Tapped Hole vs Threaded Hole

In injection molding and precision manufacturing, understanding the difference between tapped hole vs threaded hole is crucial for optimal part design and functionality. We’ll explain these two common threaded fastening solutions and their best applications.

What is a Tapped Hole?

A tapped hole is created by cutting threads directly into the material after drilling. In injection molding, this can be achieved through:

• Post-molding tapping (using CNC or manual tapping tools)
• Molded-in threads (formed directly by threaded cores in the mold)

Tapped holes work best with engineering-grade plastics like POM, nylon, or reinforced polymers that can maintain thread integrity.

What is a Threaded Hole?

Threaded holes typically incorporate metal inserts to reinforce the threading. Common types include:

• Brass threaded inserts
• Helicoils
• Press-fit threaded bushings
• Ultrasonically welded inserts

These are essential for softer plastics (PP, ABS) or applications requiring frequent assembly/disassembly.

Forming Processes Comparison of Tapped Hole Vs Threaded Hole

Tapped Holes:

• Molded-in threads: Threads formed directly by mold cores (higher tooling cost)
• Post-molding tapping: Secondary operation after part ejection (lower mold cost)

Threaded Holes:

• Insert molding: Metal inserts placed in mold before injection (strongest bond)
• Post-mold insertion: Inserts added after molding (more flexible process)

Key Differences of Tapped Hole Vs Threaded Hole

• Excessive material temperature: Causes the part to adhere too strongly to the mold.
• Poor material flowability: Makes it difficult to eject the part from the mold.