1. Product Description

This document details specifications for twist drills designed specifically for steel drilling, featuring internal coolant channels. The drills are manufactured from micrograin carbide (HM) grades K20-K40 and conform to DIN 6527 standards. They have a 30° helix angle and a 140° point angle, with flute length variants expressed as multiples of the drill diameter (3XD, 5XD, 8XD, 12XD), indicating different drilling depth capabilities.

2. Dimensional Data and Tolerances

Drills are categorized by codes starting with '178' and include parameters such as nominal diameter (Dc), diameter tolerance class (m7 or h7), flute length (L2), overall length (L1), and shank diameter (D2). Diameters range from 1.00 mm to 20.00 mm, with flute and overall lengths increasing proportionally. Diameter tolerances (m7 or h7) ensure precision suitable for various machining requirements.

3. Drill Series and Length Variants

• 178 3XD Series: Short flute lengths for standard drilling depths.
• 178 5XD Series: Medium flute lengths for moderately deep holes.
• 178 8XD Series: Longer flute lengths for deep hole drilling.
• 178 12XD Series: Longest flute lengths for very deep hole applications.

4. Material and Coating

The drills are made from micrograin carbide grades K20-K40, providing high hardness and wear resistance optimized for steel. Internal coolant channels enhance cooling efficiency and chip evacuation, improving tool life and machining performance.

5. Key Parameters and Dimensions

Typical examples include a 3.00 mm diameter drill in the 3XD series with L2=20 mm and L1=62 mm, and a 20.00 mm drill in the 12XD series with L2=190 mm and L1=243 mm. Shank diameters correspond closely to drill diameters to ensure proper tool holding.

6. Standards and Norms

The drills comply with DIN 6527, which standardizes twist drills with internal coolant. The geometry—30° helix angle and 140° point angle—is optimized for steel drilling applications, ensuring efficient cutting and chip removal.

7. Best Practices and Recommendations

• Select the appropriate flute length series (3XD, 5XD, 8XD, 12XD) based on required drilling depth.
• Choose diameter tolerance class (m7 or h7) according to precision needs.
• Utilize internal coolant channels to enhance tool life and machining efficiency.
• Ensure compatibility with machine tool holders matching the shank diameter.
• Adhere to DIN 6527 standards for quality assurance and tool interchangeability.

8. Summary Tables and Data

The document includes extensive tables listing drill codes, diameters, tolerances, flute lengths, overall lengths, and shank diameters. These serve as a comprehensive reference for selecting drills tailored to specific machining requirements, covering diameter ranges from 1.0 mm to 20.0 mm and length-to-diameter ratios from 3XD up to 12XD.

9. Conclusion

This technical specification document provides a thorough reference for micrograin carbide twist drills with internal coolant channels designed for steel drilling. It offers detailed dimensional data, tolerance classes, material grades, and standardized geometry to guide users in selecting the optimal drill size and length for their machining applications, ensuring precision, durability, and performance.