CNC machine tool line rail, hard rail, who is better?
We often hear linear and hard rail machining center machines. What is the difference between them? Which one is better to use? I believe many people in the industry do not know. Today we will introduce in detail what is a hard rail machining center machine and what is it? Line rail machining center, where is the difference between the two, which is better to use.
Linear rail machining center
The full name is the linear guide machining center machine, generally refers to the rolling guide. There are two common structures: ball guides and roller guides. The difference is that the ball guide is a point contact type, and the roller guide is a line contact type. The principles are the same, and they all roll on the guide to drive the slide.
1. The linear guide is supported by rolling parts, and its rolling and sliding performance is better than that of the hard rail.
2. Due to its small friction coefficient, the moving speed is fast;
3. Similarly, the friction coefficient is small, so the wear is small;
4. Generally, linear guides are made of better materials and more precise equipment, so their accuracy is also higher;
5. Convenient maintenance in the later stage. After the guide rail is worn, the line rail is easy to replace, and the hard rail is more troublesome because the gap needs to be adjusted.
Disadvantage: Because of its smaller contact surface, its rigidity is lower than that of the hard rail.
Hard rail machining center
Generally refers to the integrated casting of the guide rail and the bed, and the material row number is generally not lower than HT250, and the Brinell hardness of the body is between HB180-HB240. After the rail part is quenched by high frequency or super audio, the hardness is generally above HRC50 °, which makes it have excellent wear resistance (steel-mounted rail is also a kind of hard rail). The hard rails used by CNC machining center machines are generally rectangular structures, commonly known as rectangular guides.
Advantages: The large sliding contact surface of the hard rail makes the machine tool rigid and stable.
Disadvantages: Due to the large contact surface, the friction resistance is also large, the wear is fast, the movement speed is limited, and defects such as crawling are prone to occur. Therefore, most machining center machine manufacturers use the guide rail paste process to reduce hard rail wear and crawl defects.
Which is better for a linear or hard rail machining center?
The linear rail has high speed and high precision, suitable for high-speed machines, high-speed cutting, and suitable for processing small precision molds. The rails are pre-tensioned to achieve zero gaps between the rails. Hard rails are dry friction, with large load and high strength, suitable for heavy cutting. Hard rail movement requires movement on the moving surface with clearance, and the friction coefficient is large, which is prone to adhesion and processing errors. It is mostly used under heavy load. Suitable for machining workpieces with high hardness and low accuracy requirements.
In fact, there is nothing good or bad about hard rails and line rails, only whether they are suitable. Because their processing focuses are different, the linear rail machining center machine is biased towards workpieces with low hardness and high precision, while the hard rail machining center machine focuses on workpieces with low hardness and high precision requirements.