Roll former speeds are typically given in feet per minute (fpm), which is fine when you’re calculating throughput, but when troubleshooting problems or designing elements of punching and cutting systems, you must typically convert line speed to inches per second (ips). Most events on a roll former occur in seconds, or fractions of seconds.
When converting from fpm to ips, you simply divide by 5. To convert from ips to fpm, multiply by 5. 5 is a constant for this formula, because there are 12 inches per foot, and 60 seconds per minute. 60 is evenly divisible by 12, therefore:
1 foot/12 inches ÷ 1 minute/60 seconds
1 foot/12 inches · 60 seconds/1 minute
1 foot/1 inch · 5 seconds/1 minute = 5 seconds(feet)/1 minute(inch)
Since you will always use this constant to convert feet, minutes, seconds and inches, you may drop the nomenclature and just use “5”.
80 fpm ÷ 5 = 16 ips
60 ips · 5 = 300 fpm