MRO Magazine

Gearing That’s Green

Manufacturers who want to compete globally have to go ‘green.’ Why? Because being environmentally friendly with highly-efficient, reliable and durable gearing and components means higher productivity, energy savings, less downtime...


Environment

February 1, 2012
By MRO Magazine

Manufacturers who want to compete globally have to go ‘green.’ Why? Because being environmentally friendly with highly-efficient, reliable and durable gearing and components means higher productivity, energy savings, less downtime and more profits for the end user.

Several industries have shown how excellence can be achieved by making reliability and durability primary objectives; examples include aerospace, automotive, military and even some consumer products companies.

In one example, Stober Drives Inc. of Maysville, KY, has conducted customer energy audits and found that many factories and food processing plants are operating equipment at 60% to 70% efficiency – which is like driving a car with the parking brake on.

Manufacturers need to modernize assembly lines, too. Endless miles of conveyors and equipment across the country are driven, in many cases, by inefficient motors and even more inefficient gear drives. Many of these inefficient gear drives use outdated worm and spur gearing, not highly efficient helical gearing.

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Helical gearing is machined with angled teeth, then hardened and ground, a complex process, but necessary to achieve high-efficiency gear meshing. Teeth are cut across each gear at an angle so gears gradually mesh. Because of the angled teeth, two or three teeth of each gear are always in contact with other gears. This alleviates the load on each tooth and creates a smooth transition of forces from one tooth to the next. The result: less vibration, wear and noise – and longer life.

Helical gears are virtually maintenance-free; tooth profiles are so precise there is practically no gear wear. Since some units are packaged in sealed, oil-filled housings, no oil changes are required, which is a boon for the environment and the bottom line.

Engineers intuitively understand the advantages of green helical engineering because they understand two tenets of efficient engineering.

1. High noise + vibration = low precision and low productivity. Many factory components require high maintenance, monitoring and replacement. Yet equipment downtime costs factories immense amounts of money in lost productivity. When we look at automation, machines have basically two modes: a) Running efficiently and earning money, or b) Idle, down and unproductive, which costs money.

Several components are culprits for much of the maintenance and downtime in factories: bearings, belts, chains, wiring, electric motors and gearboxes.

Rotating machines that generate high noise and high vibration can have any number of quality issues: rotating components may not be balanced properly, which causes vibration. Mating components may be machined to tolerances that are not precise enough regarding perpendicularity, concentricity and true position. Or components may not be rigid enough, flexing under load, which results in misalignment.

Helical gears are virtually silent, which is good news for employee hearing. The noise level of helical gearing is approximately 10-12 dB(A) lower than spur gearing. In terms of human noise perception, that means 16 helical gear units generate as much noise as a single spur gear unit.

2. High heat generation = low efficiency and wasted energy. High heat generation is always the result of low efficiency in rotating machines, and this can have many causes, including inefficient design, misalignment, incorrect fits and large seal diameters creating drag.

Helical gearing is 20% to 30% more efficient than single-stage worm gearing (see Fig. 1). With a 2-hp motor, up to 4,000 kWh of energy can be saved per year. Additionally, often you can go to a smaller motor because the losses in the gear reducer are lower, saving on the initial investment.

The ability of factories to compete globally depends on their ability to increase productivity. Productivity is driven more and more by machine quality, cycle times, durability and reliability. Labour efficiency is certainly important to all businesses, but since many manual labour jobs have gone offshore, the majority of productivity gains must come from highly efficient automation on factory floors. Focusing on high-quality, efficient, reliable and durable components is critical.

As we build and retool factories, productivity is the key to competing against low-wage labour markets. Highly productive and efficient equipment saves money, energy, materials and time. Going ‘green’ by using highly efficient machinery that saves energy, lasts longer and operates with little downtime is the best opportunity stay competitive in the global economy.

MRO

Established in 1991, Stober Drives Inc. is based in Maysville, KY. For more information, visit www.stober.com.


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