In the field of high-precision manufacturing, the stability and sealing performance of spindles directly affect the accuracy and service life of industrial equipment. As a world-leading manufacturer specialized in precision bearings and sealing solutions, German GMN has developed the CF non-contact labyrinth seal. With innovative structural design, this product has become a benchmark sealing component for high-speed spindles. It effectively solves common drawbacks of traditional seals including friction, temperature rise and short service life, and is widely adopted in precision machine tools, aerospace equipment, high-speed motor spindles and other high-end industrial applications.

The GMN CF seal is an upgraded version of labyrinth seal technology. Its core design allows direct mounting next to bearings, so no extra space needs to be reserved on the spindle, which greatly optimizes the layout of axial space. The seal is assembled by an inner ring and outer ring made of steel, connected with a retaining ring to form a five-stage labyrinth structure. The axial gap is set to 0.25mm, which creates capillary effect to block liquid penetration and provide reliable shielding. The radial gap measures 0.5mm, and centrifugal force generated during operation builds up backflow to expel contaminants outwards. Equipped with end collecting grooves, the seal can reach full splash-proof efficiency whether the spindle is static or running, preventing cutting fluid and coolant from flowing into the bearing unit.

Different from contact seals such as oil seals and GMN’s own L and M type labyrinth seals, the CF series owns many outstanding advantages. Since there is no physical contact between the seal and rotating shaft, no friction loss or extra heat will be produced during operation, making it perfectly suitable for long-term high-speed running conditions. Without wearable parts inside, the seal can work for an extremely long time as long as hard particles like metal chips and dust are kept away, which helps enterprises cut down maintenance costs largely. Its designed speed rating is higher than that of matching high-precision bearings, so it can adapt to spindles working at tens of thousands of revolutions per minute without failure risks under high speed.

There are totally 37 standard specifications for GMN CF seals. All models feature a uniform width of 6mm and 1mm axial gap, with dimensions precisely matched to standard bearings for easy selection. The product line is divided into three categories to meet diverse installation and working requirements.



 

The following table lists parameters of mainstream models, covering most common bore sizes and compatible bearing types.


 

The naming rule of this product is easy to understand. Take CF 6204 A0 as an example, CF stands for non-contact labyrinth seal series. The number 6204 refers to the matched bearing model, which is the 6204 angular contact ball bearing. A0 and S10 are structural marks, A0 represents standard series while S10 stands for compact series.

Two material options are available for GMN CF seals to fit different load and temperature environments. Nitrided steel is the standard material with hardness over HRC 45, it can transmit bearing preload force and works well under heavy load, with operating temperature ranging from -40°C to 170°C. Aluminum alloy is applied for high temperature working situations, this lightweight material has good thermal conductivity and can endure temperature from -40°C to 200°C up to 200°C. Strict production standards ensure reliable performance, the flatness of surface is controlled within 5μm to keep even sealing gap all the time. The 0.5mm radial gap balances sealing effect and installation tolerance. The seal can fully resist liquid splash under both static and running status, even when facing continuous flushing of large flow coolant.

Installation of GMN CF seals is simple and convenient, no modification on original spindle structure is needed. The seal is installed between bearing and shaft nut, the whole process only needs a small air cylinder to push and fix the part. It can also be retrofitted on old spindles quickly, reducing equipment downtime effectively. What’s more, the preload of bearings will not be affected, for the seal can share and transfer load normally, which fully satisfies the assembly demands of high-precision spindles.

This series of seals can be used in a wide range of industrial equipment. In precision machining industry, it is installed on high-speed machining centers, CNC lathes and grinding machine spindles to protect bearings from coolant and cutting fluid. For high-speed motor spindles running at extreme RPM, the zero heat generation and long service life make it a ideal choice for non-stop mass production. In aerospace field, the lightweight aluminum version is widely used on high-precision rotating components, its stable performance can handle extreme temperature conditions. For mold and automobile manufacturing, the seal prevents dust and oil contamination on high-speed stamping equipment and precision mold spindles, greatly extending the overall service life of mechanical parts.

As one of the core labyrinth seal products from GMN, CF series has obvious improvements in structure and performance compared with traditional L and M type seals.