Hard or Linear Guideways for Machining Centers?

We often hear that there are two types of guideways in CNC machining centers: hard guideways and linear guideways. So when purchasing a machining center, people often ask: Which is better, hard guideways or linear guideways? What are the differences between them?

What are hard guideways and linear guideways?

• Hard guideways: Hard guideways refer to the guideways that are integrally cast with the machine tool bed. Then, the guideways are machined on the basis of the casting. That is, the shape of the guideway is cast on the bed, and then the guideway is processed through quenching and grinding. There are also cases where the bed and the guideway are not necessarily integrated. For example, in the case of steel - inlaid guideways, they are machined and then nailed to the bed.
• Linear guideways: Linear guideways usually refer to rolling guideways, which are the same type used in the linear modules often seen in the machine tool industry. These components are commonly called "linear guide rails". A linear guide rail consists of two parts: the rail and the slider. There are internally - circulated balls or rollers inside the slider, and the length of the rail can be customized. It is a modular component, a standardized and serialized product produced by specialized manufacturers. It can be installed on a machine tool and replaced after wear. Many machine tools in the field of precision machining mostly use high - precision linear guideways as the machine tool guideways, which greatly ensures the machining accuracy of the machine tool. Well - known imported brands include Rexroth from Germany and THK from Japan, and among domestic ones, Nanjing Machine Tool Accessories Factory, Hanjiang Linear Guideways, and HIWIN from Taiwan are relatively good.

Which is better for a machining center, hard guideways or linear guideways?

In fact, there is no absolute answer to whether hard guideways or linear guideways are better. It only depends on whether they are suitable or not, because their focuses are different. Let's take a look at their respective advantages and disadvantages.

1. Advantages, disadvantages and applications of hard guideways

• Advantages: Hard guideways have a large sliding contact surface, good rigidity, strong anti - vibration ability and high load - bearing capacity, which are suitable for heavy - load cutting.
• Disadvantages: Hard guideways involve dry friction. Due to the large contact surface, the friction resistance is also large, so the moving speed cannot be too fast. At the same time, the creeping phenomenon is likely to occur, and the gap on the moving surface will lead to machining errors. The maintenance of the machine tool guideways is of utmost importance. Once the guideways are not lubricated sufficiently, it will cause the guideways to burn out or excessive wear, which are fatal to the accuracy of the machine tool.
• Applications: Hard guideways are suitable for heavy - cutting operations, large - scale molds, high - hardness workpieces and workpieces with general precision requirements.

2. Advantages, disadvantages and applications of linear guideways

• Advantages: Many modern machine tools can run at extremely high speeds, especially during rapid traverse, which largely depends on linear guideways. Linear guideways can achieve zero clearance between the rails after pre - tightening, with high precision. In terms of service life, linear guideways are much longer than hard guideways.
• Disadvantages: The ability of linear guideways to withstand cutting forces is relatively smaller than that of hard guideways. However, this is only in comparison with hard guideways. In fact, the load - bearing capacity of linear guideways on many modern machine tools has been greatly improved.
• Applications: Linear guideways are suitable for high - speed machine tools and can perform high - speed cutting. They are suitable for processing products and small - sized precision molds. Nowadays, more precision machining centers use linear guideways.