What Are ISO, JIS, DIN, and ASME?
- 翰君 陳
- 4 days ago
- 5 min read
The Essential Beginner’s Guide to Global Fastener Standards
The reason hardware parts can be used, replaced, and serviced across machines worldwide comes down to one thing: standards.
There are many standards in the world, but in fasteners and mechanical parts, you’ll most often run into these four: ISO, JIS, DIN, and ASME.
This article will walk you through the origin, differences, and use cases of these four major standards in a clear and practical way, so that choosing, purchasing, or maintaining parts becomes much less confusing.
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1. Why Do Hardware Components Need Standards?
Screws, nuts, washers, retaining rings, dowel pins… all of these are mating parts.Without common standards:
Parts may not fit together at all
Components from different brands can’t be interchanged
Imported equipment becomes impossible to service
Factories can’t collaborate or share parts
In the early days of industrialization, each country defined its own system based on domestic needs, which led to a jungle of standards.
Today, however, the global market is essentially dominated by four major systems:
ISO, DIN, JIS, and ASME.
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2. Why These Four: ISO, JIS, DIN, and ASME?
There are many standards in the world, but these four became global mainstream for three main reasons.
(1) They cover the world’s major industrial ecosystems
ISO → International equipment, cross-border manufacturing, European factories
DIN → German and European machine tool systems
JIS → Japanese and Asian precision equipment (3C, semiconductor, automation)
ASME → U.S. mechanical engineering, construction, piping and pressure systems
In practice, over 90% of factories and machines fall under one of these four standards.
(2) Complete, well-documented, and widely supported by the supply chain
All four standard systems offer:
Full specifications for screws, nuts, washers, retaining rings, etc.
Open and well-documented standards that are easy to look up
Strong support from global suppliers like MISUMI, McMaster-Carr, Bossard
A mature supply chain where compatible parts are easy to source worldwide
In other words, these four systems have become a kind of “common language” of global manufacturing.
(3) Easier to cross-reference, convert, and verify
ISO, DIN, and JIS share many cross-reference equivalents (e.g. DIN 912 ≈ ISO 4762)
ASME works alongside ANSI and IFI with clear division of responsibilities
Compared to more regional standards (UNI, NF, KS, GB, etc.):
These four offer the best documentation, easiest cross-country comparison, and lowest risk of error in maintenance and replacement.
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3. Positioning and Background of the Four Major Standards
1. ISO (International) – The Most Widely Used Global Standard
The mission of ISO is simple:
Let the world manufacture and communicate using a unified set of standards.
Key characteristics:
Jointly developed by multiple countries
Emphasizes consistency, safety, and interoperability
Commonly seen in European equipment, automated production lines, and global systems
Many countries are progressively aligning their local standards to ISO
2. DIN (Germany) – A Symbol of Precision and Consistency
DIN has long earned the trust of Taiwanese factories and exporters, because:
Germany is a global leader in machine tools and precision manufacturing
DIN specifications are clear, highly precise, and inspection-oriented
Taiwan imported large volumes of German equipment in the past, so DIN became the de facto standard
In many factories, when people say “standard parts”, they often implicitly mean DIN parts.
3. JIS (Japan) – The Main Language of Precision Industries in Asia
JIS became widespread in Asia because:
Japan has a strong base in electronics, optics, 3C, and semiconductor industries
Taiwan and Korea have long relied on Japanese equipment
Taiwanese CNS and Korean KS are largely aligned with JIS/ISO
Characteristics:
Very strict dimensional and tolerance requirements
Well-suited for precision machining
Commonly found in automation modules, jigs, fixtures, and electronic equipment
If your equipment is from a Japanese brand, chances are JIS is the default standard.
4. ASME (United States) – The Backbone of Engineering and Pressure Systems
ASME’s role is broader than just screw specifications. It also governs:
Mechanical design, piping, boilers, and pressure vessels with a strong focus on safety.
Key points:
Uses both inch (imperial) and metric systems
Focuses on engineering analysis and safety factors
Widely applied in American machinery, construction, HVAC, piping, and hydraulic systems
In short:
Whenever you’re dealing with high-risk or engineering-grade systems, you’re very likely in ASME territory.
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4. The Relationship Between ASME and ANSI – A Common Source of Confusion
Many engineers mix up ASME and ANSI, so let’s clarify:
ANSI – Approves and oversees standards (“the ministry of education”)
ASME – Drafts and maintains technical engineering standards (“the textbook author”)
In practice:
Thread series (UNC, UNF) → Usually defined under ANSI / IFI
Equipment geometry, piping, pressure vessels → Governed by ASME
They are not in conflict; they work together with different roles.
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5. Comparison of the Four Major Standards
Standard | Measurement System | Core Characteristics | Typical Applications |
ISO | Metric | International, widely adopted | Automation, cross-border equipment |
DIN | Metric | High precision, strong German legacy | Machine tools, automation modules |
JIS | Metric | High precision, Asian mainstream | 3C, semiconductors, Japanese-brand equipment |
ASME | Imperial + Metric | Engineering / pressure systems focus | U.S. machinery, construction, piping systems |
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6. Which Standards Are Used on Which Equipment?
Each country developed its own industrial ecosystem, so the equipment coming from that country will naturally follow its local standards.
Once you know where the machine comes from, you can quickly guess whether it uses ISO, DIN, JIS, or ASME.
Equipment vs. Standards – Quick Reference
Equipment / Industry Type | Common Standards | Explanation |
European equipment, automated production lines | ISO, DIN | European industry is built around ISO/DIN |
German machine tools, automation modules | DIN | Taiwan historically imported many German systems |
Japanese equipment, 3C, electronics, semiconductor lines | JIS | Japanese brands dominate; high precision requirements |
U.S. machinery, construction, pressure vessels / piping | ASME | Strong emphasis on safety factors and structural integrity |
Taiwanese local machinery and custom equipment | Mix of DIN, JIS, and ISO | Equipment sources are diverse |
Imported American factories / OEM systems | ANSI, ASME | Mostly inch-based threads and U.S.-spec components |
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7. Tips to Avoid Mixing Standards
Always confirm the origin of the equipment
Distinguish metric vs. imperial from the start
Do not substitute one standard’s screws with another
Mixing standards can cause stripped threads, galling, or even fractures
If you’re not sure:→ Take clear photos, measure the key dimensions, and ask your supplier to verify
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8. Why Work with Sheng Fong Precision?
Sheng Fong Precision specializes in a mixed metric/imperial supply chain, helping you quickly:
Identify which standard your equipment uses
Cross-reference dimensions, head styles, thread pitches, and tolerances
Find compatible equivalents across ISO / JIS / DIN / ASME
Source alternatives for MISUMI, McMaster-Carr, and other global brands
Reduce downtime and prevent damage caused by using the wrong standard
📩 LINE: @s9000If you’re unsure which standard or replacement spec you should use, send us your requirements – we’ll help you find the correct standard and a reliable alternative.
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