Different requirements are placed on linear units in process automation. Aspects such as speed, payload, accuracy, stroke length, reliability and robustness as well as area of application and duty cycle determine the selection and design. Online tools offer support in the complex selection, design and configuration of mechanical components and systems. For some applications, a parallel arrangement of linear units is necessary if, for example, synchronous movement of both units in one plane is required. To implement this technically, it would be possible to equip each linear unit with its own drive and install a PLC to control the entire synchronization. However, it is simpler to connect the linear units to each other via a shaft and use a single motor. However, the design is then complex. "Automation is easy with the Item Motion Designer," says Uwe Schmitz, Team Leader Product Management item linear motion units at Item. "A single online tool covers various automation tasks, perfectly tailored to individual mechanical and electrical requirements."

Mechanically synchronized linear units can be designed with the Motion Designer to match the transport task. The intelligent program determines the combination of two linear units and a synchronous shaft, which enables two slides or two linear units to run in parallel. "The modular system offers ready-made solutions for a large number of linear units," explains Uwe Schmitz. "These consist of couplings that are mounted between two linear units and connected to a synchronous shaft." The couplings are matched to the linear units. Two metal claws enclose a plastic coupling ring gear, which compensates for axial and radial misalignment.

2D surface portals in systems for printing or inspecting surfaces can be implemented quickly and easily with the item components. © Item

Various gantry solutions are available for the automation of production processes with parallel linear units. These are combinations of linear units with which numerous tasks can be realized, for example the control of different points in a plane by a tool. Two axes then run in parallel and are connected by a synchronous shaft. These 2D surface gantries are used, for example, in systems for printing or inspecting surfaces. Here, probes, sensors or print heads move precisely over a large area. Ideal combinations of linear axes are also available for 3D spatial gantries. Demanding positioning tasks can thus be performed in three dimensions. Synchronized linear axes can be used to design pick-and-place systems, for example, in which grippers and tools for processing tasks are attached to slides and carrier profiles.

Complex task
When designing synchronized linear axes, designers have to take many influencing factors into account. The installation position, dynamic parameters, occurring loads and forces play a major role. The length of the synchronous shaft must be determined depending on the maximum possible speed. Torques can be calculated and suitable couplings selected on the basis of data sheets. In order to achieve an optimally functioning system, the selected components must also be mechanically combinable. "The linear unit is often designed based on corresponding corner points and tends to be oversized for safety reasons," explains Uwe Schmitz. "However, a generous design goes hand in hand with additional costs." If, on the other hand, the system is not sufficiently dimensioned, defects, downtimes and inefficient processes are the result.

With the design of the linear units, speed, precision and load capacity are optimized and the system can be operated efficiently in the long term. Item's online tool makes it easier to dimension and select components. "The Motion Designer calculates the maximum torques, for example, and recommends the solution with the right coupling," says Uwe Schmitz. The software's comparison function shows both the technical requirements defined by the input and the technical specification of the system that Item recommends. The designer can choose between the system that exactly meets his requirements and alternatives that offer more performance reserves. Item thus automates and simplifies the specification of systems and provides an optimally dimensioned overall solution including synchronization set, motor, gearbox and control system. The designer automatically creates complete documentation with all technical specifications and CAD data. In addition, the designer can access numerous application examples including design data. as