When it comes to CNC machining or custom part manufacturing, precision in hole features can make or break the assembly quality. Two terms often used in engineering drawings are tapped holes and threaded holes. While they sound similar, understanding the subtle differences can help you choose the right feature for your application and communicate effectively with your machining supplier.
Table of Contents
1. What Is a Tapped Hole?
A tapped hole is a hole that has been drilled and then threaded using a tap—a cutting tool specifically designed to form internal threads.
Process:
- Drill a hole to the required size (tap drill size).
- Use a tap to cut the internal threads.
Typical Applications: Fastening components where a screw or bolt will be inserted directly into the base material.
Advantages:
- Strong thread engagement.
- Simple process for many metals and plastics.
Limitations:
- Tapping is best for smaller quantities or lower hardness materials.
- In harder materials, taps may wear quickly or break.
2. What Is a Threaded Hole?
A threaded hole is a general term for any hole that contains internal threads, regardless of how those threads are made.
Manufacturing Methods:
- Tapping (Cutting threads with a tap).
- Thread milling (Using a CNC milling cutter to generate threads).
- Thread forming (Cold-forming threads without cutting material).
- Molded threads (Formed directly during injection molding).
- Thread inserts (Helicoil or solid inserts for added strength).
Advantages:
- Greater flexibility in manufacturing method selection.
- Can be optimized for strength, wear resistance, or repairability.
3. Key Differences Between Tapped Holes and Threaded Holes
| Feature | Tapped Hole | Threaded Hole |
| Definition | Specifically made by cutting threads with a tap | Any hole with internal threads, regardless of method |
| Process | Drilling + tapping | Tapping, milling, forming, molding, inserts, etc. |
| Scope | Subset of threaded holes | Broad category |
| Cost | Generally cost-effective for small/medium runs | Depends on method, can be higher for special requirements |
| Strength Options | Limited by base material | Can be enhanced with inserts or special processes |
4. Choosing the Right Hole Type for Your Part
When deciding between a tapped hole and other types of threaded holes, consider:
- Material: Softer metals and plastics work well with tapping; harder materials may require thread milling or forming.
- Production Volume: For high-volume production, thread forming or molding may offer better tool life and consistency.
- Thread Strength: If high pull-out strength is needed, consider threaded inserts.
- Tolerance Requirements: CNC thread milling can achieve tighter tolerances than manual tapping.
5. How We Can Help
At YP-MFG, we provide precision CNC machining services for both tapped and threaded holes, supporting:
- Over 100 materials including aluminum, stainless steel, brass, titanium, and engineering plastics.
- Multiple threading methods: tapping, thread milling, thread forming.
- Custom prototypes and large-scale production runs.
- Strict ISO 9001 quality control to ensure thread accuracy and fit.
Whether you need a simple M6 tapped hole in aluminum or a high-precision milled thread in titanium, our engineering team can help optimize the design and manufacturing process for your project.
Contact us today to discuss your part design and get a free quote for tapped or threaded hole machining.
