ACE Issue 23 2019 | Page 25

controlled press-in operation onto the mechatronic SCHUNK PPU-E 15 Pick & Place unit. For the freely programmable pacemakers, position and speed can be flexibly varied. The unit gently moves into the appropriate tool, then bends and presses the elements with a precisely adjusted force, before the axis returns to its original position at maximum speed and places the part onto the pallet of the linear transport system. The PPU-E, which is linearly directly driven and thus transmissionless, is currently the fastest Pick & Place unit on the market, whereby the size is specially tailored for use in electronics and small parts assembly. Due to a width of only 60 mm and a complete media feed via the back panel, it enables a particularly compact system design. For a complete cycle with a 145 mm horizontal and 45 mm vertical stroke, the productivity booster only needs 0.6 s for 1 kg additional mass and 2 x 50 ms gripping time. At its peak, the PPU-E 15 delivers a whopping 100 picks per minute. Such high numbers of cycles are not required at LEM. It much more depends on the smooth motion profile and the repeat accuracy of the axis, which is 0.01 mm. The smoother the movements of the individual handling systems, the lower the vibrations of the entire system. That's what LEM is all about. The smoother the movement curves, the more reliably the high quality of the electronic components is achieved. For example, the tolerance in the flatness of four bent contacts is just 0.015 mm. This is exactly why LEM uses the strengths of the SCHUNK PPU-E for. Instead of using a tolerance and wear- prone transmission of movement, the unit is moved by a wear-free direct drive. This minimizes the maintenance effort, increases the permanent repeat accuracy, and simplifies the individual programming. To increase process stability, both horizontal and vertical motions can be monitored with an absolute path measuring system. Air-sprung test station LEM goes a step further with two test stations for optical inspection of the components: "Here we need speed combined with a particularly gentle movement," Frédéric Cattaneo explains. 2D and 3D cameras capture the components highly accurately on all sides, measure the contacts and check the evenness of the previously bent elements.