A quality brazed joint doesn’t happen by accident. Brazing is inherently hands-on. To do it right, the process needs to be designed to the smallest detail, with ample allowance for quality control. After all, once components are brazed there may be no way to fix problems that should have been caught earlier.
Stop points are a crucial component of quality control for brazing and many other manufacturing and finishing processes. Stop points offer the brazing team a chance to do several things:
- Fully inspect the parts to ensure the steps taken up to the stop point were completed correctly and without unexpected distortions, damage, or discoloration.
- Verify compliance with customer specifications.
- Prepare equipment with preventive measures such as high temperature burnouts and leak up rates.
Within each of these categories there may be specific steps dictated by where the part is in the brazing process. Here are a few examples of the many stop points we use at Thermal-Vac:
- Receiving. When parts are first received, a stop point is used to ensure the parts are counted, clean, in good condition, and manufactured to the tolerances necessary for brazing to succeed.
- After applying the braze alloy. Before parts are heated to brazing temperature, the braze alloy is inspected to verify correct application.
- After each thermal cycle. Many brazing processes require multiple thermal cycles, which can afford opportunities to inspect the work done so far. In addition to a close inspection of the parts themselves, inspectors will review data about the thermal cycle itself to confirm it performed as expected. This stop point also lets inspectors confirm that everything looks good for the next cycle to proceed.
- Final inspection. A final inspection involves a deep dive into the tiny details to confirm that the brazed joint has met a customer’s strength, hardness, dimensional, and visual criteria. Techniques like helium leak testing, radiographic, and ultrasonic testing are used to verify that the joint is void-free.
Stop points are among the important qualifying standards for manufacturers that meet the AS9100 standard for manufacturers in the aviation, space, and defense industries. At Thermal-Vac we have gone above and beyond certification requirements to incorporate stop points that our team has determined are necessary to prevent gaps in quality procedures. Every part we braze, whether it’s for a consumer product or a component headed to Mars, undergoes the same rigorous process. It’s the right way to do it.