When the Lights Go Down in the City

Any time we lose power at my house the first thing I think about is that classic Journey song, “Lights (Go Down in the City).” In my head I hear the first line of the song playing. In today’s business world, reliable power is more important than ever because even a brief interruption can mean loss of product, time and revenue. In machine shops, a power outage can be annoying and expensive due to interrupted productivity. When this occurs it’s key to recover your machine tool properly, which can drastically reduce your losses. Many recovers can be as simple as powering back up while other recovers may be a bit more involved.

HOW TO POWER BACK UP WITHOUT INCIDENT

The following steps will help you successfully assess a machine tool and bring it back online without incident:

1.  Power down completely. Even though power was lost, and the machine is only on at the breaker, turn the breaker off and let the machine sit for a minute or two. This will discharge all the drives and power supply, as well as remove some alarms depending on the duration of the power outage.
2. Take a walk. Walk around the machine and check on its physical condition. Is the tool changer halfway through a cycle? Is the tool tip inside a part? All these things can help determine what needs to be done once the machine tool has regained power.
3. Form a plan. If the tool changer is stuck, or the tool is inside the part, review what procedure you will follow (follow the Maintenance Manual recovery guide for the tool changer). If the tool tip is inside the part, review if the part or tool can be removed from the machine without power or will an axis that needs to be pulse handled around after starting up.
4. Verify power. After the power loss you may experience problems with the supply voltage to the machine, including a blown buss fuse. Have the power verified on all 3 incoming power legs to the machine. If one is lost it could single phase a motor causing damage.
5. Remove problems. If parts need to be removed or work holding do so now before power is restored.
6. Power up. Turn the breaker on and power up the machine. With the current Okuma controls there is a UPS power supply and battery to ensure the machine shuts down properly even if power is lost. Once power is restored the control should power up, but there could be alarms related to the tool changer or axis overload. Each individual alarm needs to be reviewed in the Alarm Manual to understand any issues.
7. Recovery. Now that the machine is powered up, it’s time perform any needed tool changer recovery or move any axis away from the spindle and tool tip.
8. Completion. Jog the machine around then check other functions such as coolant pumps and chip conveyors. If you have other peripheral equipment such as bar feeders or unloaders, you will want to check and restart them as well.

When the lights come back on, hopefully no damage was done, or the damage was limited to a part being scrapped. If the machine won’t power on, the tool changer is stuck in an unusual way, or you have alarms that have not been addressed properly. Always remember that Okuma and our distributor network will be standing by ready to help you recover safely and quickly.

About Chris Heeg

Chris Heeg is Board Repair Supervisor for Okuma America Corporation, a world-leading builder of CNC (Computer Numeric Control) machine tools founded in 1898 in Nagoya, Japan. Okuma is the industry’s only single-source provider, with the CNC machine, drive, motors, encoders, and spindle all manufactured by Okuma. The company also designs their own CNC controls to integrate seamlessly with each machine tool’s functionality.

Company: Okuma America Corporation
Website: www.okuma.com
Connect with Chris on LinkedIn.