Should you let your CNC run overnight? The truth is, lights-out machining can drastically increase productivity and profitability if done correctly. Running your equipment unattended is fairly common at many successful machine shops these days. However, it does require specialized equipment, planning, processes and safety precautions.
Advances in CNC controls, automation technology, tool monitoring and robotics have completely changed the manufacturing landscape. Many shops are looking for ways to boost productivity without increasing labor costs. One popular option is leaving CNC equipment running unattended overnight, on weekends, or in the evenings.
What Is Lights-Out Machining?
Lights-out machining is the practice of running CNC machinery with minimal or no supervision for extended periods. The term comes from the early concept of shutting off the lights and letting your equipment continue making parts all night long.
Rather than having operators standing by and manually loading parts, tools and overseeing production cycles, automated equipment does the work. When properly set up, machines will continue producing parts while employees are away from the shop floor.
Lights-out machining can be as simple as one CNC machine making a part all night or as complex as fully automated cells with robotics, pallet changers and tool monitoring software.
Why Would Shops Leave Their CNC Machines Running Overnight?
To put it simply, unattended machinery is more productive. CNC machines are expensive. Every hour a machine sits idle is lost production.
When equipment runs only during an eight-hour shift, it typically isn’t used for more than half the day. By allowing production to take place overnight and on weekends, manufacturers can significantly increase machine utilization.
Common benefits include:
- Increased production without buying new equipment
- Reduced labor costs per piece
- Decreased turnaround time on orders
- Improved return on equipment purchases
- Competitive advantage over other machine shops
Lights-out machining can effectively double or triple the productive hours your equipment generates.
Is Lights-Out Machining Safe?
Yes and no. Lights-out machining can be performed safely, but shop owners should never underestimate the risks.
There is always risk involved with leaving a machine unattended. If something goes wrong, there will be no employee on site to stop the machine immediately. Tool breakage, material flaws, coolant problems or programming errors can turn into expensive issues if they go unnoticed.
Successful shops have multiple safeguards in place to prevent losses. Machine monitoring software, tool life management, sensors, alarms and remote smartphone alerts are all common safety measures.
Safety should always come first when running equipment after hours.
Which Parts Should I Run Overnight?
Just because you can leave your CNC machine unattended overnight doesn’t mean you should. Certain jobs are better suited for lights-out machining than others.
Generally speaking, the best overnight jobs are stable and predictable processes with a proven track record. If a part runs smoothly on attended shifts, there is a better chance it will continue running overnight. Some of the best candidates for unattended machining include:
- Repeat production jobs
- Parts that do not require frequent tool changes
- Jobs that have very little cycle-to-cycle variation
- Parts made from material with little variance
- Processes with low scrap rates
Prototype parts, odd materials, and jobs that require frequent operator intervention are usually not ideal for lights-out machining.
What Are the Risks of Running My CNC Machine Overnight?
Of course, there are risks associated with leaving your equipment unattended. While the benefits can be great, there is always the potential for costly mistakes or losses.
Tooling problems are a big concern. One broken cutter can ruin a part and possibly damage the fixture or machine if left undetected.
Programming errors can also be costly with overnight production. What may only take thirty minutes to fix during a supervised shift could result in dozens of scrapped parts if they continue to run overnight.
Other issues could include coolant failures, chip build-up, power outages, material problems or workholding issues.
Without proper detection and monitoring, small problems could turn into big losses before you even know they exist.
How Important Is Tool Monitoring?
Tool monitoring is critical to successful lights-out machining. A worn or broken tool can ruin part quality and possibly damage your CNC machine.
Many advanced CNC control packages offer tool monitoring that can detect impending tool problems by monitoring spindle load, cutting forces, vibration and more.
Some shops even use automated tool measurement systems that verify tool dimensions before a tool is put into production. Others have strict tool life management policies that prevent tools from reaching the failure point.
The more you can control and monitor your tooling process, the more predictable your overnight production will be.
Can Automation Help with Overnight Production?
In most cases, automation is the key to successful lights-out machining. Automated bar feeders, pallet changers, robotic part loading and automated workholding solutions can minimize the need for human intervention.
Automation also eliminates many of the human errors associated with manual loading and unloading.
As automation technology becomes more affordable, smaller machine shops are implementing unattended machining strategies.
How Do I Monitor Machines After Hours?
Technological advances have made it much easier to monitor equipment after hours or while everyone is away on vacation. Many CNC controls will now allow you to send alerts straight to your cell phone, tablet or computer.
These alerts can notify you of machine stoppages, tool breakage, spindle overload alarms or even let you know when production is complete. There are also remote monitoring systems that allow you to view machine status live without even being at the shop.
Remote monitoring and alerts can provide peace of mind while also allowing you to react quickly if there are any issues.
What Should I Check Before Running My Machine Overnight?
As with any process change, you should verify your shop is set up for success before attempting lights-out machining. There are several areas you should look at to ensure supporting components will not fail.
Verify that coolant levels will not go below recommended levels. Are your chip detectors working properly? Are air compressors, oil filters and lubrication systems clean and ready for extended use?
Preventative maintenance becomes even more crucial when your equipment is running for longer periods of time. A machine that runs perfectly fine during normal shop conditions should have a much higher success rate when left unattended.
Is Lights-Out Machining Worthwhile for Small Shops?
A lot of people think you need to have tons of equipment before leaving your machines overnight is an option. However, that is not the case at all.
Small machine shops can see a huge productivity increase by simply allowing one CNC machine to run overnight with a well-thought-out automation plan. Simple additions like bar feeders, pallet systems, and remote monitoring can create windows for unattended machining.
Start with something you know will work and slowly expand your automation as you gain confidence in your ability to leave machines running unattended.
Many shops try running short periods of time unattended before trying full overnight cycles.
What is the Truth About Lights-Out Machining?
The truth is, lights-out machining can be extremely profitable for your shop. Manufacturers that invest in reliable equipment, automation, tool monitoring and set processes can gain a huge productivity edge over their competition.
Just because your equipment can run overnight doesn’t mean you should fire it up and go home. Lights-out machining takes preparation, proven processes, preventive maintenance and risk mitigation.
When done correctly, overnight machining can allow you to boost production, lower costs, and maximize the return on your CNC equipment investments. If you’re looking for a way to gain an edge over the competition in this tough economy, running your CNC equipment overnight may be one of the best options.
Whether you are just starting your first foray into automation or looking to enhance an existing automated cell, understanding whether you should let your CNC run overnight is important. The truth about lights-out machining can help you make better decisions that improve efficiency, profit margins and long-term shop productivity.
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