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Kay & Associates Brazing Quiz

For this month’s column we would like to challenge our readers to have some fun with a brazing quiz. If you would like to try our Brazing Quiz, please e-mail your responses to This email address is being protected from spambots. You need JavaScript enabled to view it., listing the numbers 1 through 20 and your correct “letter” response next to each number. The correct answers (with explanation) will be printed in next month’s (May) article.

Last Updated on Saturday, 17 June 2017 03:11

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Essential Criteria for Brazing: Item 4 – Proper Choice of Brazing Filler Metal (BFM)

We look now at the fourth of the seven important criteria that should be followed in order to insure good brazing, namely, the proper choice of a brazing filler metal (BFM) to use for your application.  You’ll find that you have a number of possible options from which to choose, but always bear in mind that the end-use application should always be the deciding factor when trying to decide on which BFM will be best for your current needs.

There are many different brazing filler metal (BFM) families, and so, for easier identification, an orderly arrangement, such as that shown in the American Welding Society’s A5.8 Specification for BFMs in Fig. 1 helps to categorize these many alloys into groups that are more meaningful.

Essential Criteria for Brazing: Item 3b – Proper joint fit-up and Surface Roughness concerns

Essential Criteria for Brazing: Item 3b – Proper joint fit-up and Surface Roughness concerns

In recent months we have been examining the essential criteria for good brazing, many of which are, unfortunately, overlooked by designers and brazing personnel, thus causing problems in production. We are currently looking at critical issues related to proper joint fit-up, and one of these issues concerns the finish (roughness) of the faying surfaces inside a braze-joint. Surface roughness can range from highly-polished to very rough, and can, in fact, have a significant effect on the ability of molten brazing filler metal (BFM) to flow into and through a braze-joint. As shown in Fig. 1, some brazing personnel have resorted to a variety of ways to roughen surfaces for brazing so that, in their opinion, the molten brazing filler metal (BFM) can “flow better”. This can be quite misleading, since good brazing depends primarily on proper joint design, proper cleanliness of the parts, and joint-gaps that are quite thin, three criteria that have been discussed in my prior articles in this series.

Essential Criteria for Brazing: Item 3 – Proper joint fit-up

In honor of the one hundred anniversary of its discovery, thermal spraying looks back to its roots – early experiments in which liquids were broken up into fine particles by a stream of high-pressure gas. Efforts more directed at producing powders rather than constructing coatings. It fell to one Dr. Max Ulrick Schoop of Zurich who recognized the possibility that a stream of molten particles impinging upon themselves could create a coating.

Schoop ‘swork, and that of his collaborators, resulted in the establishment of the thermal spray process. This process has fostered a worldwide industry serving over thirty technology sectors and generating sales of over two billion dollars per year. This article traces the history and development of the principal flame and electrical thermal spray processes. and that of his collaborators, resulted in the establishment of the thermal spray process. This process has fostered a worldwide industry serving over thirty technology sectors and generating sales of over two billion dollars per year. This article traces the history and development of the principal flame and electrical thermal spray processes

Last Updated on Monday, 16 January 2017 16:15

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Essential Criteria for Brazing: Item 2 – Proper cleaning—role of tumble deburring in surface-prep (Part D)

As shown in my last four articles, there are a number of very important steps that must be followed in order to insure good brazing, as shown here once again in Table 1. We’ve looked at some proper design criteria for brazing, and the last three articles have covered some important aspects of cleanliness in brazing. In this current article we will explore tumble-deburring as an excellent method to use to prepare surfaces prior to their being assembled for subsequent brazing, but with some strong precautions.

Tumble-deburring surfaces involves placing a number of parts in a special container and then causing those parts to literally “tumble” many times onto each other, or within a special media (for gentler tumbling) so that any burrs on the edges of each part can be removed prior to those parts being subsequently assembled for brazing. Tumble-deburring equipment usually is of two types, either a container that can be closed and then tumbled over and over on a rack such as shown in Fig. 1, or the deburring can be done in an open container (with rounded inner walls) which is then vibrated (agitated) causing the parts to move up the rounded walls of the container and then fall back into the tumbler.

Essential Criteria for Brazing: Item 2 - Proper cleaning—role of grit blasting in surface-prep (Part C)

As shown in my last three articles, there are a number of very important steps that must be followed in order to insure good brazing, as shown here once again in Table 1. We’ve looked at some proper design criteria for brazing, and the last two articles have covered some important aspects of cleanliness in brazing. In this current article we will explore grit blasting and tumble-deburring as common methods many companies use to prepare surfaces prior to their being assembled for subsequent brazing.

Grit blasting surfaces involves placing parts in a special chamber, as shown in Fig. 1, and then using a high-pressure stream of hard particles being blasted at the surface of the part in order to remove certain surface contaminants, such as surface oxides, that would otherwise interfere with good brazing, i.e., would prevent the molten brazing filler metal (BFM) from being able to effectively alloy with, and bond to, the base metals onto which it is being applied.

Essential Criteria for Brazing: Item 2 — Proper Cleaning/handling means wearing gloves (Part B)

As shown in my last two articles, there are a number of very important steps that must be followed in order to insure good brazing, as shown here once again in Table 1. We’ve looked at some proper design criteria for brazing, and last month we began looking at the very important topic of cleanliness in brazing..

As we saw, parts must be clean BEFORE they are brazed, and part of that cleanness-issue, as we will examine in this month’s column, involves the handling of parts during assembly and the application of brazing filler metal (BFM) to those parts. It’s at this point that many shops fail in their understanding of what it takes to keep parts clean prior to brazing. Namely, bare hands are too often used to assemble parts, resulting in contamination of surfaces that are to be brazed. Let’s take a closer look at the role of the cleanliness of the brazer’s hands and how to prevent contamination of the parts by the brazing personnel themselves.

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