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JIS B 7420 is the Japanese Industrial Standard for Plain Limit Gauges, providing critical requirements for the design and manufacturing of gauges used to check hole and shaft tolerances in mechanical engineering. Overview of JIS B 7420
The standard focuses on "Go" and "No-Go" gauges, which are used to determine if a part’s dimensions fall within a specified tolerance without providing an actual measurement value.
Scope: Covers types, shapes, dimensions, and tolerances of limit gauges for holes and shafts.
Key Identification: The standard defines how to distinguish between gauge ends. For example, the NOT GO gauge is typically shorter than the GO gauge and may be marked with a red ring or a specific groove.
International Alignment: It is closely related to international standards like ISO/DIS 1938-1, ensuring technical consistency across global manufacturing. Critical Technical Specifications
According to NormSplash and PhysicsNorm, the standard details several complex aspects of gauge management:
Permissible Wear: A major part of the document defines "permissible wear within hole tolerance" and "permissible wear within shaft tolerance." This allows for a small amount of material to wear away from the gauge over time while still maintaining the integrity of the inspection.
Gauge Proportions: The length of the "GO" portion of a plug or ring gauge must be equal to the length of the feature being inspected to ensure full-form verification.
Form Tolerances: Beyond simple diameter, the standard sets limits on form deviations (like roundness or taper) to ensure the gauge itself doesn't introduce measurement errors. Application & Selection
When applying JIS B 7420 in a production environment, manufacturers typically follow these guidelines for ordering or fabricating:
Tolerance Grade: Gauges are selected based on the specific tolerance grade of the hole or shaft being inspected (e.g., H7, g6).
Special Materials: While standard gauges are common, high-wear versions (like carbide or ceramic) are often requested for high-volume production to minimize the frequency of re-calibration.
Maintenance: Regular inspection of gauges is necessary to ensure they haven't worn beyond the "permissible wear" limits established by the standard.
For a deep dive into specific dimensions and tables, you can view the sample excerpt of JIS B 7420:1997 here or purchase the full 52-page standard through providers like Afnor EDITIONS. JIS-B-7420-1997-en.pdf - NormSplash
Introduction
JIS B 7420 is a widely recognized standard in Japan and internationally, outlining the requirements for the calibration and verification of non-automatic weighing instruments, including balances, scales, and weighing machines. The standard aims to ensure the accuracy and reliability of weighing instruments used in various industries, such as commerce, manufacturing, and healthcare. jis b 7420 pdf
Scope and Application
JIS B 7420 applies to non-automatic weighing instruments used for measuring the mass of objects, including:
The standard covers the calibration, verification, and testing of these instruments to ensure they meet the required accuracy and performance standards.
Key Requirements
The JIS B 7420 standard outlines several key requirements for the calibration and verification of non-automatic weighing instruments, including:
Benefits and Importance
The JIS B 7420 standard offers several benefits, including:
PDF Availability
The JIS B 7420 standard is available in PDF format from various sources, including:
It is essential to ensure that the PDF version of the standard is obtained from a reputable source to guarantee its authenticity and accuracy.
In conclusion, JIS B 7420 is a critical standard for ensuring the accuracy and reliability of non-automatic weighing instruments. Its guidelines and requirements help organizations maintain compliance with regulatory requirements, improve efficiency, and reduce errors.
The JIS B 7420:1997 is the Japanese Industrial Standard for Plain Limit Gauges, which are tools used to inspect the dimensional accuracy of holes and shafts without a scale. It provides the specifications for design, tolerance, and application of "Go" and "No-Go" gauges for workpieces up to 500 mm in diameter. Scope and Purpose
Dimensional Inspection: Used for checking holes and shafts to ensure they meet specified tolerance grades.
Tolerance Grades: Specifically applies to tolerances IT6 to IT16 as defined in JIS B 0401.
Size Limit: Applicable for nominal sizes not exceeding 500 mm. Standardized Gauge Types JIS B 7420 is the Japanese Industrial Standard
JIS B 7420 covers several standard gauge forms used for rapid quality control on production lines:
Plug Gauges: Cylindrical gauges used for inspecting internal hole diameters.
