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The variety of thread types is vast, and you've probably noticed this when you needed something more than just a regular screw. Each type of thread was developed for a specific purpose, and while they all serve the same basic function, their unique designs allow them to excel in different applications. However, one type stands out from the rest—**the saw thread**. It might not look like a traditional thread at first glance, but its design makes it highly specialized and useful in certain industries.
So, what makes the **saw thread** so special? Let’s take a closer look at its unique features and how it works.
### What Makes the Saw Thread Unique?
The name “saw thread†comes from its profile, which resembles the teeth of a saw. But despite the name, it doesn’t actually cut or have any direct connection to saws. Instead, its design gives it a distinct advantage in handling **one-sided loads**. Unlike most threads that are symmetrical, the saw thread has an **asymmetrical profile**, with two different angles on each flank.
### Asymmetrical Profile
Most threads—whether triangular, trapezoidal, or round—are symmetrical. The saw thread breaks this rule. Its two flanks have **different angles**, meaning the load-bearing side is much steeper than the non-load-bearing side. This asymmetry allows the thread to handle force in only one direction, making it ideal for applications where movement or pressure is unidirectional.
### Load-Bearing vs. Non-Load-Bearing Flanks
One of the key features of the saw thread is the distinction between the **load-bearing** and **non-load-bearing** flanks. The load-bearing flank is almost perpendicular to the axis, allowing it to generate significant axial force. The non-load-bearing flank, on the other hand, is more sloped, helping to guide the thread smoothly during operation.
For example, in metric saw threads, the load-bearing flank has a 3° angle, while the non-load-bearing flank has a 30° angle. Together, they form a total flank angle of 33°, often written as **30°/3°** for clarity.
### Designed for One-Sided Loads
Because of its asymmetrical design, the saw thread is best suited for **one-directional loading**. This makes it perfect for applications like **lifting spindles, screw presses, and clamping devices**. In these cases, the thread can efficiently transfer force in one direction without the need for reverse motion.
It's also used in **sealing connections**, especially in the oil and gas industry, where the ability to maintain a tight seal under axial pressure is crucial.
### Common Types of Saw Threads
There are several types of saw threads, each designed for specific applications:
#### Metric Saw Thread (German Saw Thread)
Known internationally as the **"German saw thread"**, this is the most commonly used variant. It has a total flank angle of 33°, with 3° on the load-bearing side and 30° on the non-load-bearing side. It's standardized under **DIN 513-1 to DIN 513-3** and available in sizes ranging from 10 mm to 640 mm. It's marked with the letter **S**.
#### 45° Flank Angle Saw Thread
Another popular variant has a **45° flank angle**, with the load-bearing flank perpendicular to the axis. There are also variations such as the **American ANSI saw thread**, which adds a 7° angle to the load-bearing flank.
#### Saw Thread for Plastic Containers
A specialized version is used in the **packaging industry** for plastic containers. Standardized under **DIN 6063-1**, it has a 10° angle on the load-bearing flank and 40° on the non-load-bearing side. It's marked with **KS**. There’s also a separate standard for trapezoidal threads in this application (**DIN 6063-2**), which should not be confused with the saw thread version.
### Tools for Working with Saw Threads
If you're working with saw threads, you’ll need the right tools. Special taps are required to create these unique profiles. You can find high-quality **taps and threading tools** in our **BAER online store**. We also offer a range of accessories to make your work easier. If you have any questions, our customer service team is always here to help.