The simple answer is in most unwind applications either system will work equally well and the brake system will be significantly less expensive and less complicated.
The only advantage a drive system has over a brake system is:
- The drive system can maintain more precise tension during the acceleration of the roll. This is very important if you are running large rolls of very delicate materials (such as tissue paper) or materials that are very extensible.
- A driven unwind can also help with achieving proper registration during acceleration faster than a brake system, although this usually requires servo motors, which can be more complex to install, commission and maintain.
- When you are running at a constant speed and it is acting as a brake it can generate electricity rather than heat. This is only advantageous if you can economically utilize this generated electricity.
The disadvantage to drive system is:
- Significantly more expensive. Not only are the individual components as much as 2-3 times more than a brake system, the installation and service usually requires personnel that are very familiar with drive controllers, PLC, etc.
- Drives and PLCs are constantly changing. As maintenance and service personnel change in your facility, new personnel are often not familiar with the older brands and software versions on the installed system. This will often require calling in service personnel that are very familiar with the drive but may not be familiar with Tension control or your particular application.