If you think you’ve done everything you can to boost quality and productivity in your plant—worker training, statistical process control, computer integration—just glance up at the ceiling. The lighting under which all of your quality practices are taking place may be preventing total success.
Through well-meaning but misguided attempts at energy conservation, or through simple neglect, many “modern” plants are operating with substandard lighting. Studies have shown that lighting quality that has been compromised in the pursuit of energy savings has caused productivity to fall by as much as 28%.
Better lighting can make a substantial difference in the effectiveness of visual inspection. The right type of lighting, together with flexible fixtures, makes it easier for workers to see what they’re assembling or inspecting. With the help of professional lighting consultants, a specific form of lighting can be developed and applied to best illuminate finished goods for the conditions under which they’re inspected, and to minimize the likelihood of problem products finding their way to customers.
At Superior Pipe Specialties, Cicero, IL, workers engage in basic heavy-metal operations such as welding, forming, and intricate bending for pressure boilers. New lighting generated an average 2%-per-year productivity improvement throughout the 31,750-sq. ft. facility, creating net savings of $32,000 per year. Rejects were also greatly reduced, and rework savings added another $48,200 annually. The new lighting was almost 27% less costly to operate and maintain, saving $3,361 per year. All told, Superior’s $39,765 investment in new lighting was paid back in 25 weeks.
At Metal Industries Inc., Elizabethville, PA, energy consumption and maintenance costs actually rose, because a supplemental lighting system was needed to provide additional illumination to support the tasks involved. The manufacturer of metal-framed windows and patio doors had been relying on outdated fluorescent fixtures that didn’t produce enough light. The new lighting scheme called for the installation of 70 high-pressure sodium fixtures to supplement what already existed. The result was extensive and immediate. According to Sam Sitlinger, plant manager, productivity improved by at least 5% overall. That benefit alone was worth $1.5 million annually. The overall reject rate was reduced by 25%. Reduced rejects added another $200,000 to the benefit mix each year. Fewer accidents contributed another $3,000 to benefits annually, with lower insurance premiums doing the same. In addition, reduced absenteeism (due to fewer accidents) added $225,000 more in savings. All told, better lighting created a $1,931,000 benefit which, when the additional energy consumption and maintenance costs were subtracted, netted out to $1,911,140 annually. Consequently, the company’s $8,050 investment was repaid in 37 hours.
At Superior Die Set Corp., Oak Creek, WI, the productivity improvements realized due to improved lighting were worth more than $37,460 annually, supplemented by downtime savings of $5,376 per year. In the drafting and engineering area, the solution was less light, not more. “There was so much light bouncing off the [drafting] paper that contrast was being eroded,” said Casey Janiszewski, president. “The details on the surface of the paper were being washed out. … We provided better seeing conditions so drafters could reduce their errors.” New ballasts and current-limiting capacitors reduced energy consumption and lowered lighting levels. Not as easily computed were the values of error reductions, reduced absenteeism, and enhanced plant security. Lighting-system modifications cut annual operating and maintenance costs by 45%, to $2,148 per year. The $2,980 that Superior Die Set invested in better lighting paid for itself in less than 24 days.
How can you begin analyzing your plant lighting? Start by asking, “Why do we have lighting here in the first place?” Once you consider the answers, the goals of your new lighting system should become obvious:
• to improve the speed with which workers get their work done • to improve the accuracy with which workers get their work done • to help workers get their work done more safely • to provide a visual environment that is conducive to high morale, among many
other objectives.
Some plant managers pursue lighting-system modifications from a misguided costs-only point of view. They assume that “light is light,” just as “heat is heat.” However, lighting is far more complex than many realize. Factors that need to be considered include:
The quality and quantity of illumination. The areas of most concern from a lighting standpoint tend to be workstation or task surfaces, since illumination there has a direct and immediate impact on productivity and error rates. If an insufficient amount of light is provided, poor visibility forces workers to perform more slowly and make more mistakes than they otherwise would. Older workers are far more susceptible to glare and other lighting effects than their younger counterparts, and therefore need better quality lighting to produce at the same level.
The type of light. Shadows, glare, and reflections must usually be minimized, but lighting that causes glare might actually be preferred when it comes, for instance, to checking the paint on certain metal surfaces. In other words, what’s needed is lighting designed to deliver the type of light optimally suited for the tasks and workers involved.
Flexibility of lighting. Given that multishift operations may involve different workers performing the same task in the same space at different times of the day, flexible lighting is particularly important. Flexibility can be attained through lighting controls that can easily increase or decrease the amount of lighting from a given luminaire (fixture), and/or luminaires that can be easily moved. Developing a high-benefit lighting system—one that provides optimal “seeing conditions” while also consuming the least amount of energy possible for such a system—takes time and effort. No one specific approach is suitable for all plants. Each situation is unique, in terms of space, workers, and tasks involved. Attaining the best possible lighting scheme typically begins as a collaboration between plant management and lighting-system professionals. Plant-management personnel need to inform lighting professionals of the specific goals they want to achieve. Lighting professionals can then identify options for attaining those ends.