Materials Matter

The Casting Process for Gears, Part II

White Iron will Normally Contract at 1/4” per Foot. Contraction is not always equi-dimensional, in that it is influenced by mass and configuration. Contraction is...

The Casting Process for Gears, Part I

The advantages of using castings for engineering components such as gears are well appreciated by design engineers. Of major importance is the fact that...

Closed Die Forging

Forging is the process of forming and shaping metals through the use of localized compressive forces.  Forgings are worked above their recrystallization temperature and...

Gear Rating vs. Percent Lower Transformation Products in Steel Gears

Some gear rating specifications, such as the popular the AGMA 2001, require a minimum percentage of lower transformation products (martensite, lower bainite)1  to a...

Nondestructive Testing and What Certification Fits Your Gear Production Needs

Nondestructive testing (NDT) is a fascinating and ever evolving field prevalent within the gear industry. It is because of this evolution that a need...

Grain Size Requirements

For gear material supplied in the intermediate heat treat condition, the capability grain size would be appropriate. The goal is to show (usually on...

Considering As-Heat Treated Grain Size

When reviewing and working to customer steel specifications, it seems to me that one of the most misused and misunderstood gear material requirements is...

Dealing with ‘Ghost Signals’

During my time in the nondestructive testing field, I have experienced one anomaly continually arise while performing specific ultrasonic examinations of forgings. I’m speaking...

Why is the Center in Tension?

Consider that each ring segment has the same volumetric expansion. Next, take the mid-wall circumference and multiply that by the volumetric expansion resulting from...

Determining Transformation Products

Transformational stresses arise from the volumetric expansion of the Face Centered Cubic (FCC) crystal structure to Body Centered Cubic/Tetragonal (BCC/BCT). The degree of volumetric...

Selecting the Best Application Combination

While large heat-treated components will always contain some stress, these stresses can be minimized in order to reduce the likelihood of catastrophic failure while...

Sorting Through the Forging Selection Process

The forging process, one of the oldest methods of metalworking, is often still the best suited for many part applications. Due to upgraded computer...

Powder Metal Gears, Part IX

In Part IV, Macro Design was discussed and a corrugated web was presented. The idea of the corrugated web came from several directions and...

Powder Metal Gears, Part VIII

Another finding demonstrated by Dr. Strehl’s manufacturing simulation was the reduced investment costs for a new gear factory when going the PM route. In...

Powder Metal Gears, Part VII

So far, five powder metal gear related topics have been covered: effects of porosity, noise and NVH, micro design and robustness, macro design and...

Powder Metal Gears, Part VI

The heat treatment issue discussed in previous columns remains for the rollforming as well; low-pressure carburization helps, due to a better process when introducing...

Powder Metal Gears, Part V

So far we covered porosity of powder metal and some of its effects: Noise and NVH, macro design and reduced weight, and micro design...

Powder Metal Gears, Part IV

In the previous article, the micro design, in the sense of profile modifications to the teeth, was discussed. This fourth article will deal with...

Powder Metal Gears, Part III

Since the Young’s modulus and Poisson’s number are density-related, it is important to use the PM relevant numbers in the design phase of the...

Powder Metal Gears, Part II

NVH is one of the most difficult areas of gearing approaching black art. Transmission developers have their own standards for testing. Often subjective measurements...
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