Electromagnets (solenoids) are widely used today in a wide variety of actuator and sensor applications. Electromagnets are inexpensive, but also energy-hungry - nevertheless, many of their applications are justified and are the technical solution of our time.

However, especially when it comes to high packing density, engineers and system developers repeatedly come up against the limits of what is physically feasible. A large number of solenoids in the smallest possible space is exclusively accompanied by unpopular compromises. The reason for these limitations is the physical functioning of the solenoid itself:

Strictly speaking, a solenoid is a cylindrical coil with windings attached side by side, through which a homogeneous electrical current flow. This current flow generates a magnetic field that sets the core in motion. This magnetic field is generated in all directions and, with a high density of positioned coils, causes massive inductive couplings.

Precise positioning or optimal sensing becomes impossible. The same physical effect that sets an electromagnet in motion also defines its limits in an application. The heat generated at high packing densities also deserves special attention in the development of reliable microelectronic systems.

Energy-efficient solution for fastest movements in high packing densities:

Piezoelectric Actuators

Using the example of single needle selection systems the advantages of piezoceramic actuators are demonstrated easily: 

The piezoceramic actuator benefits from several physical advantages (compared to solenoids) in electronic single-needle selection: low energy requirements, elimination of the cooling that was once necessary, the compact design and positioning at very high speeds allow high packing densities. The long service life of well over a billion switching cycles combined with maximum reliability round off this field of application of our actuator solutions in a customer-oriented manner.

Johnson Matthey Piezo Products has been designing and producing SITEX modules for electronic individual needle selection in circular knitting textile machines since the 1980s.

Since the 1990s, our piezoelectric needle selectors have been appreciated in Jacquard machines, Raschel machines and warp knitting machines. In all areas of electronic needle selection, our technology around piezoelectric ceramics has been able to compensate for the disadvantages of solenoids and provide on top for increased productivity, best energy efficiency with maximum reliability.

Under these demanding environmental conditions, piezoelectric systems are the energy-efficient solution for fastest movements in high packing densities. Efficiency, high reliability as well as high durability of piezoceramic-based technologies are side-effects of our innovative systems. In close cooperation with leading manufacturers of textile machines, we continuously develop individual solutions that meet our customers' requirements and ensure maximum productivity.

A SITEX® module, used within circular knitting textile machines, consists for example of the “Piezoelectric ceramic bending actuator“ component, mechanical parts and driving electronics. Optionally we can add a control computer to the system. We work closely with our customers to achieve the best possible solution for their requirements.