CNC Machining Steel

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    CNC Machining Steel Services - Steel CNC Machining Part Supplier

    Steel is an iron alloy containing about 1% carbon. To improve its properties, small amounts of other alloying elements such as chromium and molybdenum can be added. Due to its excellent machinability and weldability, steel is an ideal choice concerning low costs and high functionality. However, it will oxidize over time, so a surface treatment is required to protect it.

    At Runsom, we have highly skilled experts who can deal with all your steel CNC machining matters. We can guarantee the accuracy, affordability, and quality of your project components. Specifically, we are capable to process your steel parts with our CNC milling, turning, grinding, EDM, and wire EDM.

    What Is CNC Steel Machining?

    Machining plays an important role in many manufacturing operations. There was a time when this process was completely manual, but it was very laborious and time-consuming. Today, machining services are automated, and one such key application is Computer Numerical Control (CNC) machining. Basically, CNC machining involves using a computer to control the movement of specific tools to form desired shapes and geometries from metal and plastic materials. This automated process is highly popular in manufacturing due to its speed, precision, and productivity. There are several materials that are compatible with CNC machining, and steel is no exception. In fact, CNC steel parts are one of the most typical custom machined components and prototypes.

    Steel CNC Machining Specification






    Its applications can range from structural parts in the construction industry to aerospace-grade parts.


    It is determined by the desired effect and the exact steel used. A tolerance of ±0.005”(±0.13 mm) is available at Runsom.


    Excellent machinability, good weldability, and cost-effectiveness.

    Wall Thickness

    It is mostly decided by the available machine and part geometry. A minimum wall thickness of ±0.03” (±0.8 mm) is available at Runsom.

    Lead Time

    As fast as 3 days, but it will be finally determined by part complexity and order quantity.

    Max Part Size

    The maximum size is mostly decided by the available machine and part geometry.


    3-axis & 5-axis CNC milling.


    Nickel plating, Powder coat, Carburizing.

    Steel Grades We Work With

    Steel is one of the most common manufacturing materials, used in every major industry from automotive to construction. It’s a versatile and cost-effective material full of excellent features. However, choosing the material to use, in this case steel, is only the first step. You also have to choose from different grades. The properties of each steel grade determine their respective uses in specific machining projects. Part of the most common steel grades we offer in CNC machining is as followed:

    Steel 1018

    Commonly referred to as mild steel, 1018 steel is very easy to forge, weld, form, and hot work, which makes it beneficial for products that require severe bending or other delicate features. Therefore, it is often used in applications such as spindles, rods, shafts, or pins. It is also well suited for case hardening processes such as carburizing.

    Steel 4130

    This type is generally recognized as alloy steel due to its increased content of alloying elements compared to normal mild steel. It is a particularly tough steel that is relatively easy to heat treat and highly machinable. 4130 steel is very suitable for the majority of the heat treatment processes. Applications include drills, taps, and aircraft engine mountings.

    Steel 4140

    4140 steel, low alloy steel, very similar to 4130 but with additional carbon content. This chemical composition enhances the toughness, strength, and ductility of this steel grade. Also, the extra chromium makes this grade more corrosion-resistant. Applications include thin-walled pressure vessels, high-strength bolts, and spindles.

    Steel 1045

    Considered medium carbon steel, 1045 steel consists of carbon, iron, silicon, manganese, and sulfur or phosphorus. This is one of the most versatile steel grades manufacturers use for CNC steel parts. Its high strength and toughness justify its use in many CNC steel machining projects where water resistance is critical.

    Steel 1215

    This grade of steel is regarded as free machining steel because of its relatively high sulfur content. Also, many people refer to it as a screw stock because of its usage in automatic screw machine processes. However, the weldability of this material is poor. It is ideal for making screws, pins, studs, and in general, parts that require extensive machining.

    Steel 4340

    This grade of steel is a low-alloy and high-strength metal. It demonstrates incredible strength and toughness and maintains these properties at relatively high temperatures. 4340 steel is often used in typical applications such as shafts, gears, and other structural components.

    If you still have no idea about which steel material is best suited for your CNC machining needs, Runsom just has your answer. We are ready for every challenge and strive for being the best in this industry. Just upload your design file and receive an instant quote, as well as DfM feedback.

    Surface Finishes & Post-Processing Options For Steel Parts

    When the manufacturing process is completed, surface finishing tends to be required to satisfy better functional and aesthetic purposes. To enhance the mechanical properties of steel CNC machining parts, some common surface finishes applicable to steel we offer are shown below:

    CNC machined steel part

    Powder coating is a process involving depositing dry powder on the surface of the steel to form a robust surface finish that is typically between 0.006” (0.1524 mm) and 0.012” (0.3048 mm) thick. This method will improve the corrosion tolerance of CNC steel parts. Bare steel can be beneficial from powder coating as it rusts easily.

