One Year Anniversary For Aero Gear Vacuum Carburizing Furnace

A little over one year ago, Aero Gear purchased a new – and very yellow – vacuum carburizing furnace in order to gain more control over case depth, hardness, and distortion compared to traditional atmosphere carburizing. Unlike atmosphere carburizing, our new furnace operates at pressures near the 1 micron range (that is 99.9999% of a perfect vacuum). What makes this technology so exciting is the ability to precisely control heat treatment parameters, and since its arrival in the beginning of July 2013, our team of engineers has been developing processes which remain consistent and repeatable. As a matter of fact, we have carburized nearly 6,000 pieces without a single metallurgical rejection.

Comparing Atmosphere and Vacuum Carburizing Results

Most of our precision gears are made out of the industry standard AISI 9310 and Pyrowear 53 steels. These low carbon steels were designed to be carburized in atmosphere furnaces, but we have seen that they vacuum carburize with more uniform case depth and hardness. The ability to drive carbon deeper into the surface also enables the gear to have much higher case hardness and compressive stresses which signify a stronger, tougher part. In addition, higher case hardness increases wear and pitting resistance.  To prove the merits of vacuum carburizing, we performed a residual stress profile using x-ray diffraction on as-carburized samples of a gear made of AISI 9310 steel. The results are below:

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Residual compressive stress in the case is 19% greater at the flank and 1260 MPa in the root when comparing vacuum vs. atmosphere carburized samples. Surface hardness for the atmosphere carburized sample is 62 HRC (Flank), 59 HRC (Root). Surface hardness for the vacuum carburized sample is 64 HRC (Flank), 62 HRC (Root).

Predictable Distortion

One of the key reasons Aero Gear has invested in vacuum carburization is more distortion control. The distortion can be very detrimental to a gear, regardless of how robust the carburizing process may be. Tooth spacing error, for instance, can lead to uneven grinding and the risk of removing too much case from one side of the tooth than the other. We use our on-site CMM (Coordinate Measuring Machine) to inspect all features of a gear, and using this data our engineers can tailor processes and fixturing on an individual part number basis. Parts carburized in our vacuum furnace distort less and have better case uniformity throughout the gear with more predictability.

Future Development

The addition of the vacuum furnace has allowed us to work on the development of heat treatment of new materials with our customers such as Ferrium C64. Aero Gear is currently developing heat treating and machining processes for Ferrium C64. This new material developed by Questek Innovations uses an M2C carbide precipitate to achieve hardness (where M is metal; C is carbon). Unlike AISI 9310 and Pyrowear 53, which use an epsilon carbide, the M2C carbide is much more effective and requires less carbon to achieve hardness. Precise carbon and temperature control is required for Ferrium C64 in order to avoid complex carbide (M6C, M7C3, M23C6, etc.) formation which could lead to crack propagation and reduced toughness during operation. Aero Gear’s engineers have developed processes to achieve optimum hardness and core properties while maintaining a carbide free microstructure. In addition, we have been developing machining processes to deal with the increased core hardness of Ferrium C64. Due to the significant amount of alloying constituents, machining parameters must be changed in order to compensate for the increased hardness and toughness. Furthermore, the capability to 2-bar quench allows us to reduce distortion, reducing machining time during further processing.

Furnace Photo Sphere

We are continually learning and advancing our ability to successfully heat treat and machine complex geometries. We have accomplished so much more than we expected with our vacuum furnace but we still have so much more to develop and learn. Our expectations for the next year are even greater than last. We are on a path to be the experts in manufacturing vacuum carburized/hardened ground gears in the aerospace industry.

Look for our next update in the near future!


Aero Gear Featured in Journal Inquirer Farnborough Air Show Article

“This is a very global industry,” Rose said of the aerospace business. “And you need to have global exposure to make it work.”

Our very own Doug Rose was recently interviewed for an article in the Journal Inquirer!  Doug, along with other leaders in the CT aerospace industry, discuss the importance of attending the international shows, and how the Department of Economic and Community Development is making it possible.


State’s Small Aerospace Companies Gain Contacts, Exports at Air Show

By Howard French Journal Inquirer

Connecticut’s big aerospace companies, like Pratt & Whitney and Sikorsky, weren’t the only ones to make the trip to England’s Farnborough International Air Show.

Connecticut’s smaller aerospace suppliers — including AdChem Manufacturing Technologies Inc. of Manchester, Aero Gear Inc. of Windsor, and Flanagan Industries of Glastonbury — also seized the chance to spotlight their products and capabilities on the world stage.

Aero Gear President Douglas Rose said Thursday the trip was more about making new contacts and seeing existing overseas customers than signing contracts.

“This is a very global industry,” Rose said of the aerospace business. “And you need to have global exposure to make it work.”

Rose said the state Department of Economic and Community Development’s work on behalf of smaller companies trying to achieve a global profile is invaluable.

“We would not be able to do this on our own,” he said of making a mark at major air shows like England’s Farnborough or the Paris Air Show.

Ten years ago, he said, his company was doing little or no business overseas. “Now about one-third of our business is in exports,” Rose said.

DECD Deputy Commissioner Ronald Angelo said Aero Gear’s success from the state’s program is exactly what the agency has been aiming for in the nine years the program has existed.

“This year was a real leap forward,” Angelo said Thursday. He explained that after years of taking groups of smaller aerospace companies to international air shows, foreign-based companies have begun to recognize Connecticut as a prime source of high-quality aerospace products.

“We have major companies walking into our booth now,” he said of the growing recognition of the state’s aerospace industry.

The state has nearly 1,000 smaller aerospace suppliers, Angelo said. If growth spurred by participation in global air shows results in the hiring of two or three workers at each company, he said, that adds up.

Flanagan Industries Co-owner and Vice President Kevin Flanagan also said the state’s effort to boost the smaller companies has been a major success.

“Around the world now, Connecticut is being recognized as ‘aerospace alley,’” he said, which is giving businesses like his a major boost.

Although his plant employs only about 100 people, Flanagan said he’s been able, through the state program, to make contacts around the world. At the Farnborough show, for example, he met with Asian companies for the first time and expects as a result to be visiting one Japanese company this fall to talk about future business.

Like Aero Gear’s Rose, Flanagan said that when he started eight years ago with the Connecticut program, he was doing almost no export business. Now it’s at least 6 percent of his business.

AdChem President Michael Polo said his company signed agreements at Farnborough that should result in three new contracts.

One of the biggest advantages of the’s state’s effort to bring businesses like his to the air show, Polo said, is the number of major manufacturers in one place.

“They’re all there,” he said, making it possible to get orders and leads that otherwise would have required extensive and expensive individual travel.

Polo said U.S. export restrictions such as the International Traffic in Arms Regulations, or ITAR, make exports difficult and lead smaller companies, including his, to consider establishing a facility overseas to make it easier to do business.

Still, he said, his company, which has about 50 employees in total, is preparing to add more workers locally as business continues to grow.

This year the state’s smaller aerospace companies at Farnborough were in a Connecticut pavilion, part of the state’s Airshow Exhibit Program, administered by the DECD in partnership with the Connecticut Center for Advanced Technology Inc.

Overall, Connecticut companies have reported more than $300 million in sales generated from show participation, according to DECD statistics.