpiece. This data transfer is handled not by the CPU but by the PLC.