Solenoid provides a low cost alternative to pneumatics

Dean Palmer reports on a new, miniature range of solenoids that could offer machine designers an accurate, repeatable and cost effective alternative to pneumatics A new range of DC solenoids has been launched in the UK which offers machine designers and factory automation engineers a reliable, accurate and cost effective technology for on-off applications such as latching and triggering. While most other solenoids only achieve a maximum stroke length of 25mm, Isliker Solenoids' new KGS range of DC solenoids can offer designers stroke lengths of up to 50mm, a linear force that can be delivered as either a pull, thrust or rotary motion. Roy Walker, UK sales manager at Isliker Solenoids told Eureka: "The low cost KGS range will meet a demand for a reliable every day DC solenoid which provides high quality precision day in, day out on machinery performing a variety of duties." He mentioned various applications for the solenoids including medical equipment; laboratory equipment; security locking and access control; remote switching of electrical switchgear; heavy artillery firing pins, printing stack joggers; paper handling mechanisms, vending and amusement machines; money counting and for HVAC air diverter flap control. "The miniature unit is a pull solenoid or push on request, that comes in several envelope sizes and is specially treated to make it corrosion resistant," added Walker. "In the medical industry, it will be used to move mirrors and to perform dental machinery applications. The units can also be used to activate locking devices such as those on hotel doors or as positioning devices or reject mechanisms on packaging, wrapping and palletising machines." According to Walker, a solenoid is basically a specially designed electromagnet that converts electrical energy into straight line motion. A solenoid can be wound to accept either AC or DC voltage. He continued: "Linear solenoids can be of open or closed frame rectangular construction and if required the coil can be encapsulated to prevent humidity ingress. Rotary solenoids will deliver the force in a rotary direction and it must be specified whether the rotation is clockwise or anti-clockwise." The three main parts of a solenoid are the frame, the coil and the plunger. As Walker explained: "The plunger is not fixed in the unit and must be prevented from falling out of the bore of the coil when it is de-energised. Our design incorporates a method of plunger retention if no external means is available. If the coil is de-energised after the plunger has travelled its stroke length, the plunger will not return to its starting position unless a return spring is used. This spring can be included as part of the solenoid design and can usually be fitted at either end of the frame." There are several unique design features worth mentioning about the KGS range. First, the plunger is supported on a bearing surface to facilitate extra long life - up to "many millions of cycles" according to Walker. Second, the units can be sealed to IP65, with stroke lengths up to 50mm. And third, the solenoids can be supplied with permanent magnet capability, providing pull, push, double action, bi-stable or latching motion. The miniature KGS solenoids are available in AC or DC voltage, with pull or thrust forces up to 1,600N. The units can operate in temperatures up to 155°C, torque is 6 to 190N with strokes from 6 to 20mm. Pointers * Motion can be as a thrust, pull or push with maximum stroke lengths up to 50mm * Applications range from simple security locks and access control through to printing, paper handling and medical equipment. * The plunger on the solenoid is supported on a bearing surface resulting in extra long life up to 'many millions of cycles'