The Problem:

A Prince & Izant high-volume automotive customer was experiencing quality issues with their copper brazing paste application. After a materials analysis determined that the paste metal load and viscosity were within specification, an onsite visit was scheduled to observe the brazing process.

Before the visit, P&I Engineering assessed the factors they needed to consider to evaluate the customer’s specific brazing process. Braze joint design was evaluated and deemed to be appropriate for the application. The following factors were isolated as likely contributors to the fall-out. 

  1. Placement of brazing paste
  2. Volume of paste used on joint

The Process:

P&I Engineering met with the customer to run through the details of the process. First, an overview of the customer’s braze process was provided, giving part and product-specific details. Next, our engineering team analyzed the brazing process in its production environment. Lastly, P&I Engineering provided a detailed report with helpful recommendations for modifying the customer’s brazing paste application process.

The Findings:

The customer was using a manual method of applying copper brazing paste to a vertical braze joint surface, which was then brazed in a belt furnace. During the brazing cycle, the manually applied paste appeared to lose viscosity and move out of position during preheating, causing the customer to repeat the first steps of the process. It was also noted that while the manual application of braze paste was mostly accurate, it was still inconsistent.

The Outcome:

We determined that the braze joint orientation was not conducive to the use of the paste. Brazing paste is best suited for horizontal joint applications, which is why the customer saw the alloy move out of place. In similar cases, P&I has suggested the use of preforms. Preforms better suit vertical braze joint orientations, thus, avoiding future reworks due to loss of viscosity and movement. An added advantage of a custom, or standard, brazing preform is that the volume can be controlled consistently throughout every application, thus, avoiding any flashing from wetting the surface of the part.

Using a pre-engineered copper preform, the customer could avoid all previous braze paste-related issues and optimize their manufacturing operations. 

Are you experiencing a related issue? If so, contact us to discuss alternatives specific to your needs.