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How to find the most suitable steel for CNC machining?

Precision CNC machining is a technology for manufacturing parts with precise dimensions. It is often used to manufacture complex parts in industries such as aerospace, automobiles, and modern electronics. With the development of advanced technology and the continuous improvement of processes, it is very important to choose the right material to achieve high-precision machining of parts. Generally speaking, materials used for precision CNC machining need to have dimensional stability, machinability, ease of processing, corrosion resistance, and impact resistance. There are many commonly used materials, but not all materials are suitable for your application. To choose the right material, it is important to understand their characteristics and uses. This article mainly explains how we should find the most suitable steel material for CNC machining.

Steel is by far the most widely used material in the world. To choose the best steel material for your part, you should first understand the characteristics of each steel. Now let’s take a look.

What is steel?

Steel, including carbon steel and alloy steel, is one of the most widely used materials in the world. Steel is known for its high hardness, good toughness, wear resistance and good weldability, and is ideal for high stress, wear and impact parts.

Carbon steel is made of iron and carbon. The main component of steel is iron. Iron is very soft and generally not used as an engineering material. A small amount of carbon needs to be added to strengthen it and transform it into steel. Carbon plays a key role in mechanical properties. The higher the carbon content, the higher the hardness. Steel can be divided into three major categories: low carbon steel with a carbon content of 0.05-0.19%, medium carbon steel with a carbon content of 0.2-0.49%, and high carbon steel with a carbon content of more than 0.5%.

Alloy steel is made by adding alloying elements other than carbon (such as Si, W, Mn, Cr, Ni, Mo, V, Ti) to change the wear resistance and corrosion resistance of steel, which means that the performance of the part can be optimized by selecting the right alloy according to the specific application. Obviously, the wide variety of steels and complex properties pose a challenge to designers in choosing the right steel.

Methods of steel selection

The selection of steel for CNC machining needs to consider many factors, such as the external force applied to the part during use, the characteristics of the part design structure, and the hardness required for the part. Therefore, it is necessary to select the appropriate steel material according to the specific situation of the part.
First, it is necessary to determine the mechanical properties of the required steel, such as strength, toughness, and hardness, based on the structural characteristics and working principle of the part. Then, by comparing the performance indicators of different materials, the most suitable steel material can be selected.

How to choose the parameters of CNC lathe steel material

When rough turning, the cutting depth is 2-5mm in diameter (58MM50 long material) F=0.2-0.4mm/rev;
The cutting depth of fine turning is 0.5-1mm, and the feed speed is F=0.1mm/rev;
304 stainless steel is softer than 404, rough machining 0.8, speed 800-1000, rough machining 0.1, speed, 200-1800, after reaching the depth, the speed is adjusted to 2000;
When cutting, the number of revolutions cannot be too high. The cutting speed is generally controlled at 50 meters/minute, and the 58 circle is about 300 revolutions. As for turning the outer circle, it can be appropriately increased to 80-100 meters/minute.
1Cr13 is a common stainless steel. What should be paid attention to during CNC machining is that the coolant should keep up. The rake angle and chip breaker of the tool should be opened as large as possible to ensure smooth chip removal and avoid the formation of tool nodules. Affect the accuracy of the workpiece.

Processing austenitic stainless steel:
Fine turning V=67~120 m/min, f=0.15mm/r.
Rough turning V=58~105 m/min, f=0.3~0.4mm/r, ap=2~4mm.

In addition, 304 austenitic stainless steel 0Cr18Ni9 should be considered a difficult-to-process material. The hardness is not too high, between HRC15-20. But it is very difficult to process, and the coolant must be evenly kept up during CNC machining. In addition, the number of revolutions cannot be too high when cutting. The cutting speed is generally controlled at 50 m/min, which means that 58 circles are about 300 revolutions. As for turning the outer circle, it can be appropriately increased to 80-100 m/min.

