Surface feet per minute (SFPM or SFM) is the combination of a physical quantity (surface speed) and an imperial and American customary unit (feet per minute or FPM). It is defined as the number of linear feet that a location on a rotating component travels in one minute.

Cobalt is the most widely added binder or ‘cement’ in cemented tungsten carbides due to its function to wet tungsten carbide grains on the process of liquid phase sintering. So, cobalt is considered to be superior to other binder when it comes to eliminating residual porosity and gaining high strength and toughness properties in sintered products. Nevertheless, the failure of cemented carbides in corrosive conditions is mostly due to the chemical reaction of cobalt with corrosive agents. The corrosion process includes the dissolution of cobalt binder on the contact surface leaving a loosely knit skeleton of tungsten carbide grains with rarely structural integrity. This process is often defined as cobalt “leaching” and is typically accompanied by a spalling of unsupported carbide grains on the exposed surfaces.

Corrosion resistance is considered one of the most important properties for tungsten carbides, it shows significant importance when it comes to applications such as seal rings, fluid control components, choke valves, nozzles, and bearings. Although tungsten carbide is of better corrosion resistance compared with other steel alloys in general, there are still things we need to pay attention to when choosing the correct corrosion-resistant strength tungsten carbide.

Inches per minute (IPM) is a speed measurement of how many inches traveled in a minute, without regard to direction. In machining, it is primarily used as a feed rate (imperial units).

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A CNC mill calculates speeds and feeds or SFM based on the information the user enters. The type of CNC mill, the type of machine controller, and the age of the machine will affect the amount of information that can be input directly into the machine. Historically G-code was created externally from a CNC machine and then loaded onto the machine. Externally created G-code was authored either with a dedicated CAM software or with a plug-in embedded in the 3D parametric modeling software. The user would input the same CNC machine they want to create the part on (with the specific work holding fixture), the type of tooling (manufacture, part number etc.), and the specific material being machined. The software generates the speeds and feeds based on the part's geometry and all the inputted information. This creates the optimal speeds and feeds or SFM tailored to the exact part and CNC machine.

SFM to RPM

We has been devoted to producing precision carbide components for 20 years. Our products scope covers precision carbide punch, bushes, tungsten rod, ejector pin, stamping mold, Motor connector stamping mold etc.

Although tungsten carbide with Cobalt binder grains have nice resistance to corrosion of gasoline, acetone, ethanol, other organic solvents, ammonia, bases, weak acids, and tap water. However, the binder can be rapid deteriorated after exposure to hydrochloric,hydrofluoric, and other strong acid. Corrosion strength are also affected by temperature, density and electric conductivity of the corrosive agents. Alloying cobalt with chromium, molybdenum, or nickel can improve the corrosion resistance of the binder, but the total substitution of nickel for cobalt has proven to be the most effective means of increasing the lifespan of tungsten carbides in strong corrosive environments.

Tapping Speed

These calculations are based upon theoretical values and are only intended for planning purposes. Actual results will vary. No responsibility from Kennametal is assumed.

Note: The circumference unit is in inches and is dependent on if it’s a milling or turning operation. For milling operations, the circumference is of the cutter (tool in the spindle). For turning operations, the circumference is of the workpiece (the material in the chuck).

Dongguan JLS Precision Mold Parts Co.,Ltd imports tungsten carbide with fair and/or excellent corrosion resistance strengths depending on the different applications. For normal precision carbide punch for stamping die, the cemented carbide with “fair corrosion resistance strengths ” is working fine. The selection of tungsten carbides totally depends on which circumstances the carbide button dies used in.