CNC operators know that their machines are only as good as the power delivered to them, and this power comes from the spindle drive. However, there is confusion as to what constitutes a spindle drive. It’s more accurate to look at it as the spindle drive system.

High-frequency spindles turn at up to 250,000 RPM, and this is because of advancements in spindle drive systems. Part of the system is the electric motor. The motor is an internal component of the spindle, or sometimes connected by a belt or other mechanism, and spins the shaft and the connected tool. An interface, incorporating a variable frequency drive, allows the operator to provide instructions—specifically, how fast the spindle should turn and at what angle, to achieve the desired high-speed grinding process. This can include drilling, tapping, cutting, or any other process that involves high speed rotation. The final part of the system is the encoder, which sends information back to the interface, reporting on the speed of the spindle and the rotational position. The data from the encoder tells the interface that the spindle motor interpreted and carried out the directions correctly. The interaction between these three components comprises the spindle drive system. 

Call GMN USA today to learn more about spindle drive systems.

Today’s manufacturing environment—including aerospace, defense, automotive, medical device manufacturing, and others—uses harder metals or other specialized materials machined to close tolerances and with intricate detail. In the case of medical devices, these machined parts sometimes make the difference between walking unhindered or using a cane, and sometimes even life and death. High-speed drives make this possible, allowing instant user input and providing immediate feedback. High-speed drives also mean increased torque for heavier cuts and doing so without losing speed or precision.

The ability to produce more quality parts in a shorter time means that manufacturers can fill an order or finish a project and move on to the next one. They can accomplish more with the same amount of personnel.

As we said earlier, three different components comprise the spindle drive system. Put these three components together and you can create a spindle-drive system that can generate 200 horsepower (150 kW).

When evaluating spindle motors, there are several considerations:

• High power density. What is the power generated by the motor? When comparing two motors with similar power densities, the smaller of the two is generally the best choice because it’s more efficient.
• Appearance. Don’t confuse this term. You’re not running a beauty pageant for electric motors. Look for compactness, robust construction, and precision design. In short, the motor should look like it was designed on a high-speed spindle.
• Balance. Weight should be evenly distributed in the motor, especially the rotor and shaft. Good balance means less noise, less vibration, and cleaner cuts. Poorly balanced motors mean more vibration and difficulty achieving intricate tolerances and finishes in the workpiece.

The interface is the heart of the spindle drive system. All things being equal, the more features, the better. Some things you should consider in selecting an interface include:

• Flexibility. Interfaces should be able to direct constant speed or variable RPMs and be capable of directing the motor to apply a specific amount of torque, depending on the project.
• Compatibility. Interfaces should be compatible with most motors and spindle brands, including high-frequency spindles. They should work with almost any application.
• User Friendly. The interface should be easy for the spindle operator to enter project information and specifications.
• Modern Technology. CNC spindles are like many other components in that they are constantly changing with new technology. Look for prioritized waveform quality, low-speed and high-speed motor optimization, and robust software.

As mentioned earlier, the encoder is a sensor or set of sensors that report to the interface, confirming that its instructions were carried out. A discrepancy in this data will sometimes halt the process until the operator corrects the problem. 

• Rotation and speed sensing. Precise angles and pinpoint speeds ensure the accuracy of each part.
• Closed-loop control and error compensation. Some systems don’t stop the CNC process. They can detect a change, such as a worn tool or a change in the raw material, and automatically make error corrections.

When assembling a spindle drive system, it’s advisable to source the electric motor, the interface, and the encoder from the same vendor. This allows you to ensure that you purchase compatible components. Also, verify that the spindle drive system is compatible with the spindle itself. If components are mismatched, you risk less than optimum spindle performance. Worse yet, the mismatch could cause damage to components. Rely on your vendor for accurate information regarding matching the spindle with a spindle drive system.

Call GMN USA today to ensure you correctly match the components of your spindle drive system.

What’s the advantage of pairing the spindle, motor, and interface to the type of work your machine shop does? Here are the most significant benefits:

Time is money, especially with expensive machinery such as these components. Increased productivity means your factory can produce more. When spindle components are not optimized, production slows. Employees are frustrated, customers are impatient, and your reputation for on-time delivery suffers.

Nothing is more satisfying than powering up your spindle and having everything work right the first time. Quality parts that communicate project parameters help avoid unscheduled downtime, which is costly and frustrating.

There is little room for error in today’s CNC workplace. Parts have to work the first time. Cut lines must be clean, holes must be precise, and finishes must be free of chatter and blemishes. A quality, well-matched spindle drive system ensures your reject box is empty.

Spindles turn at incredibly high speeds. A mishap can send a broken tool bit rocketing inside a machine enclosure or, worse yet, across a factory floor. Properly equipped, a quality spindle drive system protects employees from injury.

Well-matched, quality parts work well together and also treat each other well. You will get more life out of your CNC spindle system and experience fewer repair headaches.

You can purchase the best components and ensure they are well-paired, but the final step to long-lasting spindle drive system performance is proper maintenance.

The operator should examine the entire spindle assembly at the start of the shift, the end of the shift, and several times a day. Look for loose or worn components, excess debris, discarded tools, parts of workpieces, or anything else that’s out of place. Whenever the operator is away from the spindle, they should check it before starting again upon return.  

Again, remove excess debris, lubrications, or leftover coolant. Spindles need airflow, as do the drive systems, so don’t allow boxes of raw materials or finished products to pile up in the spindle work area. Design your workflow so your spindle assembly, including the motor and the interface, is free from clutter.

Overheating is a major concern with high-speed drives. Make sure your coolant system is functioning well. If you use a chiller, check it regularly, too as it’s an important part of the spindle system.

Ensure the lubricator is set up and functioning according to factory specifications, using OEM-recommended lubricants. For permanent grease spindles, follow the run-up procedures if the spindle has been unused for an extended period.

Your spindle and spindle drive system has a sound. It shouldn’t be much, depending on the work material, but there will be a sound you become used to. Any deviation in that sound is an indicator of a potential problem. Pay attention to bearing fault frequencies, too, as they are often precursors to a failing spindle.

Check all connections between the interface, the electric motor, and the encoder. Wires may become nicked or frayed by tools or products during removal. Check all connections for corrosion or contamination from lubricant or coolant. If you find anything, clean it or repair it immediately.

Loose or improperly mounted tools cause problems. They either break or cause balance issues. Pay careful attention when changing tools or when the spindle assembly features an automatic tool changer.

The key to assembling a high-performing spindle drive system that is compatible with the rest of your spindle assembly is having a partner you can rely on for technical information, advice, and top-quality components. GMN USA is that partner. With over 100 years of CNC spindle experience, our team offers a robust range of products, including high-speed electric motors, manual and automatic tool change spindles, drives, lubricators, and more to elevate your operations. 

Call GMN USA today to learn about our selection of spindle drive components.