Hey there! I'm a supplier of forming taps, and while these tools are pretty awesome in many ways, they're not without their drawbacks. In this blog, I'm gonna break down some of the disadvantages of using a forming tap.
1. High Initial Cost
One of the most obvious downsides of forming taps is the high initial cost. Unlike cutting taps, which are relatively inexpensive to manufacture, forming taps require more complex machining processes and high - quality materials. The design of a forming tap needs to be extremely precise to ensure proper thread formation. You see, these taps work by displacing the material to create threads rather than cutting it away. This means that the tap has to be made with very tight tolerances, and that drives up the price.
For small - scale operations or hobbyists on a budget, this can be a real deal - breaker. If you're just starting out and don't have a lot of capital to invest in tools, spending a large amount on a forming tap might not be feasible. Even for larger businesses, the cost can add up quickly, especially if you need to stock different sizes and types of forming taps.
2. Limited Material Compatibility
Forming taps are not suitable for all materials. They work best with ductile materials such as aluminum, brass, and some types of steel. These materials can be easily displaced during the thread - forming process without cracking or breaking. However, when it comes to brittle materials like cast iron or hardened steel, forming taps are often a no - go.
Brittle materials tend to crack under the pressure exerted by the forming tap. Since the tap is pushing the material aside to form the threads, the stress can cause the material to fracture, resulting in a poor - quality thread or even a damaged workpiece. So, if you're working with a wide range of materials in your shop, you'll need to have both forming taps and cutting taps on hand, which adds to the overall cost and complexity of your tool inventory.
3. Require Higher Torque
Another disadvantage is that forming taps require higher torque to operate compared to cutting taps. Because they are displacing material rather than cutting it, more force is needed to push the tap through the workpiece. This means that you need a more powerful tapping machine or a stronger operator if you're doing manual tapping.
Higher torque requirements also increase the risk of tap breakage. If the machine isn't powerful enough or if the operator applies too much force suddenly, the tap can snap inside the hole. And once a tap breaks, it can be a real pain to remove, especially in a blind hole. You might end up having to scrap the workpiece, which is a waste of time and money.
4. Limited Thread Depth
Forming taps are generally limited in the depth of the threads they can form. As the tap goes deeper into the hole, the pressure required to displace the material increases significantly. At a certain point, the tap may not be able to generate enough force to continue forming the threads, or the tap itself may become overloaded and break.
This limitation can be a problem if you need to create deep threads in your workpieces. For example, in some industrial applications where you need long - lasting, high - strength threads, the limited thread depth of forming taps may not meet your requirements. In such cases, you'll have to resort to cutting taps, which can form threads to greater depths.
5. Sensitivity to Hole Diameter
Forming taps are very sensitive to the initial hole diameter. The hole needs to be drilled to a very precise size before tapping. If the hole is too small, the tap will encounter excessive resistance, which can lead to tap breakage or a poor - quality thread. On the other hand, if the hole is too large, the threads formed may not have the proper fit or strength.
This means that you need to be extremely accurate when drilling the holes for forming taps. You may need to use precision drilling equipment and take extra time to measure and verify the hole diameter. This adds to the overall time and cost of the machining process.
6. Difficult to Re - Sharpen
Unlike cutting taps, which can be relatively easily re - sharpened when they become dull, forming taps are much more difficult to re - sharpen. The shape of a forming tap is designed to displace material in a specific way, and any alteration to its profile can affect its performance.
Most of the time, once a forming tap starts to wear out, it's often more cost - effective to replace it rather than trying to re - sharpen it. This is because the re - sharpening process requires specialized equipment and skills, and there's no guarantee that the tap will perform as well as a new one after re - sharpening.
7. Not Ideal for Small - Diameter Holes
Forming taps are not the best choice for small - diameter holes. In small holes, the space for material displacement is very limited. The tap may not be able to form proper threads due to the lack of room for the material to flow.
Also, the high torque requirements become even more of an issue in small - diameter holes. The tap can easily break because the small cross - sectional area of the tap makes it more vulnerable to the high forces. So, if you're working on projects that involve a lot of small - diameter holes, cutting taps are usually a better option.
Conclusion
Despite these disadvantages, forming taps still have their place in many industries. They offer advantages such as stronger threads, better surface finish, and no chip disposal issues. But it's important to be aware of their limitations so that you can make an informed decision when choosing the right tapping method for your project.
If you're interested in learning more about Thread Forming Tap or if you're thinking about making a purchase, don't hesitate to reach out for a chat. We can discuss your specific needs and see if forming taps are the right fit for your operations.
References
- "Machining Handbook", Industrial Press Inc.
- "Metal Cutting Principles", by Joseph A. Schey
