Automation can produce large quantities of product quickly, but ensuring end-part quality is a critical challenge. Visual, manual, or periodic sampling methodologies can be imprecise, slow, or come in too late to trigger a timely line stoppage once a manufacturing error has occurred, resulting in a high proportion of discarded parts.
An electronics-connector manufacturer was looking for an automated solution to effectively carry out inspection on 100% of its products directly on the production line. The part in question consisted of a small base plate on which a large number of metal pins were mounted and then over-molded with plastic. If the metal pins were in any way deformed or moved out of position during manufacturing or the subsequent molding process, the current production equipment could not detect this before the part went into an automatic-insertion machine. The issue was not the low-cost connector itself — it was the potential coupling of a defective connector with another one or even a jammed, high-speed machine and complete line shutdown. Such scenarios could arise if even a single pin on one part was out of alignment.
The solution was an automated inline computed tomography (CT) system, coupled with scan-data analysis software tailored to the exact speed and efficiency metrics of the connector manufacturer’s automated production process (which is less than 10 seconds per part). Located at the point where the finished parts emerge on a conveyor belt, the system rapidly CT-scans each part to provide both surface and internal X-ray views of the complete part volume. This data is then transferred (as an STL file) to a nearby computer loaded with Volume Graphics VGinLINE analysis software.
The software (pre-configured with the manufacturer’s macros and parameters) compares the geometry of each connector against a “golden mesh” — an adaptation from the original CAD design of the part that takes into account the realities of the pin-manufacturing process — and identifies any variances in connector-pin structure or alignment. If a single pin is found to be outside the pre-determined tolerance limits, the entire connector is rejected by the software and automatically gated off the assembly line.
Customizing the CT scanning process for an individual production line in this way requires answers to questions such as how quickly the line is moving and how fast the scan needs to be done. What kind of information needs to be taken from the scan and what will be done with the information afterwards? What are the tolerances within the parts being produced and how much variance is allowable?
The ability of CT scanning to non-destructively “see” deep inside objects allows this kind of system to be used for quality control on manufacturing lines across many industries. The setup can evaluate parts made from almost any material, no matter how complex in shape. VGinLINE can be used for detecting porosity, delamination, and a wide variety of other types of defects anywhere within the part. If it is required to evaluate the extent to which variations in part geometry affect performance, related software can be used to perform a realistic micromechanics simulation or to generate a high-quality tetrahedral volume mesh for further use in third-party FEM simulation software.
As the automation of factories continues to expand, the economics of implementing reliable, repeatable quality control directly on the manufacturing line is increasingly making sense to high-volume part-production companies. Industrial CT systems and associated software are being installed all over the world as more manufacturers decide to make the technical investment to integrate this technology with existing production lines. A significant driver for the adoption of in-line scanning is the leap in data processing speeds; in one instance, a system is meeting a tact-time requirement of 5 seconds per part (CT scan, analyze, accept/reject).
This article was written by Peter Davis, CT Automation Manager and Jake Rickter, Automation Specialist at Pinnacle X-Ray Solutions, Suwanee, GA. For more information, visit here .