SMAC develops ultra-high-speed pick-and-place

SMAC has helped to develop an ultra-high-speed, three-axis pick-and-place system for a multinational Japanese manufacturer of luxury goods that was seeking to both increase product output and improve the flexibility of the manufacturing process. SMAC's strengths are in moving coil actuator (MCA) technology, and the company claims that its actuators are unique due to the fact that the speed, position and force are fully and independently programmable - all at the same time.

Customer requirements

The customer required a number of different sized, high-value micro components to be picked and placed at high speed. The weight of these components is only a few grams and they are extremely delicate - and therefore difficult to handle. The X axis of the system has a stroke of 50mm, the Z axis 30mm and the theta (rotary) axis 360 degrees. The system is required to use the Z axis actuator to pick up the micro component with vacuum using SMAC's patented Softland function before releasing the vacuum and lifting off to ensure no damage to the component occurs during pick-up. Then it is required to rotate the component 180 degrees to ensure the component is in the correct orientation for placing. The X axis then moves 100mm into position and the Z axis then places the component in position - again using the Softland function. Both the start and target positions are reported to guarantee the correct placement of the part.

After all this, the system returns to the start position and repeats. The complete cycle time is less than 300 milliseconds, which equates to three cycles per second. The customer's existing system was running at a cycle time of 900 milliseconds using conventional pneumatic devices and servo systems with external electrical sensors and switches. By integrating force and position sensors into a single direct-drive device, a major step change in terms of speed and performance has been achieved and SMAC claims to have set a new standard in high-speed pick-and-place factory automation.

The specification

While the need for speed was paramount, the requirement for precision, accuracy and repeatability were even more demanding. The shaft run-out on the Z axis actuator was required to be

On the Y axis actuator (50mm stroke), overshoot was allowed and an accuracy of +/-10um on the settlement of the actuator. The rotary axis integrated into the Z axis actuator required an accuracy of +/-2 counts on an encoder with a resolution of 1um. This was necessary for settlement when flipping the component through 180 degrees. No external electrical switches or sensors were allowed and a duty cycle of 24 hours a day, seven days a week was required.

On top of this, the temperature of the system was not allowed to increase more than 20degC from the ambient at any given time. In all - an extremely demanding set of criteria regarding, speed, precision, accuracy, repeatability and durability.

Customisation

This highly innovative system was custom-designed by SMAC's design engineering team in Carlsbad, California, USA. The customer was supplied with a completely pre-assembled, individual parts handling system. It was designed to be quickly retrofitted into the existing production system within the customer's factory. One of the key features of the SMAC moving coil actuator system is that it has inherent positioning and feedback capability - a closed loop-system that ensures no external sensors or switches are required. This dramatically reduces the amount of external wiring required and facilitates both quick installation and 100 per cent diagnostic feedback and data reporting.

The system was rigorously tested in advance of delivery and was therefore ready to install as a turnkey unit. The pick-and-place system integrated two multipole moving coil actuators, one of which was a two-axis rotary unit. The Y axis unit - part number MLA15-50 - had a stroke of 50mm and the Z unit - part number MLRA15-30 - has a stroke of 30mm and an inbuilt rotary axis of 180 degrees. Due to the exceptionally high speeds and high duty cycle, air cooling was used to keep the temperature of the actuators constant. The electronic actuators achieve an exceptionally high degree of speed, accuracy and repeatability by the use of specially designed internal components and SMAC's high-performance electronics. 'C' sleeve linear guides deliver exceptionally high life expectancy and a high-resolution encoder is integrated. The SMAC system is complemented by four high-speed Galil electronic controllers.

Project results

The whole system, which uses proprietary SMAC technology, was taken from concept to delivery of a working system in under six months. The SMAC system surpassed the customer's requirements. It achieves 'perfect' quality and allows production times to be tripled. Further to this, it also enabled the customer to increase manufacturing throughput and flexibility by rapidly switching to new parts for different products quickly. Previously, manual machine changeover of parts was required. The SMAC system reduced existing cycle times from 900ms to 300ms while operating 24/7.

It is now claimed that the SMAC system sets a new benchmark as the fastest and most accurate pick-and-place machine automation system in the world. Due to the fact that it is SMAC's proprietary technology, it can be freely used for other customers and other applications. It is well suited to the handling of any micro components where fracture and damage occurs during the production process when using conventional systems such as pneumatic devices, ball screw and servo systems. It is highly suitable for SMT and chip-placing applications.