First introduced nearly 35 years ago, small surface planers (scarifiers) have seen their acceptance and use on municipal maintenance projects grow significantly. The flails on these surface planers are the heart and soul of material removal. They define how fast the material is removed and the final surface finish. Proper selection, operation, and maintenance will allow for faster material removal and maximize the return on investment.
All surface planers have the same platform configuration, but their power sources vary from gasoline and diesel engines to electric, and even pneumatic, motors. Some are propelled manually; others are self-propelled. Power is transferred through a belt reduction connected to a high-speed rotating drum—a standard design because the belt can minimize the amount of destructive resonance transferred back to the power source. Drums come in a variety of diameters and widths. Cutting width, commonly 8, 10, or 12 inches, is the standard for surface planers classification.
Surface planers use a rotating drum loaded with rows of flails that impact directly against a target surface. This flailing transfers a large amount of kinetic energy to strike against and subsequently remove material.
How much material is actually removed with flails depends on a number of factors, including drum/flail configuration, tensile strength of the material being removed, and the machine's travel speed.
Several flail configurations have been developed to meet increasing job applications. For easier selection and inventory reduction, many designs have been consolidated or eliminated over the years.
Today, four basic flail configurations are sold (see below). Each is available in various industry standard diameters and thicknesses, and named by its specific tooth configuration. Click on the name of each flail to see an image in a new window.
Star flails: are stamped from high manganese content alloy steel and are through hardened for additional service life. They produce a fine, broom-swept texture. Depending on the specific application, star flails will last one to three hours. Typical applications include:
Removal of coatings and encrusted materials
- Cleaning concrete and asphalt surfaces
- Light scarification before applying a new surface coating
- Steel deck de-scaling projects.
Beam flails, like star flails, are stamped from high manganese content alloy steel and are through hardened for added durability. They produce a medium-coarse to coarse texture finish. Normal service life is one to three hours, depending on the application. Typical applications include:
Removal of thicker coatings and encrusted materials
- Medium-duty concrete and asphalt removal
- Removal of traffic lines.
Tungsten carbide tipped flails feature extremely durable tungsten carbide inserts brazed in a perimeter around an alloy steel body. Popular configurations are five- or six-sided. Their higher quality construction delivers maximum performance and return on investment for most material removal projects. Tungsten carbide tipped flails produce a medium to coarse surface texture. The flails can last up to 250 hours. Typical applications include:
Heavy-duty concrete and asphalt removal
- Removal of trip-and-fall hazards on sidewalks
- Concrete and asphalt grooving projects.
Milling flails also incorporate rectangular tungsten carbide inserts brazed around the perimeter of an alloy steel body. The configuration is similar to that of standard machine tool cutters, making milling flails directional in nature. They must be operated in an upcut or climb cut mode.
Most manually propelled planers should be pulled toward the operator. If the planer is pushed forward, the flails will downcut, causing wear on the back side of the inserts and significantly decreasing the service life of the flails (Click here to read a sidebar on flail wear). With proper operation, milling flails can last up to 30 hours, depending on the specific application.Typical applications include:
Removal of traffic lines from concrete and asphalt surfaces
- Removal of membrane type materials from concrete surfaces.
By choosing the right flail for your application, you can optimize material removal, achieve the right finish, and maximize your return on investment.
— Dennis Von Ruden is president of General Equipment Co. in Owatonna, Minn.