Steel is one of the most used metals in the world today. Given the numerous benefits of the metal, this is not at all surprising. In industry, manufacturers utilize various metalworking services to meet product design specifications and requirements.
One such machining service is CNC steel machining. This highly automated process is one of the most versatile ways to produce steel parts. However, several factors play a role in steel processing.
In this article, you will learn everything you need to know about CNC steel machining and the various considerations for achieving optimal results.
What is CNC steel machining?
Machining is an essential process in many manufacturing operations. Previously, this process was carried out completely manually, but it was very complex and time-consuming. Nowadays, machining services are becoming automated and one such application is computer controlled machining (CNC).
CNC machining essentially uses a computer to control the movement of a specific tool and form designs from metal and plastic material. This automated process is widely used in the manufacturing industry due to its speed, precision and production efficiency.
Various materials are compatible with CNC machining and steel is no exception. In fact, CNC steel parts are one of the most popular materials for custom parts and prototypes.
Types of Steel for CNC Machining
The application of CNC machining extends to various materials. Choosing the right material for your project can be difficult and often depends on several factors. However, choosing which material to use, in this case steel, is just the first step. You still need to choose between the different notes available.
The properties of steel types determine their respective use in specific machining projects. Here are some of the most common varieties and their characteristics.
4140 steel
This type is a low alloy steel with little chromium, molybdenum and manganese. This chemical composition improves the strength, ductility and toughness of the steel grade. Furthermore, the additional chromium content makes this type more resistant to corrosion.
Therefore, due to its good machinability and abrasion resistance, it is used in various industries. However, 4140 steel is not as easy to weld and may require pre- and post-heat treatment. This grade is commonly used in CNC steel parts for couplings, spindles, screws, nuts and automotive parts.
Mechanical properties
Yield strength (MPa): 655
Shear modulus (GPa): 80
Elongation at break (%): 19
Hardness (Brinell): 197
Density (g cm-3): 7.87
4130 steel
Compared to normal steel, 4130 steel has a higher content of alloying elements. It is composed of iron, carbon, chromium, manganese, molybdenum, phosphorus, silicon and sulfur. These elements are responsible for the toughness, machinability and heat tolerance of this type of steel.
Due to its ability to withstand high loads, it is often used for various construction purposes. It is also used in aircraft engine mounts. Manufacturers often prefer 4130 steel over aircraft steel because it is cheaper but equally effective.
Although 4130 steel is easy to heat treat, it is not very easy to weld.
Mechanical properties
Yield strength (MPa): 460
Shear modulus (GPa): 80
Elongation at break (%): 20
Hardness (Brinell): 217
Density (g cm-3): 7.87
1018 steel
This type of steel is generally considered a mild carbon steel and is composed of iron, carbon, manganese, phosphorus and sulfur.
1018 steel's biggest selling point in CNC steel machining is its high weldability, making it the standard choice for carburized CNC steel parts. However, please note that welding is only advisable after carburizing.
1018 steel is not only very easy to weld, but also excellent to machine. This is the basis for its use in precision CNC machining processes such as steel turning and milling. In practice, manufacturers use it for tie rods, spindles, shafts and many other mold components.
The biggest disadvantages of this type of steel are its incompatibility with various finishing processes and its relatively high price.
Mechanical properties
Yield strength (MPa): 310
Shear modulus (GPa): 78
Elongation at break (%): 15
Hardness (Brinell): 131
Density (g cm-3): 7.87
1045 steel
This is a medium carbon steel composed of iron, carbon, silicon, manganese and sulfur or phosphorus. This is one of the most versatile steel types that manufacturers use for CNC steel parts. 1045 steel is strong and tough, justifying its use in many CNC steel machining projects where water resistance is essential.
Additionally, 1045 steel is machinable and weldable, which are important factors manufacturers consider when machining steel. Applications of this class include beers, screws, gears, shafts and bolts. Essentially, manufacturers prefer it for projects that require extreme speeds.
Although this type of steel has relatively high strength, its use for very strong products is not advisable because its tensile strength and hardenability are mediocre at best.
Mechanical properties
Yield strength (MPa): 450
Shear modulus (GPa): 60
Elongation at break (%): 12
Hardness (Brinell): 170
Density (g cm-3): 7.87
1215 steel
This type of steel contains iron, carbon, manganese, phosphorus and sulfur. Due to the relatively high sulfur content of this type of steel, it is considered free-cutting steel. Many also refer to it as screw steel because it is used in automatic screw machine processes.