    Carburizing treatment refers to a chemical heat treatment process to infuses the surface with additional carbon, where the steel metal is heated in a carburizing medium and kept warm so that carbon atoms penetrate into the surface. This process significantly enhances the hardness and wear resistance of some steels.

    This surface finish involves electroplating steel metal by depositing a 0.1mm layer of nickel on the surface of the part. Carbon steels can be uniformly nickel-plated to improve the tolerance to corrosion and wear.

    This surface finish is employed to remove irregularities and make the surface of CNC machined steel smoother. In general, manufacturers use a grinding wheel to do this.

    Benefits & Challenges of CNC Steel Parts

    In order to produce reliable results every time, properly machining steel parts requires a lot of experience and skill. Although it is a challenge to process steel, the benefit you enjoy from CNC machining on steel is more distinct from its difficulty.



    When it comes to steel alloys available on the market, you will find a large number of steel alloys with good machinability. This means the metal is easily cut or shaped to give a decent result. Factors including hardness, energy, shear stress, and horsepower are closely related to the machinability of CNC machining of steel.

    Another benefit of CNC steel machining of mechanical parts comes with its excellent corrosion and wear tolerance. Moreover, CNC machined steel parts are usually available for many surface finishes.



    When machining steel parts with CNC, there are some challenges and factors to consider despite the benefits mentioned above. First, not all steel parts can be easily machined. As such, this means that certain steel grades may be difficult to use for projects with complex geometries.

    In addition, steel grades have different thermal sensitivities. CNC machining may not suitable for some steel grades since during this process they may melt and become deformed when being greatly exposed to heat.

    CNC Machining Steel FAQs

    While CNC machining processes can manufacture high-quality and precise parts from a wide variety of materials, those that are poorly machinable tend to create results that are not as ideal as wanted. You will find that there are a large number of steel alloys with good machinability when it comes to the wide variety of steel alloys on the market.

    W1 Tool Steel

    W1 is shallow hardened and has great toughness, making it one of the easiest grades to grind and machine. Due to its high carbon composition, it can usually be used without being further heat treated.

    • Place the steel in a forge or heat treatment furnace.
    • Slowly increase the temperature of the steel to meet in a specific austenite region.
    • Hold for 30 minutes at the specified austenite temperature.
    • Slowly reduce the temperature of the steel - how much depends on the grade of the steel.

    Ferritic Stainless Steel - Regarded as the best grade of stainless steel for ease of machining. Ferritic stainless steel includes grade 400. These stainless steels are easy to machine and also have high thermal conductivity and good corrosion resistance.

    Steel is one of the most affordable materials suitable for CNC machining. However, care should be taken to avoid unnecessary machining costs. Here are some cost-saving design tips.

    • Material selection
      While it may seem cheap, it is important to choose the best steel for your specific application. Using high-strength alloy steel that has the same function as mild steel will only increase the cost without any additional benefit.
    • Parts setup
      Designing a part to reduce the number of machining setups can greatly lower manufacturing costs. It’s a truth when machining cheap materials, as any cost savings on the material can quickly be offset by expensive setups.

    Steel and aluminum are two common and compatible metals used in CNC machining. It’s a crucial concern to choose the right one well suited to your project between just these two. A comparison of the CNC steel machining and CNC aluminum machining is shown below:


    Machinability is affected by various factors, including the strength and hardness of the metal. In general, the harder a metal is, the less machinable it is. The same principle applies to aluminum as well.

    Steel has a higher Brinell hardness range (80 and 600) than aluminum (around 15). Also, steel has higher tensile strength and yield strength than aluminum. Therefore, it can be concluded that steel has higher strength but lower machinability.


    Since aluminum is lighter than steel, machinists can work on it faster. Similarly, aluminum cools faster than steel when heated. This means that when processing steel, the manufacturing cycle is longer.


    In most cases, the decision between steel and aluminum boils down to a question of cost. This is, even more, the case when both materials are suitable for a specific project. While these metals come in different varieties and grades, CNC machining of steel generally costs more than aluminum.

    CNC machined steel parts or components can be found in various industries for different applications today, including the electronics, automotive, and medical industry. Specifically, steel CNC machining plays an important role in producing vacuum pressure vessels, gears, and components for medical instruments and machinery.

    Steel CNC Machining Services At Runsom

    The reason why steel is the premier choice for manufacturers in a multitude of industries around the world is its robust physical properties and wide range of applications. An infinite number of possible alloys offer countless steel grades with impressive properties. High-quality machining service is of great significance for your CNC machining steel project after you determine the desired grade of steel material.

    Submit your CAD file online to get started on your steel CNC machining project with a rapid quote today.