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All about CNC machining

Paul Gardette

What is CNC machining?

CNC (Computer Numerical Control)machining, also known as precision machining, is a technology that forms an integral part of the manufacturing process for mechanical parts. 

Used in many industries, this manufacturing technique uses intelligent machine tools driven by computerized controls to machine parts. CNC machining makes it possible to go from raw parts to high-precision, mass-produced custom parts.

CNC machining works on the basis of a program, based on a 3D model of the part, which will indicate the important steps to be followed by the machine tool, in detail (speed, movement, choice of tool, etc.). 

This partly automated process step has its place inIndustry 4.0, enabling the creation of extremely precise parts and the production of one-off small, medium and large production runs. This is micro machining.

What is CNC micro-machining?

CNC micro-machining is a combination ofprecision machining and traditional machining. CNC micro-machining is generally used for highly complex machining operations requiring extreme precision and tolerances.

CNC machining and CNC micro-machining take the same approach. 

The only difference lies in the precision of their operations: 

  • CNC machining most often involves removing layers of material from a blank, such as milling (cnc milling) and turning (cnc turning).
  • Whereas CNC micro-machining requires "miniaturized" tools of greater precision for parts with higher requirements.

The use of miniature tools means that machining operations can be very small, down to the micron, sometimes almost invisible to the naked eye. At LGC Industries, we master both CNC and micro machining.

Why choose CNC machining?

Precision machining is an important step in the manufacturing process, and can be replaced by traditional methods such as conventional machining, but this prototyping and manufacturing technique offers a multitude of advantages:

  • Precision:CNC machining produces parts with ultra-precise dimensions and tolerances.

  • Flexibility : CNC machining has the advantage of being able to adapt to a variety of materials, offering great flexibility. What's more, this technology makes it possible to produce complex shapes that would be difficult to achieve with conventional machining.

  • Speed : integrated into Industry 4.0 technologies,precision machining combines speed and efficiency in its use, enabling the rapid production of flawless parts.

The positive impact of CNC machining in the industrial world 

Before the invention of this technology, manufacturing processes were predominantly manual and required a great deal of labor on the part of workers, making them difficult or even laborious. 

In 1952,precision machining was born thanks to Richard Kegg and his collaboration with MIT (Massachusetts Institute of Technology) on the first CNC milling machine. 

Between the 1960s and 1980s, CNC machine tools and precision machining took shape, thanks to digital technology that made the automation of production processes much more efficient. In the space of 25 years : 

  • The precision ofCNC machining has improved significantly
  • Programming is easier and more complete
  • Manufacturing times are accelerated, improving manufacturers' productivity at many stages of the process. 

Today, precision machining has become an essential element in the industrial world, as it has the capacity to meet dimensional tolerances in fields of activity requiring the greatest vigilance, such as medical, aeronautical and arms industries...

How does LGC integrate CNC machining into its industrial manufacturing process?

This cutting-edge technology fits perfectly with our strategy of continuous improvement in quality, efficiency, precision, production and customer satisfaction. 

Thanks toprecision machining, we can get even closer to our primary objective: "Getting it right first time".


To further improve precision, cost, quality and lead times, we combine precision machining with other CNC machining processes at various stages of our production process.

The CNC lathe, an example of precision machining

CNC turning is a highly precise machining process based on the principle of the traditional lathe. It involves placing the cutting tool against a turning part to remove material and thus give the desired shape to a part by material removal.

When the CNC lathe starts up, it rotates the workpiece along a double axis movement, and a pointed cutting tool then comes into contact with the material, enabling it to be shaped. In the case of the CNC lathe, computer programs are used to control the center, ensuring the production of extremely precise components.

Traditional tour at LGC

The difference between CNC turning and CNC milling

Many people confuse CNC turning with CNC milling, but there is a clear distinction between the two.

  • In CNC milling, as in most other CNC machining processes, the workpiece is usually clamped to a support while a moving tool shapes it. 
  • On a CNC lathe, it's the other way round: the workpiece rotates while the material removal tool remains stationary.

How CNC turning works : 

  1. Rotation of the workpiece is controlled by the CNC lathe spindle, offering a choice of speeds for optimum precision.
  2. The carriage moves to position the workpiece in relation to the cutting tool, ensuring precise cutting.
  3. The tool's cutting depth is precisely adjusted by moving the cross-member.
  4. The cutting tool now moves to perform the machining operations indicated in the programming.


The combination of tapping andCNC mach ining is a fast, cost-effective process that is fully integrated into the LGC production process, producing a series of taps. This process is used, for example, in the manufacture of our Intervis® slotted thread inserts.

To carry out CNC tapping , the CNC machining center must first be set up and programmed, ensuring that all important factors are taken into account (depth, speed, etc.). Once programmed, tapping of a series of parts can begin, and this operation will be fully automated.

The spline by CNC machining

The combination of splining andCNC machining is a process that makes it possible to produce splines on parts automatically.

Splines are parallel grooves on the workpiece, usually in the longitudinal direction. The mechanical splines are produced by the splining machine on the CNC lathe.

The creation of a spline requires programming of the splining machine, which must take into account : 

  • Part positioning
  • The trajectory of the tool making the splines
  • Groove depth
  • Rotation speed 
  • As well as the tool's forward speed. 

Once the programming has been completed, the splining of a series of parts can begin, and this operation, in which we are experts, will be fully automated. 

Example of a spline operation: the splined pin.

Bar turning by CNC machining

The combination of bar turning andCNC mach ining is a process that produces automated bar-turned parts. 

For CNC bar turning, it is necessary to program the machine tool, taking into account : 

  • The speed at which the main spindle rotates the material bar
  • Part positioning
  • Cutting tool trajectory
  • The depth of bar turning

Once the programming has been completed, the bar turning of a series of parts can begin, and this operation will be fully automated. 

Example of a bar turning operation: the turned pin.

The contribution of CNC machining at LGC

We are proud of our 85 years of expertise in cylindrical fastening solutions. We do everything we can to help our customers work together to design products tailored to their specific needs. 

We are available to support you at every stage of your project and offer you a personalized, high-quality service. 

Innovation and continuous improvement are part and parcel of our core values. At the service of our customers, we master CNC machining to guarantee automated production of mass-produced parts, combining speed and quality.

If you have any questions or would like to find out more about our products and services, please do not hesitate to contact us

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