Light it up

Modern machine tools are impressive beasts, capable of incredible feats. However, one basic aspect of machine operation is consistently overlooked in favor of machine efficiency: the way the operation appears to the naked eye.

“What we are seeing is that many CNC machines are coming in from factories overseas with very poor-quality lighting,” said Richard May Jr., industrial sales manager for task lighting manufacturer O.C. White Co., Thorndike, Mass. “You’d think such a rudimentary aspect wouldn’t be overlooked, but the builders are so concerned with dwell time, cycle time and machining parameters that they’re not really taking the actual operator who will be using the machine into account. Lighting plays a huge role in not only operator safety, but also in productivity.”

O.C. White’s Green-Lite High Intensity LED Linear machine light features a die-cast aluminum body to direct heat away from the electronic components, as well as tempered safety glass and a nickel-plated bezel. Image courtesy O.C. White.

O.C. White’s first fixtures were kerosene-based when it began in 1883. Since then, the company has evolved with the technology, going from oil to electric incandescent lighting to fluorescent and halogen lamps. Although lighting options are better than ever, builders still frequently ship machine tools with outdated lighting technology.

“Each new development presents a large technological jump, which is frequently overlooked by the consumer, who likely thinks ‘light is light,’” May said. “But not all lighting is created equal; it’s the practical and specific application of light in order to get a job done that matters. High-quality lighting fixtures not only provide the precision application of light that the customer demands, but also the quality to stand up to the harsh conditions in the modern CNC machine.”

Bright Choice

While incandescent, fluorescent and halogen lamps are familiar technologies, LED lighting is dramatically changing the industrial lighting marketplace, according to Louis Calvo, director of sales and marketing for Waldmann Lighting, Wheeling, Ill. He said Waldmann converts fluorescent and halogen machine task lights to LED.

“What we’re doing is switching people from a fluorescent or halogen source, which might last from 1,000 to 5,000 hours of operation, and getting them a source that will give 50,000 hours of operation,” he said. “The only reason to use incandescent, fluorescent or halogen lights is if you’re looking to source the lowest-cost alternative. That’s not to say that those products don’t have a place—there is still a very strong market in residential—but, essentially, the benefits of switching to LED lighting can be summed up as ‘everything but cost.’ That cost can be a barrier to entry for some, but it is coming down as the volume of LEDs being produced increases.”

That up-front cost, according to Ron Roehl, president of robotics and engineering provider CNC Solutions LLC, Johnson Creek, Wis., can be from one-and-a-half to three times the cost of a comparable lamp-driven light source, but companies that get past the sticker shock will see many benefits.

“Let’s look at a machine that’s running around the clock,” he said. “If a lamp burns out, you have to shut the machine down, hire an electrician who has to pull the light out, disassemble the enclosure while, hopefully, not compromising the integrity of the waterproofing, put a new bulb in, then reverse the process. Between the cost of the bulb and the cost of all that downtime, how much money are you really saving? The cost of changing two bulbs is going to add up to the difference in the price of buying the LED in the first place.”

Machine tool lights, such as the Mach LED Plus from Waldmann, must be totally waterproof to protect the electronic components from conditions inside a CNC machine tool. Image courtesy Waldmann Lighting.

Calvo agreed, noting an LED’s significantly longer life. “You actually wind up paying far more for the fluorescent fixture over time, without even taking the electricity consumption or procurement costs into account,” he said.

In addition, LEDs provide a different type of light, noted O.C. White’s May. While traditional, lamp-based light sources are essentially floodlights, in that they provide a 360° field of illumination, LEDs are spotlights. However, all LEDs are not created equal.

"Low-quality LED lighting fixtures sold today still employ LED technology from the 1970s, and the light output and quality show it,” May said. “Time is money in today’s machining industry. High-quality LED lighting will not only shorten your tool setup time, but also minimize scrap, as you can identify problems more quickly while watching the machine run.”

O.C. White only currently manufactures LED lighting, May said, although the company offers some legacy products, such as gooseneck and rigid-arm incandescent lights for long-term customers. He estimated that 95 percent of the company’s sales are LEDs and predicted those LEDs will be hopelessly outdated in fairly short order.

