01 - the SHORT story

LEM Optical is a company in Galliate Lombardo in Italy manufacturing high-performance eyewear and ski goggles for leading eyewear brands. Key challenges such as competition from countries with lower labor costs, growing demand for model variations, and generalized cost cutting  led LEM to move rapidly towards automation. The company has now deployed four Universal Robots in laser marking, dispensing and in the tending of injection molding machines.

02 - THE CHALLENGE

LEM Optical, a manufacturer for some of the most highly regarded sports eyewear brands, decided to introduce collaborative automation in response to a number of application challenges. So far the company has installed four Universal Robots collaborative robots on 3 different processes. Each process presented a specific challenge.

1. Laser lens marking: the challenge on this application was to keep a constant distance between the laser focal point and the cylindrical lens, interpolating the laser beam with the movement of the lens to ensure marking of the entire surface.
2. Dispensing of water-based glue: a specific amount of glue had to be applied to the foam padding of ski goggles, along a pre-set trajectory,  avoiding some areas of the padding. The application also had to meet a series of weight/footprint criteria since it was installed on a mezzanine floor unable to accommodate heavy machinery.
3. Tending of injection molding machines: the challenge was to automate an unergonomic operation and optimize cycle time and efficiency.

03 - THE SOLUTION

LEM Optical went to Alumotion, an official Universal Robots distributor, to handle the integration of the cobots and automate the three processes.

Collaborative laser marking

For the laser lens marking application, two UR3 cobots have been installed in two identical cells. The cobot picks up the lenses (already inserted in the frame of the goggles) with a vacuum gripper developed separately by LEM. It then places the lenses under the laser and moves them so that the distance from the focal point remains constant, ensuring that the blade acts around the edge of the lens to mark it. At the end of the cycle – which lasts about three minutes to complete the marking of both lenses – the robot places the lenses and the frame in a rack. The two cells are supplied by a buffer containing from 20 to 40 lenses each.

“We wouldn’t have been able to do this without the cobots,” says Stefano Lodigiani, general manager and co-owner of LEM. “Manually, it is simply impossible to keep a constant distance from the laser focal point, whereas the cobots guarantee the precision and repeatability we need to perform the process impeccably. Also – thanks to the two cells’ feed buffer – this phase is now fully automated. The operators carry out just two operations: loading the buffer about once an hour, and quality control. This has enabled us to optimize our workforce and assign employees to jobs with greater added value while maintaining high precision on this delicate operation.”

Glue dispensing

LEM’s core products include a number of ski goggle models. The application dispenses glue on a specific area of the foam padding to be glued to the frame of the goggles. As a result of a production parameter adjustment, the padding now protrudes by about two millimeters outside the frame: the glue has to applied only to the part that comes into contact with the frame. “Manually, it was impossible to perform this operation with the necessary repeatability, on an identical trajectory and at a constant rate,” explains Stefano Lodigiani. “So we installed a UR5 equipped with a dispenser fed from a tank, which distributes the glue on the padding along a trajectory that is always identical and at a constant rate. We have obtained a consistent, higher-quality product. Moreover, since this stage is performed on a mezzanine floor inside our plant, the automation had to meet specific weight and footprint conditions, given that the layout was already fairly full and the mezzanine could not be overloaded. The UR5 weighs less than 20 kg, we carried it easily up the stairs and installed it without difficulty.”

Tending of injection molding machines

The third and final application developed by LEM is tending of a injection molding machine. The machine molds the frames of ski goggles. A UR10 cobot places the male molds inside the machine, removes them when the cycle has been completed, and places them in a transfer area where the operator separates the mold from the finished frame. The cobot is fitted with a 4-point pick-up unit. With two points it picks up two empty male molds and places them in the machine; at the same time, the other two points remove the other two molds with the molded frame. The operator separates them and a new cycle begins.

“In this application, the cobot meets two main needs” explains Stefano Lodigiani. “It improves the ergonomics of the molding station (the molds weigh about 1 kg each, so the operator is required to handle about 4 kg of material every 60/70”) and optimizes the rate of production. Cycle time is fundamental in plastic molding to guarantee product quality: the cobot ensures that the application proceeds at a constant rate and pressure.”

04 - ADVANTAGES

The level of automation in the eyewear sector is still low. Many operations are performed manually. The use of collaborative robots has enabled LEM to achieve constant productivity and greater rationality in workforce management and to provide a number of customizations requested by clients, which would have been impossible to achieve manually. The cobots have also allowed the company to optimize some strategic processes thereby increasing productivity and end quality.