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ASME B94.27.1M-1983 — Die Buttons: Basic Taper Relief, Press Fit (Metric)
⭕ ANSI/ASME B94.27.1M-1983 is the metric (SI) edition of the American National Standard for die buttons. Its full title, “Die Buttons — Basic Taper Relief, Press Fit (Metric),” confirms that it mirrors the inch edition B94.27-1970 in construction, types, and cutting-edge geometry, differing only in that every dimension is given in millimeters. Sponsored and published by the American Society of Mechanical Engineers and issued on November 15, 1984, it serves stamping dies designed and manufactured in metric units — an essential building block of metric stamping tooling standardization in international engineering environments.
💡 B94.27.1M and B94.27 are two unit-system editions of the same standard: the metric edition serves die designs drawn in millimeters, with identical edge construction and press-fit principle. Choose the edition that matches your unit system.
1. Standard Theme and Publication Data 📌
The theme is the standardization of metric press-fit die buttons. The cover carries the American National Standard designation, sponsored and published by ASME, with a date of issuance of November 15, 1984. The body covers:
- Metric die button types and dimension tables (in millimeters).
- Geometry of the straight bore land, taper-relief section, and OD press-fit section.
- Overall length, head structure, and press-in lead-in chamfers.
⚠️ The metric edition is not a simple conversion of the inch edition. B94.27.1M dimensions are independently selected preferred metric values, not rounded inch numbers. Never mix buttons from the two editions in one die.
2. Metric Dimension System vs. the Inch Edition 🔧
| Design Element | Metric Edition (B94.27.1M) | Inch Edition (B94.27) |
|---|---|---|
| Unit of measure | Millimeters (mm) | Inches (in) |
| Bore grades | Metric punch diameter series | Inch punch diameter series |
| Taper relief angle | Identical (angles are unit-free) | Identical |
| Press-fit allowance | Metric tolerance/interference system | Inch tolerance/interference system |
| Edge geometry | Straight land + taper relief | Straight land + taper relief |
💡 The taper-relief design intent is identical in both editions: a short straight land at the top of the bore preserves blanking accuracy, and a flared taper below discharges pierced slugs cleanly and self-aligns them, reducing slug hang-up and double cutting.
3. Function and Construction 📏
The metric die button performs the same function as the inch version — the female shearing element of a stamping die:
- Shear land: the straight land at the bore top pairs with the punch to form the shearing pair that determines part edge quality.
- Slug discharge: the taper-relief section guides slugs downward for clean ejection.
- Press-fit retention: the OD is pressed with interference into the die-shoe bore, resisting blanking reaction forces and holding position.
🚨 Replace a worn button wholesale with the metric grade; never patch the relief section. Metric and inch series buttons are not interchangeable — always verify the unit system and bore grade before ordering or fitting.
4. Materials and Heat Treatment 🛠️
Metric die buttons follow the same material practice as the inch edition:
- High-carbon, high-chromium cold-work die steel (D2-type): excellent wear resistance for medium-to-high volume blanking.
- Bearing steel (52100-type): cost-effective for general blanking duties.
- Powder-metal high-speed steel or carbide: for ultra-long life, high-speed blanking, and difficult materials.
💡 Metric button bores carry metric tolerances and are measured with metric gages (bore micrometers, plug gages), integrating seamlessly with ISO dimensioning — ideal for metric toolrooms that machine, inspect, and interchange parts directly.
5. Engineering Practice Essentials 📋
- 🔍 Selection workflow: derive the bore from the metric punch diameter plus clearance → choose the nearest standard metric bore grade → select overall length from shoe thickness → verify press-fit interference.
- 🔨 Pressing: press vertically with a press, using a pilot pin for alignment to protect the land; calculate press force from interference and material.
- 🔧 Clearance check: verify the actual punch-to-button clearance after mounting to ensure edge quality.
- 📏 Maintenance: keep land-wear measurement records and maintain at the standard replacement threshold to prevent burr growth from affecting product quality.
6. Frequently Asked Questions ❓
❓ Q: What is the difference between B94.27.1M-1983 and B94.27-1970?
A: Same subject — press-fit die buttons with basic taper relief. B94.27.1M uses millimeter dimensions and independently chosen metric preferred sizes; B94.27 uses inches. Edge construction and press-fit principle are the same.
A: Same subject — press-fit die buttons with basic taper relief. B94.27.1M uses millimeter dimensions and independently chosen metric preferred sizes; B94.27 uses inches. Edge construction and press-fit principle are the same.
❓ Q: How is the metric button bore determined?
A: Button bore = punch diameter + total (both sides) die clearance; clearance is typically 3%–8% of stock thickness depending on material. Pick the closest metric standard bore and finish the land to the target dimension.
A: Button bore = punch diameter + total (both sides) die clearance; clearance is typically 3%–8% of stock thickness depending on material. Pick the closest metric standard bore and finish the land to the target dimension.
❓ Q: Why can’t the metric and inch editions be mixed?
A: Because each edition uses its own independent series of preferred sizes — metric values are not conversions of inch values. Mixing them breaks clearance, interference, and punch matching, degrading accuracy and retention.
A: Because each edition uses its own independent series of preferred sizes — metric values are not conversions of inch values. Mixing them breaks clearance, interference, and punch matching, degrading accuracy and retention.
🔍 Q: What practical benefits does taper relief bring to the die?
A: It reduces friction between the slug and the bore wall, prevents slug packing and re-pull, stabilizes blanking force, extends land life, and improves edge quality and automatic slug discharge.
A: It reduces friction between the slug and the bore wall, prevents slug packing and re-pull, stabilizes blanking force, extends land life, and improves edge quality and automatic slug discharge.
