brazing - aws c3.7

If you are just starting in the aluminum brazing business, or have been brazing proprietary products to internal brazing specification and want to expand into contract brazing we can help you save time and money in this effort.

The process of determining exactly what requirements need to be satisfied and best way from a cost and process position to implement them can be daunting. We can help guide you through the process and assist with the procedures and training necessary to maintain compliance and pass customer audits.

The brazing work flow chart at left will give you a general concept of the operational flow of a brazed assembly. Click on the flowchart for a larger version. Not all assembly types require all operations, for example there may not be final machining on a specific brazed assembly. Others may have additional operations such as VSWR testing of waveguides, leak or pressure drop testing for heat exchangers and coldplates.

Historically, there have been many different brazing specification used for aluminum brazing. Most were Military Specifications and through the years many were cancelled and superseded by MIL-B-7883. Two different versions of this specification coexisted as MIL-B-7883B and MIL-B007883C. They did have some problems from a user’s point of view, but were largely accepted and used successfully for many years. They were cancelled 1996 replaced with the American Welding Society AWS C3.7 for Flux and Controlled-atmosphere brazing of aluminum. This does not mean that all the existing drawings which still call out the MIL-B-7883 must meet the requirements of AWS C3.7. Processing and certifying to the Mil Spec is allowable, and most times preferable to the AWS C3.7.

From 1996 on, most new brazed assembly designs use AWS C3.7. The most recent version of this is AWS C3.7M/C3.7:2011 and supersedes the prior 2005 version. Although this 2011 version is an improvement over prior versions, many of the same issues remain from a user’s view point. Living up to all the specific requirements of this specification is a very difficult and costly process, and at times not practical. We can help you avoid the costly traps of this specification prior to your customer’s order so that your certifications truly reflect your process.

For additional information on the aluminum braze process the Aluminum Association produced the Aluminum Brazing Handbook and the American Welding Society produces a Brazing Handbook. Click on the association names for a link to their respective sites and search for Brazing Handbook.