A machine tool is a machine created to modify the shape and size of an object. Its main mode of operation is the selective removal of excessive material through the use of tools, until the required shape is obtained. The pieces can be of various types, but most commonly they operate on steel or wooden parts.
These machines find fertile ground in the manufacturing and mechanical industries thanks to their use of motion energy: they do not rely on human-generated power, and this optimizes the workflow.
The operations of the machine tool employ three different motions:
- Work motion: This has two different ways of operating. The first one involves the piece moving around the tool, which is in a fixed position (centre lathes). In the second case, the moving part is the tool, which works on a fixed piece (milling machines or drill-mills)
- Feed motion: this one allows different parts of the machine to operate, providing energy by means of V-type belts or electric motors to the shaft of the tool.
- Location motion: this determines the depth of the run, which is the precise amount of material that needs to be removed each time the tool operates on the part.
Machine tools can be subdivided according to two selection criteria: one according to the type of work motion they perform, while the second one refers to the result that can be obtained from the machine.
For the first criterion there are two classifications, a general one and a more specific one. The first one determines:
- Movable part machine tool: the movement is performed by the worked piece, whereas the tool is in a fixed position and can only move sideways or tranversely.
- Movable tool machine tool: here the tool is the only part which moves around to work on the piece, and in this case the piece is always fixed in place.
The second classification identifies four machine types:
- Even rotary motion machine tool;
- Alternated rectilinear motion machine tool;
- Special motion machine tool;
- Variable rotary motion machine tool.
And lastly, the classification based on the achievable individual production:
- Universal machine: if the machine can perform various operations and can be controlled both manually or numerically;
- Big volume machine: if it can be used to produce a large quantity of pieces by engaging various tools at the same time;
- Transfer machine: if it is made up of multiple stations on which the parts are transferred, depending on the operation to be executed;
- Special machine: if the machine is created to perform a single type of operation;
Combined machine: if it is made up of the combination of multiple special machines working on a fixed piece.
No matter their type, machine tools are built with four main components:
Lower frame – Electric motor – Headstock – Shafts
When using the term “lower frame”, we identify the base of the machine tool. This part must have a heavy weight in order to make the machine stable and resistant, and this is a fundamental feature: whenever the machine is operative, the base has to withstand many vibrations and strains, which could compromise the quality of production.
On the machines there usually are one or two electric motors. Their job is to transform electric energy into mechanical energy, so to provide power for the various motions and according to the different operations.
The headstock, together with the transmission, transfers and regulates the power given to the spindle. By changing the settings, the technician can adapt the rotations and consequently the speed of the tool, to better adapt it both to the types of operations and to the material of the parts.
Shafts are components which transfer motion by rotating. They are divided into:
- Driving shafts: these are directly connected to the rotor of the electric motor;
- Driven shafts: these are connected to the driving shaft by means of specific transmission gears;
- Final driving shaft or spindle: it directly provides the work motion. On this part, clamping gears for either the tool or the piece are mounted.
Sinico Company actively operates in the mechanics sector ever since 1962. Therefore, we decided to share some of the notions we have learned during this time. Shortly, new articles will be released, so stay tuned for more information revolving around the world of the machine tool and mechanics.