The Importance of Belt Speed for Your Grinder
Belt Speed
Belt speed is an essential factor when selecting the correct type of grinder for your application. Belt grinding is a function of belt speed, horsepower, and the ability to apply force. If you take any one of the three factors away, you are no longer grinding, you are sanding. Burr King takes pride in our ability to manufacture top of the line belt grinders, capable of reaching the belt speed you need, to get the job done right.
Keep reading below to learn more about why proper belt grinder speed is critical and the Burr King grinder machines that are available to help you.
What is SFPM?
Surface Feet Per Minute (SFPM) is a critical parameter in grinding and polishing operations. It measures the speed at which the abrasive belt moves over the surface of the material being worked. Understanding and selecting the proper SFPM for your specific task is essential because it directly impacts cutting efficiency, surface finish, and abrasive belt life.
SFPM is important because it:
- Impacts Removal Rate: Higher SFPM increases the material removal rate, making it ideal for aggressive grinding tasks. Lower SFPM provides more control and is suitable for fine polishing or delicate work.
- Creates Heat Generation: Excessive SFPM can generate too much heat, leading to material warping, discoloration, or abrasive degradation. Proper SFPM minimizes heat build-up, reducing the risk of material damage.
- Extends Belt Lifespan: Operating at the correct SFPM extends the life of your abrasive belt. Over-speeding causes premature wear, while under-speeding reduces cutting efficiency.
- Provides Surface Finish: Consistent and appropriate SFPM ensures the desired surface finish, whether rough for adhesion or smooth for aesthetic appeal.
How Does SFPM Impact Grinding?
Simply put, a minimum belt speed is required to perform actual grinding work. Without belt speed, no real grinding work will actually be done and your project time will dramatically increase as your part remains continually unfinished.
The type of belt you choose and the belt speed you select will vary based on the material you are working with and your desired finish. Finer finishes normally need a slower belt speed because finer belts cause more friction, which converts to heat and will affect the finish negatively.
Example: A piece of carbon steel using a 320 grit belt running at 7,000 Surface Feet Per Minute will cause a tremendous amount of friction/heat. The 320 grit belt will not remove material efficiently. The result will be excess heat and damage to the composition of the steel. Running the abrasive belt at a slower SFPM will allow the operator to control the heat buildup in the steel. If the objective were to remove a large amount of material, choosing a more coarse belt and running it at 7,000 Surface Feet Per Minute would produce an efficient material removal rate and create less heat.
Proper belt speed on your grinder directly impacts your part’s finish and cut rate. A grinder’s belt SFPM speed will vary based on a variety of factors including desired finish, belt grit, and belt composition and material. The rate of cut depends on choosing the correct speed, the right abrasive material, and the optimum pressure for desired results.
To calculate your grinder’s SFPM capability, use our SFPM calculator to ensure you have the right grinder capabilities for your project.
Example: If your belt grinder has a 3450RPM motor running an 6” drive wheel, you would use 3450 for the RPM and 6” wheel diameter to create a SFPM of 5419. You can use our calculator even if you don’t own a Burr King belt grinder.
As mentioned above, different materials will require different grinding speeds due to the material’s density and composition. Use the chart below to determine what SFPM you need to operate your belt to properly grind your chosen material.
Off-Hand Grinding Abrasive Speed Recommendations |
||
| Alloy |
Belt Speed (SFPM) (Surface Feet Per Minute) |
Belt Grit |
| Cast Iron | 7,000 – 8,000 | 24 – 120 |
| Carbon Steel | 6,500 – 8,000 | 24 – 120 |
| Stainless Steel | 6,500 – 7,000 | 36 – 120 |
| Nickel Alloys | 6,000 | 36 – 120 |
| Titanium | 2,500 – 3,000 | 26 – 180 |
| Aluminum | 7,500 – 8,000 | 24 – 120 |
| Aluminum | 6,500 – 7,000 | Fine Grades |
| Brass | 7,000 – 8,000 | 36 – 180 |
| Rubber | 4,500 | 36 – 180 |
| Glass | 2,500 – 8,000 | 80 – 4000 |
| Stone | 7,000 | 36 – 180 |
Note: SFPM can be affected by many variables. This chart is a typical recommended speed and you may find that a different speed works well for your unique applications.
Burr King Grinders’ SFPM Capabilities
Burr King grinders are renowned for their versatility and range of SFPM settings. Our models can achieve variable SFPM by adjusting belt speed, providing flexibility for different grinding and polishing applications. Burr King belt grinders are indirect drive, so the RPM of the motor doesn’t dictate the final RPM of the shaft that the contact wheel is located on. If you want the most versatile machine, Burr King belt grinders with Variable Speed will get the job done. Nearly every machine we manufacture can be purchased with variable speed. As abrasive manufacturers engineer abrasives to run at a wider range of speeds efficiently, you can always rest assured that a Burr King with a variable speed will handle the job.
Example: The Burr King Model 760, using a VFD (variable frequency drive), will have a speed range of 410-4140 RPM at the spindle with a 1725 RPM motor.
Optimize Your Grinding & Polishing Processes
By understanding SFPM and selecting the appropriate abrasive belt, you can optimize your grinding and polishing processes for efficiency and quality. Burr King belt grinders are ideally designed for versatility and durability to ensure you can complete any grinding or finishing project correctly.
Want more information on Burr King equipment? Contact us today!