Telecurso 2000 - Metrologia - 02 Medidas e Conversões

Summary

This video lesson explores the English system of measurement, particularly focusing on inches and their conversions to millimeters, which are widely used in mechanical engineering. It explains the historical background of the yard and its evolution, alongside how inches are divided into fractions and decimals. Practical conversion techniques between imperial and metric units are demonstrated, along with examples of converting fractional, decimal, and thousandths of an inch to millimeters. The lesson also touches on the importance of precision in metrology, highlighting various tools and methods to ensure accuracy in industrial applications.

Takeaways

• 😀 The inch and millimeter are the most commonly used units of measurement in the metalworking industry.
• 😀 The inch is part of the imperial system, still widely used in the United States, the UK, and Brazil due to the influence of foreign companies.
• 😀 The yard, a unit in the imperial system, was originally defined as the distance from the king's nose to the tip of his outstretched thumb.
• 😀 The yard was standardized in 1959 to 91.44 cm, and other units like the foot and inch were legally defined through royal decrees.
• 😀 Fractions of an inch (like 1/8, 1/16, etc.) are common in measurements but can complicate calculations in the industry due to their imprecision.
• 😀 The decimal inch system was created to simplify these calculations by subdividing the inch into thousandths or millionths (microinch).
• 😀 The decimal inch uses a point instead of a comma, with values such as 0.001 inches or 1 microinch representing thousandths and millionths of an inch.
• 😀 Conversions between inches and millimeters often require multiplying by 25.4 (since 1 inch equals 25.4 mm).
• 😀 To convert millimeters to fractional inches, divide the millimeter value by 25.4 and express the result as a fraction with 128 as the denominator.
• 😀 Practical tips for conversions include using the value 5.04 for simplifying the conversion from millimeters to fractional inches by multiplying the millimeter value by this constant and dividing by 128.

Q & A

What is the purpose of converting units from inches to millimeters in the video?

The purpose of converting units from inches to millimeters is to make measurements easier and more precise for use in mechanical work, as millimeters are more commonly used in industries like metalworking.

Why are inches and millimeters the most common units in mechanical engineering?

Inches and millimeters are the most common units in mechanical engineering because they are the most widely used in the metalworking industry, especially with international companies operating in various countries, including Brazil.

What is the origin of the yard as a unit of measurement in the English system?

The yard originated from the length of the yardstick used by English tailors in medieval times. It was officially standardized in the 12th century by King Henry I, defined as the distance from the tip of his nose to the end of his outstretched thumb.

What does the term 'mile' represent in the English measurement system?

In the English system, a mile is equivalent to 1,760 yards, where each yard consists of 3 feet, and each foot contains 12 inches.

How are fractional inches typically divided in mechanical measurements?

Fractional inches are commonly divided into smaller fractions, such as 1/4, 1/8, 1/16, and so on. These divisions are used to express precise measurements, though they can be cumbersome for calculations.

What is the significance of using decimal inches in industrial applications?

Decimal inches are used in industrial applications because they are easier to calculate and provide more precision compared to fractional inches, which can be complicated and imprecise.

What is a micromile or microinch, and how is it represented?

A micromile, or microinch, refers to a very fine measurement of an inch, represented as a millionth of an inch. It is used in high-precision measurements and is denoted by the term 'microinches' in English.

What are the key steps in converting fractional inches to millimeters?

To convert fractional inches to millimeters, you first multiply the number of inches by 25.4, which is the conversion factor between inches and millimeters.

How do you convert millimeters to fractional inches?

To convert millimeters to fractional inches, divide the value in millimeters by 25.4 and then express the result as a fraction with a denominator of 128. Simplify the fraction to get the nearest inch fraction.

Why is it important to understand the equivalency between different measurement systems in mechanical work?

Understanding the equivalency between different measurement systems, like the metric system and the English system, is essential in mechanical work because it ensures accuracy in manufacturing, designing, and maintaining machinery, particularly in industries with international operations.