Drive Technology Trends
By Masazumi Suzuki
Gear Drives are used in many different industries, from heavy industrial (steel, mining, forestry) to light industrial (automotive, food machinery) applications. Environmental concerns and attention t...
June 1, 2010
By Masazumi Suzuki
Gear Drives are used in many different industries, from heavy industrial (steel, mining, forestry) to light industrial (automotive, food machinery) applications. Environmental concerns and attention to energy savings are unavoidable in today’s manufacturing business. Global warming caused by the large industrial consumption of energy is one of the biggest environmental impacts on a global scale.
As a result, energy savings, high efficiency and recycling are becoming increasingly more important. However, with the current economic issues that surround the environment today, businesses must weigh their options with gear drives that are typically used in most industrial applications. One alternative is to opt for the direct drive technology that has started to penetrate through some markets. This article will discuss direct drive technology trends and investigate its potential impact on the gearmotor business.
Direct drive motor trends
Induction motors are commonly used in applications ranging from home electric appliances to industrial process equipment and provide advantages such as simple construction, durability, reasonable cost and ease of control. However, increasing the efficiency of induction motors has been difficult because of their large ther- mal losses due to current flow in the rotor.
Environmental and energy concerns are driving development of higher-efficiency motors due to the up to 70% of total energy consumption of the manufacturing market.
Direct drive motors are, by definition, motors that transmit power to the application directly, without the use of mechanical reduction elements such as gears, pulleys, chains or belts (see Figure 1).
In order for a direct drive motor to replace a gearmotor, it must be able to provide high torque at low speeds, which is not what induction motors are well known for. Therefore, most direct drive motors that replace gearmotors have some type of permanent magnet (PM) motor that is paired with an electronic controller.
There are several important key factors that need to be understood to explain why some industries are opting for the direct drive motor rather than the typical gearmotor.
First, direct drive motors have high efficiency, high precision, low vibration and fast response, and are compact, lightweight, quiet and easy to maintain. Why then, would anyone not want to switch to a direct drive motor?
Technology, even in the realm of motors, develops similar to the curve shown in Figure 1. This figure is a timeline of technology evolution known as an S Curve. If the S Curve exceeds customer needs, commoditization results, followed by severe cost competition and price wars.
It is said that the S Curve of the gearmotor business does not exceed customers’ needs, but is very close to the intersection of the two lines. On the other hand, direct drive motors are relatively new and are still in the developing stages of the technology evolution.
This can also be explained by utilizing the concept of product architecture. Figure 2 maps the customer value in the horizontal axis and product architecture in the vertical axis. The integrated type architecture requires custom designing and can be costly. The customer value is classified into ‘well-defined/general requirements’ and ‘potential/custom requirements’. It is thought that gearmotors are classified in Quadrants 1 and 2.
By contrast, direct drive motors are still custom-designed and have an integrated architecture. Based on this product architecture in respect to the gearmotor market, the cost of direct drive motors may shift into Quadrant 2 in the near future.
Time will most likely be required for direct drive motors to modularize and become standardized, because these designs are still developing and current options are still fairly flexible. There are various speed and torque characteristics, motor design architectures and motor control schemes available.
Will gearmotors be replaced with direct drive motors?
Direct drive motors create new customer value, as mentioned in Figure 2, and although costly, many customers have realized the benefits of switching over to this new technology. If a customer’s value is mapped within the concept of a Value Network (Figure 3) that shows time in the horizontal axis, the function (value metrics) in the vertical axis, and the value network in the axis perpendicular to the page (z-axis), the value networks of both products can be shown in relation to one another on different planes.
The different customer needs are dotted three-dimensionally around the customer- needs line. Likewise, the different variations of the products are distributed three-dimensionally around the product technology evolution line. As time progresses, the customer-needs line and the product technology line begin to approach one another or separate from one another.
Currently, the value metrics we can identify for the gearmotor network are (1) reasonable life, (2) high reliability and (3) reasonable cost. On the other hand, value metrics identified for the direct drive motor network are (1) high efficiency, (2) high precision, (3) quiet operation and (4) maintainability.
As previously mentioned, direct drive motor technology is still in the developmental stages of the technology evolution and is yet to be modularized. Therefore, it can be said that direct drive motors are only used for specialized applications for high-end users and the size of the direct drive motor market is still relatively small.
The gearmotor market as a whole incorporates a wide range of applications, some of which are well outside the realm of the direct drive motor market. If we restrict the study of the gearmotor market to only that involving speed control, gearmotors still provide a more practical advantage.
Gearmotors are a moving target and can still be paired with PM motors to improve efficiency. Also, new lubrication technologies are continuing to improve gearbox efficiencies.
Direct drive motor applications that can accept tradeoffs between high efficiency and high performance vs. high cost and integrated packages are still not commonplace. However, new values such as energy savings, sustainability costs, and improved performance due to growing attention to environmental concerns — such increasing CO2 emissions — may nudge macroeconomic factors to replace gearmotors at a higher rate.
Other factors that will direct the market towards a shift to direct drive motors could incorporate new technologies that include design and manufacturing techniques yet to be unveiled. Furthermore, governmental regulations and development of new industry standards may tip the shift towards more direct drive motor applications. Nonetheless, users should continue to watch macro trends for direct drive motors in the future.
Masazumi (Mack) Suzuki is an applications engineer with Sumitomo Drive Technologies. He has a Masters Degree in Me-chanical Engineering from Nagoya Institute of Technology in Japan and over 13 years of mechanical engineering experience.
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