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How to use collet to better keep the knife holder tight?

2020-05-22 02:05

How to use collet to better keep the knife holder tight?

The selection of collet needs to be based on appropriate performance indicators and application scenarios, and the subsequent use process still needs to pay attention to. The maintenance cost of the collet in production requires thousands of dollars, but the result of neglecting the problem may be a greater loss. Spindle wear, loss caused by downtime, and collisions caused by tool pulling on the spindle may cause manufacturers to lose more than tens of thousands of RMB.

The tool directly acts on the parts to be processed, and the machining accuracy of the tool will directly affect the quality of the workpiece. As the technological requirements of the product increase, the accuracy of the tool processing is further improved, and the requirements for tool clamping are also higher.

In the processing, the tool chuck grips the tool shank differently, and it can be generally divided into three types: screw side fixing type, spring bushing type, and hydraulic type. The screw-side chuck is mainly used for the clamping of end mills and other tools, and the coaxial is the worst; the spring chuck is widely used for hole processing tools such as taps, drills, and even reamers; the accuracy of hydraulic tool chuck It has the highest performance index in all aspects, but its structure is complex and the price is also the most expensive. It is mainly used for reaming and drilling and milling with special requirements.

Other potential problems caused by insufficient support of collet are not necessarily serious, but the cost is still high. Problems such as vibration and noise, repeatability and reduced tool life or reduced surface smoothness may be caused by the spindle's weak support to the tool holder. Generally, similar problems are encountered in the processing workshop, and a simple tool is used to check the chucking force. Many companies also provide this tool to detect the support force of the chuck.

Collet's inspection work needs to be carried out frequently to ensure that the company is aware of its downward trend before problems occur.

So how to use collet to better keep the knife holder tight? LONNZ shares the following reference measures to keep the knife holder tight:

1. Inspection frequency: It is recommended to check the support of collet every two months.

2. How long does the collet usually perform maintenance: about 2 to 5 years. The service life is related to many variables, including the needs of the cutting application and the time of tool changeover.

3. Appropriate supporting force: The optimal supporting force of collet is different, even between similar devices. According to the product data provided by the manufacturer, you can grasp the appropriate pressure.

Generally speaking, the pressure of the spindle taper 40 is generally 1800 ~ 2500 lb, the pressure of the spindle taper 50 is generally between 3800 ~ 4800 lb, and some equipment with a taper 50 requires 9000 lb or more. The HSK system is different. A spindle with a similar taper requires twice the force. Because the HSK system requires a greater chuck force for proper engagement of the tool holder and the spindle surface, this equipment requires more frequent inspections.

4. Maintenance of collet: The main shaft must not have excessive support force, otherwise the bearing may be overloaded, so the ideal value cannot drop much. When the support force drops below 90% of the manufacturer's recommended value, maintenance should be considered.

Abrasion is another reason for the reduction of the collet's support force. Vibration, friction, and bacteria in the coolant can cause frictional corrosion. Some mechanics use an abrasive cloth to remove them by hand. This treatment method has some problems because each time it will grind a part of the material from the shaft cone, which will reduce the accuracy and the error of large diameter parts will be relatively large. And during heavy cutting, the smaller tool holder is more likely to move out of position. Due to the capillary phenomenon, more metal particles may remain between the spindle cone and the tool holder. The result of this is greater wear.

The contamination on the tool holder indicates that the collet no longer supports the tool holder tightly. The damage of the tool holder is related to the damage inside the spindle. The damage is not limited to the tool holder, but may also be caused inside the spindle. This invisible damage is also a hazard caused by insufficient support of the chuck. The maintenance collet maintains the proper chuck force to ensure that the knife holder never moves.

High precision spring collet and tool holder

High precision spring collet and tool holder