For complex plastic injection molded parts, mold qualifications can run for weeks if not months. Industrial CT scanning saves hundreds of hours during qualification and has become the most popular choice for companies that want to get their products to production fast.
Once a part is designed and the mold is built, an FOT or first run is done to check that the mechanics and electronics of the mold are working properly and that there are no large defects on any of the parts. Next comes the process development phase, where specific settings are designed to fine tune the molding process. These settings include pack pressure, pack time, melt temperature, mold temperature and cooling time, among others.
Parts from several processes are visually inspected and the best parts chosen to be sent to more formal inspection. These parts are inspected by calipers or optical measurement systems. Traditionally, the data is reviewed and an educated guess is made about the best process. The best parts from the best process go into full first article inspection. Programs are created around the part, fixtures are engineered, built and adjusted to align the part, and physical cross sectioning may be needed to cut sections, inevitably changing the free state of the part.
If a first article inspection does not pass, readjusting the process and fixture adds more time to the schedule. When getting parts to production fast is crucial, finding the best process and qualifying molds must be done quickly and efficiently.
Industrial CT scanning saves time and helps you make better decisions faster during mold qualification.
Before going into a full first article inspection, CT scanning the best processes and creating part-to-CAD overlay comparisons can quickly determine which process yields parts closest to the intended design. Knowing the best process changes the first article inspection from an investigation exercise to a confirmation exercise.
With advanced software, programs are created using only the CAD model and part drawing without the parts in hand. This advantage allows programming to be done before or while the mold is being built, saving hundreds of hours from the project timeline. In addition, parts are scanned non-destructively in their free state and the 3-D point clouds are aligned virtually, removing the need for fixtures and physical cross sectioning. All CT scanning inspections are accurate within 5 to 7 microns.
Below we see two mold qualification timelines using traditional metrology and industrial CT scanning. In this case with traditional metrology it takes 27 days due to long first article inspections that require custom fixtures, resampling or readjusting of the process, and further inspections. With industrial CT scanning it takes only 13 days because a part-to-CAD overlay determined the best process before inspection, then parts were scanned without fixtures in their free state. Also the program was created weeks ahead of time, meaning inspection results were able to be generated in one day.
After mold qualification is completed and the mold is transferred to the manufacturer, a part-to-part analysis is done to make sure that the process of the manufacturer is the same as the process of the mold builder. This is done by scanning both parts, setting up one as the standard and overlaying the other one on top to see how similar or different they are.
During the IQ, OQ, and PQ runs, first article inspections run at a much faster pace because the program for inspections is already completed and can be used at any point in the future. With traditional metrology methods results would take days. But with 1 hr scans and an inspection program ready to run, industrial CT scanning results are generated in a matter of hours.
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