Advantages of 3D Vision for Adhesive and Sealant Dispensing
Due to the trend of light-weighting and electrification, adhesive, sealant and thermal inductive bead materials are becoming more widely used in the automotive design and manufacturing process. They are used for a wide variety of purposes, like bonding of dissimilar materials for structural rigidity, corrosion resistance, water seal, oil seal, fume seal, noise vibration and harshness (NVH) reduction, durability, thermal management and more.
The manufacturing process of applying the bead material is dispensing. In the automotive mass-production environment, dispensing is typically automated with a dedicated robot and dispensing equipment, which are intended to consistently deliver the right volume of the material at the right location. However, due to the many variations inherent with the dispensing processes and the limitation of the current automation equipment, dispensing has proven to be a poorly controlled manufacturing process.
Over the years the industry has tried hard to utilize 2D vision for the dispensing process, but this endeavor has not been very successful for many reasons:
First, volume is a 3D metric which requires a 3D inspection solution. 2D cameras cannot pick up the volume information by the essence of how they operate. The dispensing equipment can only provide total volume dispensed; it cannot tell how much volume is applied at what location.
Second, 2D cameras are typically implemented as a post-process, meaning dispensing first and then the 2D check afterwards. That adds significant cycle time, which most automotive manufacturers don’t have the luxury of. The 2D inspection station requires separate floor space, which is also very valuable in any manufacturing plant.
Third, most dispensing applications in automotive involve free-form parts with complex geometry. For this scenario, the 2D post and static inspection cannot even get to most sections of the bead unless it is carried by the robot for the cameras to pick up, which will add even more cycle time.
The last, which is certainly not the least, is the fact that 2D cameras’ working principle is based on the contrast of the grayscale images captured. With crucial production variations, such as ambient lighting changes, part color changes, etc., the contrast-based 2D cameras have been very temperamental dealing with these, which as a result increases the total cost of ownership and significantly reduces the productivity or the throughput.
With the reasons above, one can conclude that a robust 3D solution is required to manage the current dispensing challenges faced in today’s manufacturing process. The first step of the 3D solution is to provide robust inspection of the bead volume and bead location in real-time. This already sets a high bar, which means it will require special system design and sophisticated algorithms, and for that reason alone not just any generic 3D sensor can do the job. The next step of this solution is to use the 3D information to better control the dispensing processes as a whole.
Coherix Predator3D™ is a self-contained, around-the-nozzle robust solution for real-time 3D inspection and process control of dispensing in the real production environment and even has an optional auto repair function to increase productivity. It is specifically designed to address the challenges stated above.