CNC Vs. Conventional Machining Compared

CNC vs. Conventional machining
CNC vs. Conventional machining

CNC machining has come to be the standard in the manufacturing industry. In this comparison of CNC vs. conventional machining, we look at the differences between the two technologies, their impact on manufacturing, and situations where one may be preferable.

CNC Machining Meaning

Let’s start with the definition of CNC machining. CNC machining is a computer-controlled product or part-making process that automates cutting metal and other materials, such as plastic. The process is overseen by a computer program that tells the machine what to do and how to do it.

This allows for greater precision and repeatability than with conventional machining processes, besides a faster production time.

Additionally, CNC machines can create complex shapes that would be difficult or impossible to create with traditional methods. This and other attributes make CNC machining the preferred method for many manufacturers and art-making processes.

What is the Conventional Machining Process?

Conversely, conventional machining is a product or part-making process that does not use computer numerical control. In other words, with CNC machining, computer programs control the machine tool. In contrast, in conventional machining, the machinist controls the machine tool.

Despite CNC machines being the norm in today’s manufacturing processes, there are still a few applications where conventional machining is the better choice. So it’s not uncommon to find CNC and traditional machining used side-by-side in the same manufacturing facility.

But while both methods have their place, there are some key differences that you should be aware of. These will be discussed in more detail below to give you an idea of what to expect from each machining method or process.

CNC machining
CNC machining

CNC vs. Conventional Machining: 9 Differences

The main difference between CNC and conventional machining is the level of automation and the sophistication of the equipment. With CNC machining, all operations are automated using computer numerical control (CNC) technology. That means that the machinist does not need to be present to operate the equipment. Here is a closer look at these differences.

CNC vs. Conventional Machining: Accuracy

Because it’s computer-controlled, CNC machining can achieve much higher levels of accuracy than conventional machining. CNC machining tolerances can be +/-0.005 inches or better. In contrast, conventional machining can only achieve lower tolerances, given that the various controls are manual.

CNC vs. Conventional Machining: Replication

Another different between CNC and conventional machining is the ability of CNC to produce identical parts time after time. That’s because the computer program can be easily duplicated and the machine will produce the same results each time it runs. With conventional machining, it’s more difficult to achieve this level of replication because the process is not automated.

CNC vs. Conventional Machining: Ease of Use

While CNC machines are more complex than conventional machining equipment, they are much easier to use. Once the program is written, the CNC machine can be left to run on its own. This frees up the operator to do other tasks. With conventional machining, the operator must be present to oversee the operation of the machine.

CNC vs. Conventional Machining: Geometry

CNC or non-conventional CNC machining, depending on the type of machine, can produce very complex shapes and a geometry that would be impossible to produce with conventional machining methods. This is due to the fact that CNC machines are able to move the cutting tool in three dimensions. Conventional machining equipment is only able to move in two dimensions.

CNC vs. Conventional Machining: Cost

The cost of CNC machining can be higher than conventional machining because of the need for specialized equipment and training. However, the increased accuracy and repeatability of CNC machining often offset the additional cost. In addition, the price of CNC machines has been dropping in recent years, making them more affordable for manufacturers.

CNC vs. Conventional Machining: Speed

Everything about CNC machining is largely automated. This means the machine can run for longer periods of time without stopping to rest. On the other hand, with conventional machining, the operator must take breaks to avoid fatigue. That means that the overall production time can be longer.

CNC vs. Conventional Machining: Safety

One of the main differences between conventional and unconventional machining is that CNC is generally considered to be a safer process than conventional machining because the operator is not present when the machine is running. That means that there is less of a chance for an accident to occur. In addition, CNC machines are designed to stop automatically if there is a problem, which further reduces the risk of injury.

CNC vs. Conventional Machining: Labor

The CNC machine process requires less labor than conventional machining once the machine has started. Before that, there’s usually the computer program to write and the machine to set up. Once these tasks are completed, the machine can be left to run on its own.

In contrast, conventional machining requires more labor because the operator must be present to oversee the operation of the machine. They may also need to make adjustments during the machining process.

CNC vs. Conventional Machining: Application

The application of CNC machining includes situations where high levels of accuracy and repeatability are required. Examples of such applications are aerospace, the automotive world, and in the production of medical devices.

In contrast, conventional machining is more suited for applications where lower levels of accuracy are acceptable. These include machines to shape wood, machines to cut metal to required designs, and so on.

CNC machining metal workpiece
CNC machining metal workpiece

Advantages of CNC over Conventional Machining

Given the above comparison, what are the advantages of CNC over conventional machining? In summary, the main differences between CNC and conventional machining are:

  • The level of automation.
  • The sophistication of the equipment.
  • The accuracy of the process.
  • The ability to replicate parts.
  • The cost.

However, as mentioned earlier, some situations don’t call for the high levels of accuracy and repeatability that CNC provides, making conventional machining the more appropriate choice.

Ultimately, it’s essential to choose the right type of machining for the job at hand. We must add that the CNC machining process is way safer when compared to conventional machining. This is due to the increased level of automation, which reduces the chances of human error or contact with machining tools.


CNC machining is the preferred technology in the manufacturing industry for many reasons. It offers greater accuracy, repeatability, and automation, among other advantages. That being said, simpler applications such as woodworking and metalworking may still be suited for conventional machining, given its cost-effectiveness and lower skill requirements. Conventional machining may also suit one-off projects or prototyping before full-scale production.

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