Conversion
Inch and millimetre, cutting values, hardness, pressure, and other units.
In short: Conversion
The converters translate manufacturing units: inches and millimetres, cutting speed in m/min and SFM, temperatures, weights, times, angles, wire gauges, screw sizes and roughness values. Exactly defined conversions such as 1 inch = 25.4 mm are exact; conversions between roughness parameters remain approximations.
Frequently asked questions about Conversion
How do you convert inches to millimetres?
Since 1959 one inch has been internationally defined as exactly 25.4 mm. 3/8 inch is therefore 9.525 mm, and one thousandth of an inch equals 0.0254 mm.
How do you convert SFM to m/min?
1 SFM (surface feet per minute) equals 0.3048 m/min. 500 SFM is therefore 152.4 m/min; conversely, divide a value in m/min by 0.3048 to get SFM.
Can Ra be converted to Rz?
Not exactly. Ra is the arithmetic mean roughness and Rz the mean roughness depth; their ratio depends on the machining process and the profile. As a rough rule of thumb, Rz on turned and milled surfaces is about 4 to 7 times Ra. For acceptance, the parameter required on the drawing applies.
What do gauge numbers for sheet and wire mean?
Gauge is not a length unit but a number series whose thicknesses depend on the system and material. 16 gauge is about 1.52 mm for steel sheet according to the Manufacturers' Standard Gauge and about 1.29 mm according to the American Wire Gauge commonly used for aluminium. The system used must therefore always be stated.