Technology news
INJECTION MOULDING
Ac-driven Machines Offer Low Energy Consumption and Ease of Maintenance
A series of injection moulding machines driven by ac motors offers significant improvements in energy efficiency. The EC-series moulding machines use separate ac servomotors for each machine function. When a function is completed or the machine is idle between cycles, the motors are shut off, contributing to a 60–80% reduction in energy consumption compared with hydraulic systems. The absence of oil reservoirs provides a further energy savings, and water use is also reduced by as much as 70%.
Toshiba Machine Co., represented in Europe by Stevens International Ltd. (Norwich, UK), reports that its electric series cuts operating costs by offering shorter start-up times and reduced reject and material scrap. Pat Fenn, a technical sales director at Stevens, says, "The advantage of the ac technology is that it is faster, more efficient, and more accurate than hydraulic processes."
The series also offers time savings, as less preventive maintenance is required to replace oil, water, and filters. Downtime for general maintenance and repairs is minimal. The machines are suited for cleanroom production and are available in 45-, 60-, and 110-tn models. The company plans to release 175- and 250-tn models later this year and 310- and 390-tn machines in 2000.
COMPONENTS
Miniature Dc Motor Achieves High Speeds at Low Temperatures
A 6-mm-diam brushless motor is reportedly the world's smallest electronically commutated dc motor with magnetic sensors. The component turns at up to 100,000 rpm and weighs only 2.8 g. Developed and manufactured by Maxon Motor AG (Sachseln, Switzerland), the unit is suited for use in infusion pumps and endoscopy applications.
The motor has a power rating of 1.2 W and operates at a low temperature. At a no-load speed of 80,000 rpm, the motor reaches a housing temperature of only 52°C. Constant performance can be achieved up to a maximum temperature of 125°C. Magnetic Hall sensors supply information on rotor position and help the drive achieve precision and a good start-up response.
The nominal voltage is 9 V dc. As with other dc motors, the operating voltage varies within a wide range. The maximum continuous current is 500 mA, and maximum continuous torque is 0.260 mN•m. The company is currently working on a range of 6-mm planetary gearheads for applications requiring higher torque at lower speeds. Suitable electronics are also available.
SOFTWARE
Database Combines Selection of Materials, Shapes, and Manufacturing Processes
Database software described as the world's first complete computer-aided engineering selection system enables engineers to translate design requirements for a given application into suitable materials, shapes, and manufacturing processes. According to Granta Design Ltd. (Cambridge, UK), which markets the product, the Cambridge Engineering Selector (CES3) can help maximize performance while minimizing costs.
"There are tens of thousands of materials, thousands of standard structural shapes, and hundreds of manufacturing processes to choose from," says professor of engineering at Cambridge University and company chairman Michael Ashby. When you factor in the pressure to increase system performance, reduce costs and weight, and minimize environmental impact, "even the best-informed engineer can know only a fraction of the available information," he adds. CES3 proposes to fill this gap by arming "the engineer with a full arsenal of information and analysis," says Ashby.
The CES database comprises validated records of materials, manufacturing processes, structural sections, suppliers, references, uses, and industrial sectors. It is accessed by means of an intuitive graphical selection method that was developed by Ashby and his collaborators at Cambridge University's engineering department. One of the unique features of the system is that users can customize and extend the database to suit their own particular needs. In addition to accessing supporting documentation on CD-ROM and the Internet via Granta's Weblinks system, engineers can edit existing databases or create their own. The CES Constructor package incorporates automatic data checking, and the databases can be read immediately by CES3.
Qualified individuals may request a complimentary demonstration CD-ROM of CES3, which supersedes the company's Cambridge Materials Selector and Cambridge Process Selector.
