China
Africa
Explore chapters and articles related to this topic
Blueprint Reading
Published in Frank R. Spellman, The Science of Wind Power, 2022
With the passage of time and corresponding improvements in technology, greater accuracy became possible (measurements in fractions of an inch were no longer exact enough). Smaller parts of an inch were needed and provided by dividing the inch into 1,000 parts, the parts being referred to as “thousandths of an inch.” One-thousandth of an inch is written as .001″. Common measurements of an inch, for example, are expressed as follows: One inch1.000″One-thousandth of an inch.001″One ten-thousandth.0001″One millionth.000001″
Compressed Air Filtration, Lubrication, and Moisture Control
Published in Anton H. Hehn, Fluid Power Troubleshooting, 1995
Pneumatic system pollution is measured using the micrometer scale. One micrometer is equal to one-millionth of a meter or 39-millionths of an inch. A single micrometer is invisible to the naked eye and is so small that even to imagine it is extremely difficult. To make the size more conceivable, two everyday objects measured using the micrometer scale have the following values (see Fig. 5.2): an ordinary grain of table salt measures 100 μm, and the average diameter of human hair measures 70 μm. Twenty-five micrometers is approximately one-thousandth of an inch. The lower limit of visibility for an unaided human eye is 40 μm. In other words, the average person can see dirt that measures 40 μm and larger. Some of the harmful dirt particles of a pneumatic system are below 40 μm in size.
Introduction to Micro- and Nanofabrication
Published in Andrew Sarangan, Nanofabrication, 2016
SI unit has become the accepted standard at many scientific journals and institutions. However, other units of measures are still widely used in laboratories and industry due to their legacy, convenience, and existing tools. For example, “mil” (one thousandth of an inch) is used in many areas of machining to specify material thicknesses and is used even in lithography processes in device fabrication. Thin films are widely measured in Angstroms rather than nanometers. Compressed gas pressures are most commonly measured in pounds per square inch (psi). Gas flows are measured in standard cubic centimeters per second (sccm) or liters per minute (lpm). Vacuum is measured in Torrs in the United States and Pascals or millibars in other parts of the world. Resistivities are measured in Ω-cm. Semiconductor doping is measured in cm−3. Most of these are not SI units. Time is measured on a base 60 system, even by the most ardent proponents of the decimal system. It is the author’s personal view that we should appreciate and respect the standards that have evolved in different areas. Which units are most appropriate should really be left for those doing the actual work in their respective fields. Every engineer and scientist should be comfortable converting between different units. The purpose is to clearly communicate a quantifiable unit of measure, not to make the conversion arithmetic simpler. Most importantly, the minor inconvenience of converting between units should not be the sole reason to force conformity to a single standard. In that spirit, we will use the most commonly used units of measure for each of the areas covered in this book.
Optimal design of a two-point variables skip-lot sampling plan with Taguchi capability index
Published in Quality Engineering, 2023
To illustrate the applicability of the approach proposed in this study, we conducted the plan in the concrete case for resistor manufacturing, presented by Pearn and Wu (2006). The two-sided tolerance limit for one type of resistor is (i.e., the target value is 10 mil). Mil is a unit of length and equals one-thousandth of an inch. The protections for producers and consumers against the lot quality () with f = 1/10 are chosen, and the plan parameters obtained from Table 1 are (n, k, i) = (60, 1.1812, 3). The operation for inspection is described as follows: Lot-by-lot inspection should first be executed. A sample of size 60 is taken at random from each lot and the Anderson-Darling (AD) normality test is required to examine whether the data follow a normal distribution or not. Next, the estimators, e.g., and estimator of were calculated based on the recorded measurements. The lot disposition for the current lot can lastly be addressed.