Tech in Focus - Steel

 

The rapid development of consumer electronics is very observable. However, steel looks about the same as it always has looked. Yet, a well-known bearing manufacturer states that comparing steel made in the 1970s to steel made today, is like comparing a punch-card computer with a laptop. That is certainly quite a difference.

A number of key technologies have increased the cleanliness of steel dramatically. These include computer-controlled processes, vacuum degassing, argon shrouding of molten steel, and inductive stirring during secondary steel. Component- forming operations, such as open die forging, also need to be on par with the molten steel processes. Accurate temperature control of the hot forming processes, together with complex heat treatment cycles and state-of-the-art knowledge of the material strain during hot forming, are the foundations for further refining the mechanical properties and cleanliness of the steel. 

The quality of the modern European steel, that ATA Gears utilizes, is extremely consistent. In fact, the steel is so clean, that standard inclusion rating methods are becoming obsolete. The distribution of critically sized inclusions is so low, at a certain volume, that nothing can be detected with the blue fracture or step down methods developed in the 1960s or 1970s. In addition, some studies show that conventional statistical micro cleanliness ratings are typically so low that they no longer correlate to laboratory fatigue testing results. The critically sized inclusions, which might cause failures, are not detectable by statistical methods and even are too small to be detected by conventional ultrasonic methods.

ATA may not be an expert in steel making, but with decades of experience – ATA has a solid understanding on what metallurgical properties are crucial for bevel gears that are built to handle extreme loads for twenty years or more. However, in order to evolve, it is not enough to know that something works, but you also need to find out why it works.

ATA has kept learning over time and has been involved in numerous joint industry research projects (JIP) and also carried out a fair bit of research of our own. In the recent years, ATA has studied the effects of material properties and gear geometry on the case hardening process intensively. Acting as a consultant to customers having trouble with gear failures provides great mutual benefits to each party. Often the root causes can be identified and it is rarely a single factor that has caused the trouble. Continuous improvement in steel making technology and close collaboration with material suppliers and customers, make gear failures due to material defects alone extremely rare nowadays.

The improved metallurgy can be utilized either by increasing the power density of a gearbox or by just having extra safety factor (by reducing material failure probability). The question is, however, what is the actual fatigue strength of the currently available 18CrNiMo7-6 grades, for example?

In thinking of the challenges with steels for gear components, the reality is that there is an array of factors to be considered besides just performance. The cost and availability of the material is extremely critical in today’s world. Naturally everyone understands that super expensive, triple vacuum re-melted, high nickel carburizing steel, that has a delivery time of one year, might offer the best performance in terms of fatigue strength.

But, nonetheless, if the carburizing quality or depth is not sufficient or the gearbox design is flawed, the gears may not last no matter how expensive (or fancy) they are. Thus, the key is to understand how gear design (gear geometry), selected material grade and determined carburizing data, work together – not only at the engineer’s desk, but in real manufacturing conditions too. That’s what ATA aims to do.

Tami Komssi ATA

Tami Komssi, Ata Gears, Manager of Thermal Process Technology

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ATA Gears Headquarters / Tampere Finland

P.O. BOX 120
FI-33101 Tampere, Finland
Finnish Company ID: 01538267
Street/delivery address:
Aitolahdentie 75
33580 Tampere, Finland

Telephone: +358 3 2870 111
Telefax: +358 3 2870 249
E-mail: postmaster@atagears.fi

Austria

Mr. Werner Wallenstein

Arberweg 6
D-82536 Geretsried
Germany

Telephone: + 49-8171-5782
Telefax: + 49-8171-31253
Email: w.wallenstein@wdwa.de

China

Mr. Steven Lee

Rm469, 1-building, No. 10 Xinghuo Road
Science City, Fengtai district
Beijing 100070
P.R. China

Telephone: + 86 10 51298290
Mobile: + 86 13601298790
Telefax: + 86 10 65702114
Email: xinzhilee@163.com

Germany

Mr. Werner Wallenstein

Arberweg 6
D-82536 Geretsried
Germany

Telephone: + 49-8171-5782
Telefax: + 49-8171-31253
Email: w.wallenstein@wdwa.de

Italy

Mr. Andrea Schenone

Via Tortona 31
20144 Milano
Italy

Telephone: + 39 02 489 50225
Telefax: + 39 02 489 54103
Email: andrea.schenone@intertec.it

Japan

Mr. Takafumi Nakaoka

Meiji Yasuda Life Osaka Umeda Building
3-3-20 Umeda
Kita-ku
Osaka 530-0001
Japan

Telephone: + 81-6-4795-8820
Telefax: + 81-6-4795-8839
Email: takafumi.nakaoka@tsubaki.co.jp

Korea

Mr. Jae - Hong Huh

Room 119
429, Bongeunsa-ro, Gangnam-gu
Seoul 06087
Republic of Korea

Telephone: + 82-2-2135-3192
Telefax: + 82-2-2007-0337
Email: vasantking1@naver.com

Spain

Mr. Hannu Vainio

C/Azalea, 88-3-1
28109 Alcobendas, Madrid
Spain

Telephone: +34 91 6622923 / +34 91 6622928
Telefax: +34 91 6622928
Email: hvainio@adecorcons.com

Switzerland

Mr. Werner Wallenstein

Arberweg 6
D-82536 Geretsried
Germany

Telephone: + 49-8171-5782
Telefax: + 49-8171-31253
Email: w.wallenstein@wdwa.de

USA

303 E. Central Ave.
Moorestown
New Jersey 08057

Telephone: + 1-856 235-2079
Telefax: + 1-856-273-8740
E-mail: postmaster@atagears.fi

USA

P.O. Box 774
Lenox
Massachusetts 01240

Telephone: + 1-413-637-4490
Telefax: + 1-413-637-4465
E-mail: skkelsmfg@msn.com

USA

500 South Portland Street
Seattle
Washington 98108

Telephone: + 1-206-762-3333
Telefax: + 1-206-762-3704
E-mail: sramberg@thegearworks.com

Canada

724 Middleton Crescent
Milton, Ontario
Canada, L9T 3K8

Cell: 315-415-6853
Fax: 603-643-7166
Email: cronkite@dreamscape.com

China

Rm520, No.7,
Lane 191 Baoxiang Road,
Shanghai 201802, China

Telephone: +86 21 69921736
Mobile: +86 13801729748
Telefax: +86 21 69921736
Email: tommy_au@shanghainordic.com
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