Gear Accuracy Grades: DIN 3 to AGMA 15 Tables
Compare DIN, ISO, AGMA and GB gear precision systems with grade tables, speed-cost relationships and process guidance for transmission design.
1. Four Precision Standard Systems Overview#
Gear precision is the core indicator of transmission quality, directly affecting meshing smoothness, noise levels, load capacity, and service life. The four most widely used global standard systems are:
| Standard | Full Name | Region | Latest Version | Core Standard |
|---|---|---|---|---|
| DIN | German Industrial Standard | Germany/Europe | DIN 3961~3967 | DIN 3962 (Cyl. gear tolerances) |
| ISO | International Organization for Standardization | Global | ISO 1328:2013 | ISO 1328-1 |
| AGMA | American Gear Manufacturers Association | North America | AGMA 2015:2009 | AGMA 2000-A88 |
| GB | Chinese National Standard | China | GB/T 10095:2008 | GB/T 10095.1 |
Key Relationships: GB/T 10095 adopts ISO 1328 with modifications; DIN 3962 and ISO 1328 are highly consistent. DIN/ISO/GB are interchangeable in parameter definitions. Only AGMA uses a different grading logic.
2. Precision Grade Comparison Table#
2.1 Cylindrical Gear Precision Grade Cross-Reference#
| DIN Grade | ISO 1328 | GB/T 10095 | AGMA 2000 | Typical Process | Typical Application |
|---|---|---|---|---|---|
| DIN 3 | ISO 3 | GB 3 | AGMA 15 | Precision grinding | Aerospace, high-speed, precision indexing |
| DIN 4 | ISO 4 | GB 4 | AGMA 14 | Precision grinding | Auto transmission, precision machine tools |
| DIN 5 | ISO 5 | GB 5 | AGMA 13 | Grinding/fine hobbing | Automotive, general gearboxes |
| DIN 6 | ISO 6 | GB 6 | AGMA 11~12 | Hobbing + shaving | General industrial gearboxes |
| DIN 7 | ISO 7 | GB 7 | AGMA 10 | Hobbing | Agricultural, crane machinery |
| DIN 8 | ISO 8 | GB 8 | AGMA 8~9 | Hobbing | Low-speed, non-critical drives |
| DIN 9~12 | ISO 9~12 | GB 9~12 | AGMA 4~7 | Rough cutting/casting | Manual, low precision |
Geyontech Batch Capability: Batch production GB 4~5 (≈ DIN 4~5), precision grinding up to DIN 3 (≈ AGMA 15).
2.2 Precision Grade vs. Speed#
| Grade | Max Speed | Noise Level | Cost Multiplier (hobbing=1.0) |
|---|---|---|---|
| DIN 3 | > 35 m/s | Very low | ×5.0~8.0 |
| DIN 4 | 25~35 m/s | Low | ×3.0~5.0 |
| DIN 5 | 15~25 m/s | Medium-low | ×2.0~3.0 |
| DIN 6 | 10~20 m/s | Medium | ×1.5~2.0 |
| DIN 7 | 5~15 m/s | Medium-high | ×1.2~1.5 |
| DIN 8 | < 10 m/s | High | ×1.0 (baseline) |
| DIN 9 | < 5 m/s | Very high | ×0.8~1.0 |
3. Key Precision Parameters Explained#
3.1 Pitch Accuracy (Running Smoothness)#
- Single Pitch Deviation (fpt/fp): Adjacent tooth pitch variation → meshing impact noise
- Total Cumulative Pitch Deviation (Fp): Max pitch error across circumference → angular velocity fluctuation — the most critical parameter
- Engineering rule: Fp ≤ 0.5×module (μm) for general machinery; precision drives require Fp ≤ 25 μm
3.2 Tooth Profile Accuracy (Load Capacity)#
- Total Profile Deviation (Fα): Actual profile vs. theoretical involute → contact stress distribution
- Profile Form Deviation (ffα): Curvature deviation → micro-noise excitation
3.3 Helix Accuracy (Axial Meshing)#
- Total Helix Deviation (Fβ): Actual tooth trace vs. theoretical → tooth load distribution — main cause of misalignment
3.4 Radial Runout (Fr)#
- Eccentricity of gear ring relative to bore → periodic noise and vibration
4. Precision Grade vs. Process Chain#
