A flange is a small yet critical tool in the synchronous pulley system. For applications in which consistency is absolutely critical, flanges play an invaluable role in operational stability and misalignment prevention. Below, we discuss what a pulley flange does in a synchronous belt drive, how flanges are produced, and the various methods utilized by manufacturers to attach flanges to pulley systems.
What Does a Pulley Flange Do?
A flange is a critical tool in many pulley systems. Pulley flanges are the small rings attached to the pulley, sitting on either side of the teeth. The pulley belt rides between each flange, keeping the belt securely in place. The flange is important because of the tendency of belts to track to one side or another – known as angular misalignment. Misalignment can occur from a variety of reasons, including varying loads or tensile cord patterns.
Regardless of the precise reason, belt misalignment can result in belt edge wear or system failure. Thus, utilizing flanges in the proper way, on the proper belt drive structures, is critical to a smoothly running pulley system.
Which Pulleys Need Flanges?
In general, all synchronous belt drive systems should utilize at least one flange. For belt drive configurations with multiple pulleys, proper tracking is especially critical, and multiple flanges may be required. Guidelines for specific pulley systems are listed below.
- Two Timing Belt Pulley Drives: these simple pulley systems require at least one pulley flanged on both sides. Alternatively, each pulley should be flanged on opposite sides to ensure secure operation.
- Multi Timing Belt Pulley Drives: for belt pulley drives with multiple synchronous pulleys, every pulley should have a pulley on alternative sides. Or, at least every other pulley should be flanged on both sides.
- Vertical Shaft Drives: these drives require that one cog pulley should be flanged on both sides, and any remaining pulleys should have at least one flange on the bottom side.
- Long Span Drives: long span drives often demand the most security pulley systems – both timing belt pulleys should be flanged.
The Flange Production Process
Timing pulley flanges are most commonly made from metals or plastics. Ordinary flange metals include aluminum, carbon steel, stainless steel. Nylon, and polycarbonate are the most popular flange plastics.
In most instances, pulleys can be purchased with flanges. If a pulley system does not yet have a flange, the piece is produced specifically to fit timing pulleys, down to pitch and size. Additionally, most pulley flanges can be ordered in English and metric units.
Once the precise size and configuration of the timing pulley system is determined, the flange can be made accordingly. A produced flange must then be connected to the pulley system before use.
How Are Flanges Attached to the Pulley System?
Attachment methods vary between manufacturers, and certain flanging processes are better than others. Thus, it is critical to learn about a manufacturer’s specific flanging process before purchasing product.
Three flanging process methods are most common:
1. Staking vs. Roll Staking
Staking is one of the most common flange attachment processes. Within this method, 8 to 10 points are deformed around the edge of the pulley. The deformed material is used to retain the flange in place. The downside of the typical staking process is instability. As only the 8 to 10 deformed spots hold the flange in place, thrusting or wear can pop it loose over time.
Roll staking is commonly used to attach flanges to small timing pulleys. As mentioned, many conventional staking methods crimp 8 to 10 points around the edge of the flange – roll staking crimps around the entire flange. Because roll staking holds the flange to the pulley around the entirety of the flange edge, roll staking is a safe, secure flanging process, especially for small timing pulleys.
2. Heat Shrinking
When a heavy, large flange is being attached to a timing pulley, heat shrinking is often the preferred method. In the heat shrinking process, flanges are heated to at least 450 degrees Fahrenheit and placed on the pulley. The pulley’s flange step – where the flange is attached – will be slightly larger than the diameter of the flange in its cold state. When the flange cools, it shrinks onto the pulley flange step, permanently affixed.
Heat shrinking is highly effective and completely reliable.
3. Bolt-On Flanges
Bolt-on flanges are unique for two primary reasons: they are the heaviest and most durable flanges available, and they can be removed for timing belt maintenance. In the bolt-on process, the flange is bolted to the side of the pulley by durable flat head screws. These screws can be removed for maintenance as needed, unlike most other flanging methods.
Illinois Pulley & Gear
At Illinois Pulley & Gear, we specialize in high-precision timing belt pulleys and pulley stock. We also guarantee a durable, trustworthy flanging process. While in use, pulley motion cannot stop – thus, properly secured flanges are necessary to consistent synchronous pulley operation.
To learn more about our components or flanging process, please reach out at 847.407.9595 or via our online contact form! We look forward to speaking with you, listening to your needs, and solving issues with friendly customer service and quick turnaround time.