July 22, 2021
Officine Meccaniche Marcucci specializes in precision mechanical turning with numerical control machines, we deal with the turning of mechanical parts from single pieces to batches of medium series.The processes possible today on CNC lathes are the following
• External, internal and shoulder cylindrical turning
• Parting and profiling with form tools
• Facing
• Drilling and reaming
• Conical turning
• External and internal thread
• Spherical turning
• Knurling
• Slotting
EXTERNAL, INTERNAL AND SHOULDER CYLINDRICAL TURNING
The internal and external cylindrical turning for machining mechanical parts is performed to give the component the desired diameter.
First, roughing is carried out using a tool specifically for this process, preferably with a sustained radius to facilitate chip removal
To perform this operation in an optimal way, it is necessary to leave an allowance of about a few tenths, this allows the parts built according to the drawing to access the next phase, that is the dimensional finish using a so-called finishing tool with a smaller radius.
Shoulder turning is a type of machining that allows the execution of wide grooves and the most common methods for performing a shoulder include multiple-pass grooving, plunge profiling and inclined plane machining
SPHERICAL TURNING
To carry out spherical turning in the production piece machined mechanically on CNC lathes, a specific tool must be used to be mounted in place of the standard turret.
The height of the cutting tip must be adjusted on the axis of the lathe tips, in the same way the center of rotation of the bearing wheel will lead the tool to the center line of the piece.
Today, this type of processing is facilitated by the aid of cad-cam programs that allow it to improve its execution, also taking into account the tool geometry
CUT OFF
Parting is a type of processing that serves to separate a finished piece from the original bar to which it belonged
The piece is turned up to its axis, that is, until it assumes a diameter of 0.
To carry out the parting off, specific tools are required, known in jargon as parting offsets
FACADE
Facing consists in turning the piece mechanically machined on CNC lathes up to its axis, to make it assume the defined dimensions.
In this operation, the tool moves radially along the end of the mechanical part in small and medium series, removing a thin layer of material in order to obtain a smooth and flat surface. In facing, the advancement of the tool is transversal in order to minimize vibrations, the speeds of use vary from the type of material used and the type of insert used
INTERNAL AND EXTERNAL THREADING
Machine threading compared to traditional or manual threading is a very useful operation because it ensures the tool can disengage and allows the screw to be screwed against the shoulder or at the bottom of a hole, and also avoids the formation of burrs in the section a incomplete fillet
To obtain a thread it is necessary for the lathe to advance by an amount equal to the thread pitch to be made at each revolution of the piece.
The speeds of use and feeds vary according to the type of material used and the type of insert used
SLOTTING
It is possible, through a tool called motorized slotting machine, to be able to carry out certain machining operations on a CNC lathe, ranging from a simple keyway to internal or external toothed profiles.
This type of tool was built to obtain maximum rigidity, allowing for a very prolonged use of the insert and an excellent degree of finish on the machined surface.
The use of this type of tool offers great advantages: in addition to being extremely quick in performing the machining, it does not require the movement of the piece on other machines
FINISH
With finishing operations, the result is achieved by passing through the roughing phase which serves to remove the bulk of the metal and is carried out using tools that withstand significant stresses. After roughing, you will perform the finishing process where a limited portion of material is removed. Finishing is, in fact, the phase that returns the expected product: for this step, very high precision machinery must be chosen in which the right cutting speed and the adequate number of revolutions are set, managing to obtain mechanical parts built to design
KNURLING OR KNURLING
With knurling, a series of grooves are produced on mechanically processed pieces by CNC lathes, creating a cylindrical surface and making the surface rough. This type of processing makes it possible to improve its grip on those parts that must be handled manually
Generally the tool used for this type of processing is the "knurl" UNI 5599, which is pressed against the surface of the piece and rotates at high speed making it possible to create the mechanical part even in a single working day.
The speeds of use and feeds vary according to the type of material used and the type of insert used
Once all the turning processes have been defined to create mechanically machined design parts even in a single working day, Officine Meccaniche Marcucci illustrates what the different cutting parameters can be, which include:
• Advancement: represents the distance that the tool covers with respect to the workpiece during a spindle revolution
• Cutting speed: it is the speed that reaches the surface of the piece with respect to the edge of the cutting tool during the machining phase
• Spindle speed: is the spindle rotation speed measured in revolutions per minute and is obtained by dividing the cutting speed by the circumference of the workpiece. In order to keep the cutting speed constant, this variable must vary according to the cutting diameter
• Feed rate: it is the straight feed speed of the tool with respect to the workpiece, to obtain it you need to multiply the cutting speed by the spindle speed
• Axial cutting depth: measures the depth of the tool along the axis of the workpiece during the execution of a cut
• Radial cutting depth: defines the cutting depth of the tool measured along the radius of the workpiece during turning
There are many lathe tools on which you want to invest and they differ according to the greater or lesser possibility of obtaining the required finishes and therefore their quality.
The material is one of the elements to be considered according to parameters concerning hardness, the ability to resist without breaking, wear resistance and the possibility of low heating during processing.
Today The technology of turning machines allows us to achieve high results both in terms of precision and processing speed, thus managing to satisfy all customer needs.
Our challenge is to satisfy all the requests that are placed on us, including that of delivering the finished product "all included" in just one working day.
