Advantages and disadvantages of CNC machining
CNC machining has gradually become mainstream in the manufacturing industry because it is more efficient than using manually operated machines. Listed below are some of the pros and cons of CNC machines.
| Advantages | Disadvantages |
| Faster than manual operation | Machines are expensive |
| Manual operation cannot match CNC machines in speed and accuracy. In a high-volume production environment, using manual machines will only lead to financial losses | CNC machines are very advanced equipment with very high tolerances and rigidity. It enables users to manufacture millions of parts with guaranteed high quality. But high quality also means high cost; and the more advanced the machine, the higher the cost. |
| Reduced production costs | Requires highly skilled operators |
| If the loading and unloading of materials is further automated, CNC machines will be able to run continuously without the need for human supervision. Additionally, one operator can operate multiple machines, offsetting higher labor costs. | Although fewer operators are required, CNC machines require highly skilled operators, which also increases labor costs. |
| Improved production efficiency | Increased maintenance costs |
| CNC machines can switch from one operation to the next in less than a second. Changing tools can be done very quickly as some machines have many tools pre-installed on the turret or have tool magazines that can load new tools onto the spindle when needed. | Due to the complexity of CNC machines, their maintenance costs are much higher than manual machines. |
| Improved security |
Material
CNC machines are capable of processing a variety of materials, from aluminum to high-temperature alloys such as Inconel. Each material presents its own set of challenges, requiring specific tooling, speeds and feed methods.
Aluminum
Since aluminum is a very soft metal, there is a risk of it sticking to cutting tools. Given the low melting point of aluminum, proper tempering of aluminum to increase its hardness can improve its machinability.
Carbon Steel
Since steel is divided into many grades, many factors can affect the overall workability of the material, such as cold work, chemical composition, microstructure and other factors. Generally speaking, elements such as lead and tin increase cutting speeds due to their lubrication effect, and sulfur reduces strain hardening of the chips.
Titanium
Titanium is available in many alloy types, each with its own challenges. Ideally, the tool must be in constant interaction with the material, as remaining in one area will lead to friction, heat build-up, work hardening and tool wear. Pure titanium has properties similar to aluminum and will stick to cutting tools, but its alloys are generally harder, which can lead to heat buildup and tool wear. Low RPM and high chip loads extend tool life because temperatures are lowered.
Superalloy
Superalloys are very strong at high temperatures, making them difficult to machine. To process such materials, more powerful machines are necessary. High-temperature alloys quickly undergo work hardening, making subsequent machining more difficult. It is generally recommended to keep cutting speeds low.
Copper
Copper is a notoriously difficult material to work with because it is malleable and often curls around tools, making it impossible to cut. It is mainly used in power components and heat exchanger components that require high electrical conductivity and high heat transfer coefficient. For pure copper, high-speed feed can usually be used. Copper alloys are much easier to process than pure copper.
Plastic
Plastics come in thousands of varieties, ranging from thermosets to common thermoplastics. Plastics also vary widely in their hardness and mechanical properties. Only rigid plastics process well and stay within tolerances, while soft plastics often deform as they pass through the cutting tool, causing the part's outer dimensions to fall out of specification. Since plastic is an insulator, heat often builds up at the cut edges and the plastic will melt if you are not careful.
