aluminum brazing

The heat treat industry is rich with knowledgeable leaders, resourceful problem solvers, and innovative teams. One of our favorite things to do here at Heat Treat Today is to draw attention to the wealth of expertise in the field, so we are pleased to launch the Voices in Heat Treat series, pointing readers to a treasure house of recorded interviews and discussions diving into the fundamentals of thermal processing.

In this and coming articles drawn from the audio library at Solar Atmospheres, we will summarize topics on everything from basic heat treating how-tos, preventative maintenance, and troubleshooting to the history of hot zone designs, temperature uniformity surveys, and the distinctions to take into consideration when processing different kinds of metals and alloys. In today’s installment, our industry experts focus on vacuum brazing and the uniqueness of heat treating titanium.

In the premiere article of this series, Bill Jones, founder and CEO of Solar Atmospheres and Solar Manufacturing, interviews industry leaders about the advantages of vacuum furnace brazing. Read the highlights of their discussion about the process, in particular when used with stainless steel and titanium. The summary of a fourth episode recorded earlier has been added, expanding on the topic of the advantages of processing titanium in a vacuum furnace. The experts are Calvin Amenheuser, vice president of the Hatfield plant, and Mike Paponetti, sales manager of the southeast. Jim Nagy, senior vice president of Solar Manufacturing, hosts the episodes. A summary of each conversation is below, followed by links that will take you directly to that podcast episode.

Bill Jones and the Team Speak on Vacuum Brazing, a 3-Part Series

“Advantages of Vacuum Furnace Brazing”

December 2015

This episode is the first in a series on vacuum furnace brazing, with an overview of different types of brazing processes and why vacuum furnace brazing is superior to other joining methods, particularly torch brazing and welding.

The conversation explores various reasons why a vacuum furnace is well-suited to perform brazing because it provides:

• a controlled, consistent atmosphere cycle after cycle
• uniform heating throughout the hot zone
• a controlled rate of heating
• the elimination of air to prevent the formation of oxidation of the metal

Vacuum Furnace Brazing vs. Alternative Methods

Both Cal Amenheuser and Mike Paponetti speak about vacuum brazing being a superior process to alternative methods. Mike noted that torch brazing is effective for low volume loads, but the process risks flux entrapment and could produce messy, overheated and possibly carburized parts. In contrast, vacuum furnace brazing allows for higher volume loads, providing a repeatable process, precise temperature measurements, and versatility.

Calvin added that while welding melts the materials and produces a strong joint, the surrounding material is weaker. With vacuum furnace brazing, the brazed joint is just as strong or stronger afterward as before.

Finally, the panelists compared how batch vacuum furnace brazing eliminates distortion that is typical with torch brazing and welding because of hot zone uniformity. A batch furnace operator can modify the process to meet the demand of the load, and furnace charts provide proof of reveal what exactly happened during the run so that successful recipes can be repeated.

Click here to listen to this episode.

“Vacuum Brazing of Stainless Steel”

February 2016

In this episode, second in the series on the vacuum furnace brazing, the Solar team reconvened to discuss advantages of and concerns with nickel-based and copper-based brazing alloys.

All agree that nickel-based alloy offers a cleaner braze but emphasize precautions must be put in place to avoid metal erosion and cracking. While readily available and a good match for low carbon steel, copper flashes during the braze. Inert gas is recommended to decrease evaporation of the copper-based alloy.

Click here to listen to this episode.

“Processing Titanium in Vacuum Furnaces: Active Brazing of Titanium in a Vacuum Furnace”

April 2016

In this third and final episode on the topic of vacuum furnace brazing, Bill Jones, Calvin Amenheuser, and Mike Paponetti consider significant challenges to brazing titanium, which is the need to reduce surface oxide to allow the process to take place and why active brazing is suggested as a means to meet that challenge. What follows is an informative discussion on composites that allow producing companies add to the material, like hydrated titanium, zirconium, and indium, to help overcome oxides, which are effective at wedding to the surface.

Click here to listen to this episode.

Additional Notes on Titanium

“Processing Titanium in Vacuum Furnaces: Advantages”

February 2013

Although recorded earlier than and thus separately from the series on vacuum furnace brazing, this summary of an episode is included in this article to provide context about the advantages of processing titanium in a vacuum furnace. This is a solo Bill Jones episode.

Bill Jones highlights how vacuum furnaces provide a pure atmosphere for processing titanium compared to an argon atmosphere, saving machining costs and time. Additionally, vacuum processing uses forced inert gas quenching to cool titanium as opposed to water quenching which results in a more uniform result and eliminates part distortion. Finally, fixturing parts properly in a vacuum furnace with graphite allows heat treaters to preserve the part shape and avoid movement.

Click here to listen to this episode.

We share these resources from the audio library at Solar Atmospheres.

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