What is the best type of Mild Steel in CNC Machining?

Mild steel is popular in many engineering applications due to its low cost, ductility, and durability. CNC machining is a process where parts can be manufactured from either metals or plastics, and mild steel’s superior malleability makes it an ideal material for CNC machining.

This blog will uncover the different types of mild steel CNC machining and discuss which type is the best for the job. 

We’ll also explore the pros and cons of using the best type of mild steel in CNC machining, including their suitability to various shapes, corrosion resistance, strength, and other mechanical properties that make them suitable for specific applications. Types 1-5 will be covered in more detail below.

What is Mild Steel?

Mild steel is a type of carbon steel alloys that has an alloying element added for strength and malleability. It contains less than 3% carbon and up to 1% manganese, which increases its hardness and tensile strength. However, remaining ductile enough to be machined or formed into various shapes and components. 

Mild steel machining is often used in applications where greater flexibility or cost savings are desired over other materials, such as stainless steel, due to its low cost, wide availability, ease of fabrication, good weldability, formability, and corrosion resistance properties. 

Additionally, mild steel alloys can undergo heat treatment to increase their wear resistance and tensile strength, making them suitable for many engineering applications such as automotive parts, agricultural equipment, construction machinery frames, and more.

The Pros of Using Mild Steel in CNC Machining

Mild steel is an ideal material for CNC machining due to its low cost, malleability, and durability. Its superior malleability makes it possible to produce intricate parts in a wide range of shapes and sizes with accuracy while still allowing for high levels of customization. 

Additionally, mild steel has excellent corrosion resistance properties, making it suitable for outdoor use or applications involving chemicals or other corrosive materials. Furthermore, the strength of mild steel can be increased through heat treatment, making it an ideal choice when higher wear resistance is desired. 

Mild steel alloys’ versatility also allows them to be used in various industries, such as automotive manufacturing, construction machinery fabrication, and agricultural equipment production, where precision and durability are requirements. 

In summary, mild steel offers great advantages over other materials when used in CNC machining due to its low cost, malleability, durability, and versatility, making it one of the most popular choices among engineers today.

The Cons of Using Mild Steel in CNC Machining

The vibratory finishing process involves putting parts, media, and compounds in a vibrating tub or bowl. A mass of pieces is deburred or polished by the media, and parts turn and grind against each other due to the vibratory action.

Mild, plain carbon steels are popular for CNC machining projects due to their strength and durability. It’s relatively inexpensive, easy to form into complex shapes, and can be used in various applications. However, there are some drawbacks associated with using mild steel in CNC machining that you should consider before deciding if it’s right for your project. 

For instance, it has limited corrosion resistance, so it may need additional protection when exposed to moisture or other elements. Additionally, while mild steel is strong enough to handle high-speed operations and extreme temperatures, the material can wear down over time. This is mainly due to friction from moving parts during operation. 

Each project requires careful evaluation of the pros and cons of using mild steel to determine whether it’s the best option for your specific needs.

Tips to choose the Right Mild Steel for Your CNC Machining Project?

Choosing the right mild steel for your CNC machining project can be tricky. But with the right knowledge and research, it doesn’t have to be.

First, consider the type of application you are working on – are you looking for something strong and durable? Or perhaps something easy to shape into complex designs? Different types of mild steel have different benefits, so compare them before settling on one. 

Consider any potential drawbacks associated with each type. Thus, some may require additional protection when exposed to certain elements or temperatures, while others may not hold up well under high-speed operations. Ultimately, carefully considering these factors will help you select the best mild steel for your CNC machining project.

In conclusion, mild steel is an excellent material for CNC machining due to its durability, machinability, and moderate price. Among the different types of mild steel available for machine use, Steel S355J2 provides the best strength and cost efficiency for most manufacturers. 

This type of stainless steel can be used in various applications that require precision cutting and has several advantages, such as increased resistance to corrosion and higher load capacity compared to other materials. 

Therefore, this makes it one of the best choices available for achieving a successful outcome in CNC machining projects with mild steel.