1215 steel forms small chips during machining, allowing for higher machining speeds and preventing machine tangling. However, it is not very easy to weld. Additionally, due to its relatively low carbon content, it is not as strong as other cold drawn grades.
Industrially, it is suitable for automated projects where heavy machining is required. Its areas of application include bolts, pins, screws, couplings and hose connections.
Mechanical properties
Yield strength (MPa): 415
Shear modulus (GPa): 80
Elongation at break (%): 10
Hardness (Brinell): 167
Density (g cm-3): 7.87
Advantages and challenges of CNC steel parts
Correct machining of steel parts requires a lot of experience and skill to always obtain reliable results. Although steel is one of the most demanding materials, the benefits you get from using steel often outweigh the challenges.
Benefits
Most CNC steel parts available today are highly machinable, meaning metals can be easily cut or shaped to produce a perfect result. Factors such as hardness, energy, power and shear stress affect machinability in CNC steel machining.
Another advantage of CNC machining of machine parts is that the products are very resistant to corrosion and wear. Additionally, steel parts are generally compatible with many surface treatments.
challenges
Despite the numerous advantages, there are also some challenges in CNC machining steel parts. On the one hand, not all steel parts can be machined smoothly. This means that for geometrically complex projects it may be difficult to use some types of steel.
Additionally, different types of steel have different heat sensitivities. Some grades are unsuitable for CNC steel parts exposed to high temperatures as they may melt and deform.
Surface finishing and post-processing options for steel parts
As the name suggests, surface finishing is a process carried out after the normal manufacturing of metal parts. The objective is to improve the functionality and aesthetics of these pieces. However, different metals require different surface finishes.
Common surface finishes for steel parts are listed below.
Powder coating
Powder coating involves applying dry powder to the surface of the steel. The coating is generally between 0.15 and 0.3 mm thick. The obvious advantage is that the corrosion resistance of CNC steel parts increases.
Carburization
Carburizing hardens metal surfaces. This process involves heating the steel in the presence of carbon-containing materials such as carbon monoxide and charcoal. In addition to hardness, carburizing also improves the wear resistance of CNC steel parts.
Nickel plating
With this surface refinement, the metallic steel is galvanically coated with a thin layer of nickel (approx. 0.1 mm). This can improve the corrosion and wear resistance of steel parts.
Grind
Grinding smoothes the steel surface and eliminates irregularities. Manufacturers use a grinding wheel for this.
Steel versus aluminum machining: what's the difference?
One of the reasons CNC machining is so widespread today is its compatibility with various metals and even plastics. However, steel and aluminum are the two most common materials for CNC machining. Manufacturers often only have to choose between these two. Below is a comparison between CNC machining of steel and CNC machining of aluminum.
Machinability of steel and aluminum
Machinability depends on several factors, including the hardness and strength of the metal. In general, the harder a metal is, the more difficult it is to work with. This principle also applies to aluminum.
Steel has a higher Brinell hardness range (80 and 600) than aluminum (about 15). Likewise, steel has greater tensile strength and yield strength than aluminum. Therefore, steel is stronger but less workable.
Steel Versus Aluminum Machining: Speed
Because aluminum is lighter than steel, machinists can work on it faster. Additionally, aluminum cools more quickly after heating than steel. This means that longer manufacturing cycles are required when machining steel.
Steel Versus Aluminum Machining: Cost
The decision between steel and aluminum often comes down to price. This is especially true when both materials are suitable for a specific project. Although there are different types and grades of these metals, CNC machining of steel is generally more expensive than aluminum.
What should you choose?
The first factor you should consider is the type of product you need. Steel is best suited for products exposed to high temperatures due to its higher melting point. Aluminum, on the other hand, is better suited for lightweight parts, especially when conductivity is critical.
CNC Steel Parts Applications
CNC steel parts can now be found in many industries, including medical, automotive, and electronics. More specifically, CNC steel machining is useful for medical instruments, machine parts, vacuum pressure vessels, and gears.
CNC steel machining services at Wayken
CNC steel parts are now common in many industries. Before CNC machining steel, manufacturers must decide on the type of steel. To achieve this, the various properties must be evaluated based on the project requirements. After considering all factors, quality editing services are crucial.
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