When rough turning, the cutting depth is 2-5mm in diameter (58MM50 long material) F=0.2-0.4mm/rev

The cutting depth of fine turning is 0.5-1mm, and the feed speed is F=0.1mm/rev

1Cr13 is a common stainless steel. When machining with CNC machines, you should pay attention to the coolant. The front angle and chip breaker of the tool should be opened as large as possible to ensure smooth chip removal and avoid the formation of tool tumors. Affect the accuracy of the workpiece. Other aspects can be processed in the same way as carbon steel.

Commonly used steel types for CNC machining

Q235 is a low-carbon steel with high plasticity and low strength. It is widely used in mechanical parts with low performance requirements, such as instrument parts, pins, washers, pipes, joints, etc.

AISI1045 is a medium-carbon steel that can be quenched to HRC42~46. It has good mechanical properties and is often used to manufacture mechanical parts such as shafts, gears, high-strength bolts, etc.

AISI4340 4340 alloy steel has the characteristics of high strength, good toughness, good weldability and good machinability. It is often used to manufacture structural parts such as power transmission gears and shafts, aircraft landing gears, etc.

There are many types of high-strength low-alloy steels, and the common ones are Q295, Q345, Q390, Q420 and Q460. These steels have high strength, good corrosion resistance and relatively low cost.

Free-cutting steels are usually classified by their sulfur content and are usually designated as AISI 11 or 12 series. Examples include AISI 1215 and AISI 12L14. These steels have good machinability and are easy to machine. They improve chip formation and reduce tool wear.

Another category is wear-resistant steels, which are often used in applications where wear and abrasion resistance are critical, such as mining and construction equipment. Some common grades include AR400, AR500, and Hardox.

Bearing steels are high-carbon chromium alloy steels that have high hardness, wear resistance, and fatigue strength, as well as good dimensional stability. Common grades include AISI 52100, AISI 8620, and SAE 52100.

Electrical steels are designed for electrical applications, such as transformers and motors. Some common grades include AISI 1010 and AISI 1020. These steels have high magnetic permeability and low electrical conductivity.

Tool steels: Tool steels have high hardness, wear resistance, and toughness, as well as good dimensional stability. Some common grades include AISI D2, AISI A2, and AISI O1. These steels are often used for cutting tools, dies, and molds.

But steel will rust immediately when exposed to moisture and air, so steel parts are usually treated to prevent rust, such as oxidation blackening, electroplating, coating, etc. In order to improve the rust resistance of steel, people have developed a special alloy steel – stainless steel. One of the great advantages of this metal is that it does not rust.

Differences between stainless steel grades

SS301, SS302, SS303, SS304 stainless steel has excellent rust resistance. SS304 is the best one for rust resistance. It is often used for metal plates, food processing equipment, kitchen utensils and housings.

SS316 has higher corrosion resistance than SS304 because it contains molybdenum, making it a popular choice for manufacturing ships, medical parts, food processing equipment.

SS420, SS430, SS440C stainless steel is a high carbon martensitic stainless steel. It can be heat treated to obtain high strength, good hardness and wear resistance. It is often used to manufacture aircraft parts, medical parts, blades.

SS630 (17-4PH) is a martensitic precipitation hardening stainless steel that can be solution heat treated to achieve high strength and hardness. It is often used in petroleum and chemical, papermaking and marine fisheries.

2205 duplex stainless steel is one of the most common duplex stainless steel grades. It is almost twice as strong as austenitic stainless steel and is often used in high pressure and highly corrosive environments.

Summary

In modern manufacturing, CNC machine tool processing technology is an important tool in the field of processing. CNC machining can achieve high-precision and high-efficiency processing methods, greatly improving product quality and production efficiency. However, choosing the right material is crucial for the parts to be processed. Because the correct selection of the required materials for machining is the key to improving processing quality and economic benefits. Therefore, when selecting CNC machining materials, it is necessary to consider the characteristics and requirements of the parts, balance the machining accuracy and processing efficiency, consider cost-effectiveness, and comprehensively consider the reputation and after-sales service of the supplier. Only by scientifically and rationally selecting materials and CNC machining service providers can high-quality and efficient production be achieved, and competitiveness and market share can be improved.

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