FEATURE Drives, Controls & Motors
Five questions to ask before buying a geared motor
Marek Lukaszczyk, European and Middle East Marketing Manager at WEG, gearbox, motor and drive manufacturer, outlines the five key parameters to consider before buying a geared motor
T
he global geared motor market is expected to reach approximately $32.9bn by 2025. But, before plant operators and mechanical engineers invest in the latest geared motor technology, what are the key purchasing considerations? Gears are among the most important components in many drive trains. They are primarily used in combination with an electric motor to set machines and systems in motion and keep them moving. Due to the large number of geared motors on the market, there are countless technical characteristics that can be used to assess the quality, reliability and cost- benefi t ratio of a geared motor. So, where do you start?
1. Does the geared motor offer an optimal cost-benefit ratio? Naturally, a gear unit with a good cost- benefi t ratio will be preferred to a gear unit that performs very well but is too expensive to run. Maintenance costs are an important segment of lifetime costs. If a gear unit is particularly robust and dependable, it results in fewer callouts and has a positive eff ect on system availability. Lifetime lubrication, for example, is a good low-maintenance indicator that could make a huge diff erence in cost of ownership.
It’s also important to consider the application’s technical requirements, as if these are not optimally met, additional long-term costs can be incurred. Factors such as power, speed and torque are fundamental to any application and directly aff ect the size and costs of a geared motor. If, for instance, the combination of motor and gear unit is incorrectly selected, energy effi ciency is signifi cantly reduced, which will have a negative eff ect on the cost-benefi t ratio.
2. Which gear unit best suits my application? In industry, gear drives are primarily used, which include helical gear, bevel gear, parallel shaft gear and worm gear units,
20 February 2021 | Automation
which make up the majority of all installed gears, with planetary gears used to a lesser extent.
Design diff ers depending on the application, but all conditions need to be taken into consideration, including space requirements, drive output, drive control and ambient conditions. To make the right choice, it should also be clear what loads the gear unit will be exposed to. The spatial conditions of the application and the installation dimensions of the geared motors are key factors, especially when retrofi tting.
Design specifi cations such as diff erent coating systems, the protection class, as well as the type of shaft seal rings and shaft material, should be considered depending on where the unit will be used. While there is no ‘one size fi ts all’ response to this question, the more clearly defi ned the initial specifi cation, the less modifi cations will be required.
WG20 geared motors
to their winding design. WEG’s EUSAS motor is a good example of a versatile option that can be used in Europe, the US and Asia.
4. Is the gear unit energy-efficient? Effi ciency is very important – both for environmental and fi nancial reasons. While energy-effi cient products may have a higher cost, they have clear cost savings and environmental benefi ts in the medium to long term. In fact, energy costs account for approximately 90% of the total life cycle costs of geared motors. Modern gear units are ultra-effi cient: Only about 1.5% of dissipated power is assumed for each ratio stage. With a good gear unit, the developers will have analysed and optimised potential sources of dissipation, for example by reducing the gear splashing losses. Combined gear units off er effi cient power transmission with IE3 or IE4 mounted motors for the ideal solution.
3. How can I identify a good gear unit? When purchasing geared motors, certifi cations are important, especially when they are destined for worldwide use. For example, the CE marking is mandatory for Europe and proves that the product meets the applicable design requirements. In addition, the versatility of the unit must be considered. There is no global standard line voltage and it can vary signifi cantly depending on the country concerned. A versatile unit will cover the line voltages in use in the major global markets (110-690V, 50/60Hz), meaning that it can be used worldwide with simple voltage switching. This reduces the expense considerably, as many asynchronous motors are very limited in terms of voltage switching due
5. Is my manufacturer’s global supply chain and service reliable? Finally, if your equipment unexpectedly fails, the fast delivery of spare parts is crucial to avoid unnecessary downtime. Effi ciency in the supply chain shouldn’t be ignored at the procurement stage. When faced with the decision between an inexpensive gear unit, which cannot be delivered quickly, and a slightly more costly unit with a reliable and rapid global service network, the latter off ers a better cost-benefi t ratio. The former could result in productivity losses, not only to the company but also its customers, which could have negative implications for the company’s reputation.
It’s only when these characteristics are considered together that a plant operator or mechanical engineer can truly make the best purchasing decision.
CONTACT:
WEG
www.weg.net
automationmagazine.co.uk
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