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2023-04-10

Blind Hole: A hole that does not go through the entire workpiece. The bottom is closed.
Through Hole: A hole that is completely open on both ends, passing through the material.

Specifically designed for blind hole tapping
Upward chip evacuation prevents chip clogging at the hole bottom
Reduces the risk of tap breakage and improves tool life
Well-suited for ductile materials like stainless steel, carbon steel, and aluminum alloys

For through holes, straight flute taps are generally preferred since chips can fall out naturally
However, spiral flute taps can also be used in through holes when machining soft materials or when a high-quality surface finish is needed
Choose a lower spiral angle (e.g., 15° or 20°) for through hole applications

Hole Type	Material	Recommended Tap Type	Spiral Angle Suggestion
Blind Hole	Stainless steel, aluminum	Spiral Flute Tap	35° or higher
Through Hole	Cast iron, carbon steel	Straight Flute / Low-Angle Spiral	15°–20°

Always match the material type, hole depth, and chip removal direction when selecting the tap
Consider HSS, HSS-E, or carbide taps depending on production volume and hardness requirements
Use appropriate lubrication and cutting speed to extend tap life and maintain thread quality

Let me know if you'd like an illustrated version or tap selection chart for a catalog or website!