A machining center, is a great machine automation that is capable of performing various machining operations within a facility under CNC (Computerized Numerical Control) with minimal human intervention. The most common operations in which this machine is used are those that use cutting tools rotary as drills and cutters. Compared to this system machining With the more traditional systems, the production speed stands out as an advantage and the necessary investment as a disadvantage.
Characteristics of a machining center
These machining centers They have the following characteristics.
- The versatility and flexibility that due to the high degree of automation, makes them capable of executing different machining operations on a single piece.
- Provides a good surface finish, which makes them suitable for giving the final shape to the pieces that are manufactured.
- These machines are reconfigurable, as they can quickly change settings to perform various machining tasks on a part.
- Uniformity in production, a necessary condition for mass production.
- High production speed, due to the fact that they carry out a large number of operations automatically on the workpiece.
Some of the virtues that demonstrate the flexibility and reconfigurability mentioned are the automatic change of tools, the use of conveyor pallets and the automatic positioning of the workpiece.
To compare a little the benefits of the machining centers conventional and machines modern with CNC (Computerized Numerical Control), we will use this table.
Machining center structure
Some characteristics to take into account in the design of the structure of a machining center are the materials used, the rigidity, the thermal expansion and the vibration damping capacity.
Always keep in mind that the materials to be used have some requirements.
- Stiffness, so that deformations can be minimized when loaded and vibrations minimized.
- Low thermal expansion.
- Low density, so that it is possible to minimize inertial forces.
- High thermal conductivity, which is desirable in some parts, to make it easier to quickly remove the heat that is generated by cutting.
- Ability to absorb vibrations.
- Low cost.
The materials that make up the frame of a machining center They are gray or cast iron, polymer concrete, ceramic, and composite materials.
- The cast iron. It has a low cost level and a very good vibration absorption, but the parts turn out to be very heavy in relation to its mechanical abilities. This is the first material used for machine tools.
- polymer concrete. This material is a mixture of crushed concrete and plastic, which can be easily melted, so that it can take different forms. It has high vibration capacity but very low stiffness and also low thermal conductivity.
- Ceramics. These are used in advanced machines, their great advantages are rigidity, specific strength, corrosion resistance, good surface finish and great thermal stability. A good example of application are the screws and bearings that are made with silicon nitride, which also has good friction and wear.
- Composite materials. These can be formed by a great variety and combination of matrices, they also have good mechanical properties. Its use is very restricted due to the high cost with which it is characterized despite having great precision and speed.
Types of machining center
There is a wide variety of machining centers characterized by their sizes, types, functionalities and degrees of automation.
The nominal powers reach 75KW and the spindle speeds of the most common and used machines are those that have limits of 4000 to 8000 RPM, although for some more special applications, they can reach 75000 RPM.
Currently, many machines are built in a modular way, so that they can install and modify various accessories and peripheral equipment, as necessary in the changes to the products to be manufactured.
Among the types of machining centers we can differentiate those of vertical spindles and those of horizontal spindles.
- The vertical spindle machining centers they are more suitable for performing operations on flat surfaces with deep cavities, an example is the manufacture of dies, molds or dies. Since in vertical machining the thrusts are directed downwards, these machines have high rigidity and produce parts with good dimensional accuracy. In general, these machines are much less expensive than those with a horizontal spindle.
- The horizontal spindle machining centers They are recommended for use in large and tall pieces, which require machining in several parts of their surfaces. In some cases, the part being machined may be tilted about different axes to occupy different angular positions. The turning center, is a category of horizontal spindle machine. These computer controlled lathes often have more than just one horizontal spindle and turrets equipped with a wide variety of cutting tools.
Machining Center Video