| Target Grade | Recommended Process Route | Key Equipment | Geyontech |
|---|---|---|---|
| DIN 3~4 | Hobbing → Carburizing → Precision grinding | Worm/form grinding machine | DIN 3 |
| DIN 5~6 | Hobbing → Carburizing → Grinding | CNC grinder | GB 4~5 batch |
| DIN 6~7 | Hobbing → Shaving or post-HT grinding | Shaver/grinder | Stable mass production |
| DIN 7~8 | Precision hobbing | High-precision hobbing machine | Up to 5 sec/tooth |
| DIN 8~9 | Standard hobbing | Standard hobbing machine |
5. Export Market Precision Standards Guide#
5.1 Europe (DIN/ISO)#
- Recommended: DIN 5~7 (general), DIN 3~4 (precision)
- Documents: Full inspection report (Fp/Fα/Fβ/Fr), material cert, heat treatment report
- Key concern: Surface roughness (Ra ≤ 0.8 μm), tooth burn inspection
5.2 North America (AGMA)#
- Recommended: AGMA 11~13 (general), AGMA 14~15 (precision)
- Documents: Contact pattern check, noise test
- Note: Imperial DP (DP = 25.4/m) — watch DP/metric conversion
5.3 Southeast Asia / Middle East#
- Reference: DIN/ISO, some follow JIS
- Recommended: DIN 6~8, cost-performance priority
- Note: Shipping protection (anti-rust + soft tooth separators)
5.4 Precision Selection Decision Tree#
Speed / Load / Noise requirements
├─ High speed >25m/s + Low noise → DIN 3~4 / AGMA 14~15 → Grinding
├─ Medium-high 15~25m/s → DIN 5~6 / AGMA 11~13 → Grinding/precision hobbing
├─ Medium 5~15m/s → DIN 6~7 / AGMA 10~11 → Hobbing+shaving
└─ Low <5m/s → DIN 8~9 / AGMA 7~9 → Standard hobbing
6. Common Misconceptions#
| Myth | Fact |
|---|---|
| Higher precision is always better | Each grade adds 50~100% cost. Choose adequate, not highest |
| DIN/ISO/GB are directly interchangeable | Parameters match, but DIN 3 tolerances are slightly stricter than ISO 3 |
| AGMA higher number = higher precision | Correct (AGMA 15 highest), but AGMA 15 ≠ DIN 7 — it equals DIN 3 |
| Hobbing can replace grinding for DIN 4 | Hobbing limit ≈ DIN 4, but post-HT deformation requires grinding |
7. Geyontech’s Precision Capability#
| Item | Capability |
|---|---|
| Batch precision | GB 4~5 (consistent) |
| Max grinding | DIN 3 |
| Full inspection | Gear measuring center + CMM + meshing tester |
| Fp | ≤ 25 μm (DIN 5) |
| Fα | ≤ 10 μm (DIN 4~5) |
| Fβ | ≤ 10 μm (DIN 4~5) |
| Fr | ≤ 15 μm |
| Ra | ≤ 0.8 μm (grinding), ≤ 0.4 μm (superfinish) |
| Report formats | DIN / ISO / AGMA / GB |
| Certifications | CE / CSA / BV / SGS / UL |
13 years of gear industry experience. Geyontech’s engineering team provides precision grade recommendations at the quotation stage — matching the most cost-effective grade combination to your export destination, speed, load, and noise requirements.
8. Summary#
| Scenario | Standard | Grade | Process | Cost |
|---|---|---|---|---|
| Export Europe, precision machines | DIN | DIN 3~5 | Hobbing+grinding | ~ |
| Export North America, auto drives | AGMA | AGMA 13~15 | Hobbing+grinding | |
| General industry, SE Asia | ISO/DIN | DIN 6~7 | Hobbing+shaving | ~ |
| Low-speed, non-critical | GB | GB 8~9 | Standard hobbing |
Contact us with your application parameters (power, speed, ratio, export destination) — Geyontech’s engineering team returns a precision proposal and quotation once the drawing review is complete.
Dongguan Geyon Transmission Technology Co., Ltd. — Precision Gear Manufacturing & Transmission Components Export
- info@geyontech.com | geyontech.com*