He buscado mucho, pero no encuentro una traducción concreta. La que te he propuesto es simplemente la traducción de la explicación que dan en esta referencia:

Chordal Drop Management (CDM)
Reducing the space between the bit
body and the wall of the hole —
”chordal drop management”—is
imperative to achieving secondary
stability. CDM is accomplished through
various techniques, including increasing
the number of blades, designing
blades with equal junk slots, increasing
blade width and widening gauge pads.
http://www.bakerhughes.com/hcc/literature/products/genesis.p...

A lo mejor alguna de las referencias siguientes te inspiran algo:

Chrodal
Domain Definition
Building & Civil Engineering A transverse structure which lowers the water level along its course.
http://www.websters-online-dictionary.org/definition/drop

Drop
Mining
A. Granulated material obtained by pouring melted material into water b. In the roof of a coal seam, a funnel-shaped downward intrusion of sedimentary rock, usually sandstone. See also:stone intrusio c. The vertical displacement in a downthrow fault; the amount by which the seam is lower on the other side of the fault d. In an air lift, the distance the water level sinks below the static head during pumping e. The small downward descent of the upper section of a drill rod, casing, or pipe into a lower like section when the threads of the box- and pin-threaded parts match, so that upper and lower sections may be screwed together without cross-threading f. The sudden descent of a bit that occurs when a bit encounters a cavity or cuts through a hard rock and enters a very soft rock g. To lower drill-string equipment into a borehole h. To lower the cage to receive or discharge the car when a cage of more than one deck is used i. To allow the upper lift of a seam of coal to fall or drop down. (references)
www.websters-online-dictionary.org/ definition/Spanish-english/index170.html

Drop
Building & Civil Engineering
Spanish English Dictionarydestoconado por perforación · destoconador · destoconadora de disco · destorcedor ... desviación inferior del valor cordal · desviación inferior y superior ...
www.websters-online-dictionary.org/ definition/Spanish-english/index170.html

echnical English - Spanish VocabularyChordal thickness, espesor cordal , ( Ingeniería de diseño ) Espesor tangencia¡ de un diente de un engranaje cilíndrico, medido sobre una cuerda del círculo ...
www.sapiensman.com/ESDictionary/ C/Technical_vocabulary_Spanish(C15-B).htm -

Chordal effect
Mining
The effect produced by the chain joint centers being forced to follow arcsinstead of chords of a sprocket pitch circle. (references)

pt catalog 601-904M Spanish, metric units.qxpFile Format: PDF/Adobe Acrobat
también minimiza los efectos de la acción cordal debido a que el paso se incrementa ... Transmisión Rampower en una bomba de perforación petrolífera ...
www.ramseychain.com/catalogs/pt/pt_spanish_metric.pdf