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Search Publications by: Jon R. Pratt (Fed)

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Displaying 176 - 200 of 230

Probe-Force Calibration Experiments Using the NIST Electrostatic Force Balance

January 1, 2003
Author(s)
Jon R. Pratt, David B. Newell, John A. Kramar, J Mulholland, Eric P. Whitenton
The sensitivity of a piezoresistive cantilever force sensor has been determined by probing the weighing pan of the NIST prototype electrostatic force balance. In this experiment, micronewton contact forces between a force probe and the balance''s weighing

Compact Force Sensors for Low-Force Mechanical Probe Calibration

September 1, 2002
Author(s)
Jon R. Pratt, Douglas T. Smith, S Woody
The loading mechanisms of instrumented indentation machines are often calibrated using deadweights. In many cases, due to the geometry of the loading frame, the applied deadweight is tensile, while the indentation leads to be measured are compressive. In

Compact Force Sensors for Low-Force Mechanical Probe Calibration

June 1, 2002
Author(s)
Douglas T. Smith, S Woody, Jon R. Pratt
The loading mechanisms of instrumented indentation machines are often calibrated using deadweights. In many cases, due to the geometry of the loading frame, the applied deadweight is tensile, while the indentation leads to be measured are compressive. In

The NIST Microforce Realization and Measurement Project

June 1, 2002
Author(s)
David B. Newell, Jon R. Pratt, John A. Kramar, Douglas T. Smith, Edwin R. Williams
The National Institute of Standards and Technology (NIST) has launched a five-year Microforce Realization and Measurement project focusing on the development of an instrument and laboratory capable of realizing and measuring the SI unit of force below

The NIST Microforce Realization and Measurement Project

June 1, 2002
Author(s)
David B. Newell, Jon R. Pratt, John A. Kramar, Douglas T. Smith, Edwin R. Williams
The National Institute of Standards and Technology (NIST) has launched a five-year Micro-force Realization and Measurement project focusing on the development of an instrument and laboratory capable of realizing and measuring the SI unit of force below

Regenerative Stability Analysis of Highly Interrupted Machining

May 1, 2002
Author(s)
Matthew A. Davies, Jon R. Pratt, Brian S. Dutterer, Timothy J. Burns
We discuss theoretical and experimental work that supports the use of very low radia immersion in the high-speed milling of difficult-to-machine materials, such as titanium alloys. Our theory is based upon modeling the cutting process by a kicked harmonic

Stability Prediction For Low Radial Immersion Milling

May 1, 2002
Author(s)
Matthew A. Davies, Jon R. Pratt, Brian S. Dutterer, Timothy J. Burns
Traditional regenerative stability theory predicts a set of optimally stable spindle speeds at integer fractions of the national frequency of the most flexible mode of the system. The assumptions of this theory become invalid for highly interrupted

NIST Electrostatic Force Balance Experiment

January 1, 2002
Author(s)
John A. Kramar, David B. Newell, Jon R. Pratt
We have designed and built a prototype electrostatic force balance for realizing forces in the micronewton range. The active electrodes are concentric cylinders, the outer serving as the reference and the inner suspended and guided by a rectilinear flexure

SI Traceability of Force at the Nanonewton Level

July 1, 2001
Author(s)
David B. Newell, Jon R. Pratt, John A. Kramar, Douglas T. Smith, L. A. Feeney, Edwin R. Williams
Although nanonewton force measurements are commonplace in industry, no National Measurement Institute supports a link to the International System of Units (SI) below one newton. The National Institute of Standards and Technology has launched a five-year

A New Stable Speed Test Apparatus for Milling

May 1, 2001
Author(s)
J P. Snyder, Jon R. Pratt, Matthew A. Davies, S J. Smith
This paper describes a new device that uses a non-contact force actuator in conjunction with spindle rotation to produce an impulsive periodic driving force on the tool at the tooth passing frequency. Measurements are made of the applied and of the