Adopt new directions in industrial lighting

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By John L. Fetters, CEM, CLEP

PlantServices.com

Keywords: "lighting" and "efficiency"

As the industrial sector continues its transition to a 21st century digital age, many issues affect production facilities and their lighting systems. Find out what they are and how your plant can benefit by changing.

Business in the U.S. has changed dramatically from the days of heavy industry when illuminating with high-pressure sodium systems was common. Those who specify and buy lighting systems for industry should be aware of the current trends in manufacturing.

As the industrial sector continues its transition to a 21st century digital age, many issues affect production facilities and their lighting systems. An aging workforce, worker productivity, product quality and technological advancements, such as miniaturization, affect the way effective manufacturing facilities are lighted.

Providing an effective lighting design for a manufacturing facility is a challenging task. Industrial lighting systems should provide energy-effective illumination in quantities sufficient for doing productive work safely and with quality to enhance visibility and productivity in a pleasant workplace. The goal is a reliable and efficient system that is easy to maintain. The tangible benefits of reduced energy costs resulting from improved efficiency are easy to calculate but, for many companies, there need to be additional compelling reasons for investing in a new lighting system.

Poorly designed lighting systems, on the other hand, have been shown to reduce worker productivity, increase absenteeism and decrease safety. Downtime is sometimes used as an indicator of work quantity and errors; scrap or rework can be used as an indicator of work quality.

The soft benefits

Many facilities have engaged in the International Organization for Standards ISO 9000 certification, the most widely known and successful manufacturing quality standard. The program addresses lighting in the section that ties good lighting to high product quality.

Other benefits of well designed industrial lighting include reduced eye fatigue and headaches, which keeps workers alert and on the job. These lighting systems provide the right amount of light for the occupants to work productively.

Improved workplace appearance through better lighting can increase worker morale, improve the company image and reduce accidents. These intangible benefits are more difficult to measure, but they can far outweigh the other benefits.

The always demanding manufacturing processes require lighting systems to support a wide variety of visual tasks — from highly controlled, precision clean rooms to uncontrolled, less-than-sterile foundries. Many older industrial lighting systems are merely “laid out” to provide a certain light level on a horizontal work plane. Inadequate lighting often is the result of using only an overhead system to light many vertical tasks found in most manufacturing facilities.

Using lighting design software to render light patterns can help you model the lighting on vertical work surfaces. This approach represents a departure from the traditional method of simply looking up a recommended (horizontal) light level for a certain task in a particular industry. Because many tasks are common across industries, “The 9th Edition of the Illuminating Engineering Society of North America (IESNA) Handbook” changed directions and now concentrates on visual tasks and the quality requirements for each. Better industrial lighting should be the result.

Using high tech

An engineered approach to illuminating your manufacturing tasks starts with the task’s visual requirements and an ambient system that might be able to use daylight, high-intensity discharge (HID) or high-intensity fluorescent (HIF) systems supplemented with task lighting. Manufacturing tasks have changed, especially in their orientation. Many tasks must be viewed on the vertical plane, whereas traditional tasks were on the horizontal plane. This change in viewing orientation requires less straight-down light and more light on the vertical plane coming from different directions, including light reflected from the ceiling. Industrial lighting applications require designers to understand the tasks to be performed, which determines the right type of lighting.

The robots and automatic machines doing so many repetitive tasks in modern factories don’t need to see, but the maintenance personnel who care for them do. This represents an opportunity to control the lighting. For example, a low lighting level can be provided when the machines don’t need tending and a high level provided when machinery requires attention. In addition, automated machinery might be on tour stops, and warrant illumination so guests can observe the fascinating operations.

Most industrial tasks now require better color rendering than traditional tasks. This can easily be provided using lamps that have a higher color rendering index (CRI). Most new plant fluorescent lighting  systems use lamps that are rated at 85 CRI. Another benefit of using higher CRI lamps is that they provide better contrast for black and white tasks.

To improve contrast, consider using task lighting from the proper direction to evaluate the visual results. The IESNA RP-7 (Recommended Practice for Industrial Lighting) shows how to light various piece parts and products and shows photos of these effects. Contrast can be further improved by using a contrasting colored background. The result is similar to the effect when white pearls are displayed against a black velvet background. The size and the shape of the pearls are easily seen and any surface blemishes are easily detected.

The quality angle

It can be challenging for an inspector to locate defects on product surfaces that are sometimes reflecting light back in their eyes. When task lighting flickers, inspectors have difficulty staying at their posts for a full shift, and workers can suffer from headaches, nausea and eyestrain. Inspectors who are sensitive to flicker can exhibit an increase in speed, but a decrease in accuracy of performance when exposed to low frequency (120 Hz) flicker. Light flicker has a greater impact on people who suffer from headaches, stress and visual discomfort. When inspectors need lighting with high light levels, use electronic ballasts to operate the fluorescent lamps. This ensures that the flicker associated with magnetic ballasts doesn’t interfere with inspection tasks.