Best Types Mild Steel in CNC Machining

It depends on your specific project and requirements if you’re looking for the best type of mild steel to use in CNC machining. Generally speaking, one of the most popular types is low-carbon steel due to its strength and durability.

It’s also relatively inexpensive compared to other materials like stainless steel or aluminum. Additionally, it can be easily formed into complex shapes, making it ideal for creating custom parts and components with precision and accuracy.

Other common types include medium carbon steels, high-strength low alloy (HSLA), ultra-high-strength steels (UHSS), and cold rolled steels, each with their advantages depending on your need. Here are some of the best types of low-carbon mild steel. 

Type1: Mild steel 1018

The ideal plain carbon steel for carburized parts is 1018 mild/low carbon steel, which has great weldability and produces a uniform and tougher casing. This material has an excellent balance of toughness, strength, and ductility. 

The mechanical properties of AISI 1018 hot rolled steel are noteworthy, with better machining capabilities and a high Brinell hardness measure.AISI 1018 hot rolled steel also has great hardenability, which makes it useful for carburizing and other heat-treating processes. 

It also has good fatigue resistance and can be used for parts that require wear resistance. This type of steel is also highly affordable and easy to work with, making it an ideal choice for carburized parts. 

Type 2: Mild steel A36

A36 is a low-carbon steel with a  carbon content of less than 0.3% by weight. As a result, it can be easily machined, welded, and shaped, making it excellent general-purpose steel. Because of the medium carbon steel content, heat treatment has little effect on A36 steel.

Typically, this free-machining steel material contains trace amounts of other alloying elements such as manganese, sulfur, phosphorus, and silicon. These alloying elements are added to A36 steel to provide it with the appropriate chemical and mechanical qualities. 

A36 has poor corrosion resistance because it lacks significant nickel and chromium concentrations. 

Type 3: Steel S355J2

Steel grade S355J2 shows good impact toughness at -20oC, making it suitable for applications with critical low-temperature performance. 

It has a yield strength of 355 N/mm2 and a tensile strength of 510-680 N/mm2. It can be cold-formed and welded using either manual or automatic welding techniques. 

The steel has excellent corrosion resistance, particularly when exposed to chloride-containing atmospheres, just like stainless steels. To further improve its corrosion resistance, it can be galvanized and painted. The mechanical properties of this grade of steel can be enhanced through different series of heat treatment, like tempering, quenching, and normalizing. 

Type 4: Steel S235JR

Steel grade S235JR is a prominent non-alloy structural, building services, and machine steel that meets the EN 10025-2 standard. It is one of the most commonly used hot-rolled general structural steel grades, with a minimum yield strength of 235MPa.

S235JR is widely used in the construction and engineering industries for its high strength and excellent corrosion resistance.

It also has good weldability, formability, and machinability characteristics.

Type 5: S275JR steel

S275JR steel is low-carbon manganese steel that is easily weldable and has strong impact resistance. This material is frequently offered untreated or normalized. This material’s machinability is comparable to that of mild steel. The chemical composition of S275JR steel is as follows: Carbon (C) – 0.2%, Manganese (Mn) – 1.5%, Silicon (Si) – 0.3%, Sulphur (S) – 0.03%, Phosphorus (P) – 0.04%. It is also non-alloy and can be used in various applications such as bridges, ships, vehicles, and construction equipment.

S275JR steel has good tensile strength and can be heat treated to harden it. It is a suitable grade for welding because it has a lower carbon steel content and provides good weldability. It can be cold bent, formed, and cut easily, making it a popular choice for making structural frames.


Low-carbon steel is the most common type of mild steel used in CNC machining. This type of steel has a medium carbon steel content, which helps to decrease the hardness and increase the material’s malleability. Low-carbon steel is ideal for machining because it can be bent, shaped, and formed into various shapes and sizes. Low carbon steels have excellent weldability and is a good choice for components that must be joined together. It is also an affordable option for CNC machining and can often be produced at a much lower cost than other metals.

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