“The efficiency jumps that have been achieved in LEDs are phenomenal,” May said. “If you look back 10 years to what an LED was, you wouldn’t believe the difference today. One of the most cutting-edge products coming are OLEDs, or organic LEDs, and they’re unlike anything on the market today. There are prototype lighting arrays the size and thickness of a sheet of standard printer paper. The idea of what a light fixture needs to look like will be turned on its head with this new technology. It is a great time to be designing quality LED products.”

Electric Slide

Electricity consumption is another major factor when choosing lighting, and a huge benefit of solid-state lighting is efficiency.

“The actual conversion of electricity to visible light is wildly different when you’re talking about LEDs,” May said. “Halogen, incandescent, fluorescent—they all range from 15 to 45 lumens per watt. The LEDs we use in our fixtures average 118 lumens per watt, which means we get substantially more light from substantially less energy.”

While other lights utilize 110v to 277v AC power, LEDs run on 24v DC power. This means, unless a shop or CNC machine already has a 24v DC power supply available, the LED lighting fixture will need a driver to step down the voltage from the power source. In addition to the power savings, lower voltage reduces safety concerns, as operators who come in contact with live electrical components would be exposed to considerably lower voltage.

And that’s not the only safety benefit, according to Waldmann’s Calvo. “Fluorescent operates at 50 to 60 Hz, and one thing you hear from folks working under fluorescent lights all day is complaints of headaches and eye strain,” he said. “An LED cycles at 300 MHz, which is invisible to the human eye. It’s cycling so fast you don’t have the flicker effect you get with fluorescent light.”

This is significant, he continued, because the slower cycling can produce a stroboscopic effect, in which the flickering of the light coincides with the rate of motion of an object, such as a spindle.

“If the cutting tool and the light are flickering at the same rate, it will actually appear as if the spindle is not moving,” he noted. “That means you could have an injury from someone reaching into the machine, thinking the tool is not moving, when in reality it’s just an optical illusion.” While this concern typically only exists on very old machines, because newer ones have an array of safeguards to prevent these types of accidents, the bottom line is that LEDs provide a more consistent light level during operation, eliminating the possibility of any stroboscopic effect taking place.

Close It Up

While LEDs are the new standard, one thing all machine tool lights have in common is the importance of a proper enclosure. After all, the lights are inside a machine tool and subject to flying chips, flood coolant and even chunks of debris. The enclosure must be rated to resist water as well as debris at a rating of IP67.

“IP67 is an IEC [International Electrical Congress] rating for dust and water, and is about the highest you can get for immersion and spray-down in machining environments,” said CNC Solutions’ Roehl.

Enclosures for lamp lights are made of clear acrylic or borosilicate glass, he continued, with the clear plastic acrylic being the more inexpensive and less resilient of the two.

Waldmann’s Lumatris line utilizes high-output LEDs with specially designed optics to direct light where it is most needed, while minimizing glare and outward heat. Image courtesy Waldmann.

“When chips hit the surface of the acrylic lens, they’ll abrade that lens to the point that visibility is basically lost,” he said. “Borosilicate glass is a heavy glass resistant to abrasion and impact, and probably over 99 percent of lights we sell are borosilicate-glass-enclosed.”

But simply upgrading to borosilicate glass won’t totally solve vision problems, Waldmann’s Calvo noted.

“Halogen lamps burn extremely hot,” he said, “so hot that the glass on the front of the lamp actually burns the cutting fluid onto the lamp, which creates a film that very rapidly degrades the output of the light.”

Waldmann’s entry to the world of LEDs, a product called SpotLED, addresses this problem because the heat generated by LEDs is primarily in the drivers, which are in the back of the fixture. LED fixtures can utilize an aluminum heat sink to pull heat from the electronic components, and the borosilicate glass stays relatively cool.

Lighting is an important, overlooked facet of machine tool building, and while builders may not be inherently aware of this yet, there’s no reason for shop owners to remain in the dark.

While the majority of machine tool lights are LED, the low up-front cost of fluorescent light fixtures still have a niche in the market. Image courtesy CNC Solutions.

“What we deal with is an underappreciated and, frankly, underrepresented piece of a manufacturing environment,” O.C. White’s May said. “Think of how many CNC machines there are running in this country. For every operator who’s happy with the lighting in their machine, there are 15 other operators grumbling with a flashlight in their back pocket, wishing for something better. LED lighting is one of the best investments that any manufacturer can make to improve not only productivity, but employee morale.” CTE

About the Author: Evan Jones Thorne is assistant editor for CTE. Contact him at ejonesthorne@jwr.com or (847) 714-0182.