Machining is the most important process for manufacturing parts in the metalworking industry. It makes it possible to create parts that are supplied to other industries (manufacturing, automotive, aerospace and so on) to make products. The machining area within a workshop, however, plays an essential role in ensuring this work is carried out successfully.
What is machining?
Machining covers the work carried out in the metalworking industry and consists of transforming raw material into parts and components that are supplied to other industries. Today there are three different types of machining: with chip removal, without chip removal and by abrasion.
Machining with chip removal
The first group includes the work carried out on machine tools such as lathes and milling machines. These machines use cutting tools (drills, milling cutters, lathe tools and so on) which, as they approach the surface of the workpiece, remove excess material to achieve the desired design and shape. The material removed comes off as small flakes of different sizes and thicknesses, known as swarf.
Chip-removal machining processes can in turn be classified as:
- Roughing: a large amount of material is removed, but with low precision.
- Finishing: little material is removed, but with high precision. This type of machining is used as the final process to give the part a better surface finish.
Without chip removal
Unlike the machining described above, machining without chip removal does not use cutting tools that produce material waste. This type of work can be done on machines such as presses, which carry out only forming and deformation of metal sheets. In other words, the part is not cut, simply transformed. This group also includes highly advanced techniques such as laser cutting and waterjet cutting, in which the part is cut but no material is wasted. Forging and welding are also forms of machining without chip removal.
Machining by abrasion
Finally, abrasive machining is carried out on grinding machines. These machines work with a tool called a grinding wheel; as the name suggests, the abrasive materials of the wheel wear away the surface of the workpiece without producing chips. This type of machining complements other processes such as turning.
Optimising the workshop's machining area
Machines and their cutting tools are not the only things needed for proper machining. Besides using the right processes for each part and the necessary tools, the machining area within the workshop also matters. A workshop must have enough space for the machine tools the work requires; a press, for example, is a large machine that needs suitable space, as the parts machined on it (metal sheets) are large.
By contrast, vertical milling machines and, in general, all machines that work along a vertical axis do not need much longitudinal space. On these machines the movement is upward and downward; on horizontal machines such as centre lathes the movement is always horizontal, along the bed.
But the machining area is not only the space where the machine tools are placed; it is also how they are arranged. To optimise the workshop, and depending on the type of machining carried out there, it is advisable to set the machines up in a circuit, that is, in an order that makes the operators' work easier. This is particularly advisable in factories that produce a limited range of parts on a large scale.
Proper planning can also be a great help in the workshop. It contributes not only to better organisation but also to greater efficiency of both the machines and the operators. That is why it is advisable to keep control of the work and a schedule so that parts can be delivered to the customer within the agreed lead time.
The machine's machining area
Finally, the machining area also refers to the part of the machine where the process of creating the part takes place. The machining area is made up of the table, the bed and the head. Every machine tool is different and operates according to the machining process it carries out. Of the machining processes described above, chip removal is the one that demands the most care of the machining area.
As described above, chip removal produces waste of different sizes and thicknesses that collects on the machine bed. If it is not cleaned regularly, the build-up of swarf can cause equipment failures.
Following a maintenance plan is necessary to improve the performance and service life of the machines. Each machine tool has its own maintenance strategy, which may be weekly (including cleaning the machining area), monthly, six-monthly or annual. The operator can clean the machine and remove the swarf using a dedicated brush.