Ring Gauges: Circular gauges used to check the outside diameter of shafts.
Gap (Snap) Gauges: U-shaped frames with jaws used to check the accuracy of external dimensions like shafts or male members.
Reference Disks: Used specifically for calibrating or setting gap gauges. Key Specifications
Material: Typically made from tool steel such as SKS31 with a hardness of 58–64 HRC to ensure wear resistance during repetitive use. Gauging Principle:
GO Gauge: Checks the Maximum Material Condition (MMC). It must pass through or over the workpiece.
NO-GO Gauge: Checks the Least Material Condition (LMC). It must not pass through or over the workpiece.
Tolerance Zones: The standard defines the correlation between the tolerance zone of the limit gauge and the tolerance of the workpiece, which varies based on whether the nominal size is above or below 180 mm. Where to Access
Official copies of the JIS B 7420 standard in PDF format can be obtained from recognized standards distributors: JIS-B-7420-1997-1.pdf - PhysicsNorm
JIS B 7420 is the Japanese Industrial Standard for Plain Limit Gauges. This standard specifies the design, dimensions, and tolerances for gauges used to check the dimensional limits of cylindrical workpieces (shafts and holes). Key Technical Aspects
Purpose: It defines the "Go" and "No-Go" gauging principles. The "Go" gauge must fit the workpiece to ensure it doesn't exceed the maximum material limit, while the "No-Go" gauge must not fit to ensure the minimum material limit isn't breached .
Standardization: It provides uniform specifications for gauge manufacturing, ensuring that inspections are consistent across different manufacturing facilities using Japanese standards.
Last Revision: The current widely referenced version was published in 1997 by the Japanese Standards Association (JSA). Where to Access the PDF
Official copies of the PDF are typically behind a paywall due to copyright. You can find the document through these authorized distributors: Balances and scales used in commercial transactions Weighing
Japanese Standards Association: The primary source for JIS Standards.
Technical Standards Store: Offers the JIS B 7420 PDF for digital download .
ANSI Webstore: A common resource for international technical standards . JIS B 7420 PDF - Technical Standards Store
The JIS B 7420:1997 standard, titled "Plain limit gauges," provides the technical specifications for gauges used to inspect holes and shafts with diameters up to 500 mm. Core Technical Content
According to the JIS B 7420:1997 official preview, the paper covers:
Gauge Types: Specifications for plain plug gauges, ring gauges, and snap gauges (gap gauges).
Design Principles: It follows the Taylor Principle, where "GO" gauges check the maximum material limit and "NOT GO" gauges check the minimum material limit.
Tolerance Grades: Applicable to tolerance grades IT6 to IT16 as defined in JIS B 0401.
Wear Allowance: Defines the permissible wear limits for gauges to ensure they remain accurate over time. Helpful Resources & PDF Access
You can find detailed summaries or purchase the full PDF through these platforms:
Standard Previews: Free technical samples showing symbols and definitions are available on PhysicsNorm and NormSplash.
Detailed Overviews: Scribd hosts community-uploaded versions that detail symbols and hole/shaft tolerance tables.
Official Purchase: The complete, authoritative document is available for download at the Japanese Standards Association (JSA) Webdesk or through retailers like ANSI Webstore. Related Standards If you are working with threaded parts, you may also need: JIS-B-7420-1997-en.pdf - NormSplash
Some technical universities and large manufacturing firms maintain subscriptions to standards databases like IHS Markit or Techstreet, which include JIS B 7420.
For detailed information, including specific methodologies and requirements, one would typically need to obtain a copy of the standard. The PDF version of JIS B 7420 can be acquired through various channels:
Yes, if you manufacture measuring equipment or use surface plates for legal metrology (trade, safety, or health). For general workshop use, it is a recommended best practice.
Once you have obtained the legitimate PDF, here is how to integrate it effectively: