Horsepower Calculations in paper converting


Thread Starter

John Anderson

Does anybody know of any good refrences on motor horspower sizing? I have an application with a certain size roll that weighs X amount and need some much tension, what size motor do I need to pull the paper. Applications like that. Primarily in paper converting applications. I am not very expierenced in sizing applications but would like to learn. If you could suggest some books, websites classes ect. Hope you can help.

I shall attempt to point you in the right direction with what I believe your question of Horse Power sizing is. Unfortunately I do not know much about the 'paper converting' so plese bear with me.

Let's asume that, what you are asking is, what size (Watts or HP) motor would I need to drive a roll of paper feeding into some aparatus
(printing ?). Then, you'll need to consider the geometry of the rolls of paper and the inevitable shaft and its' interface to the motor.
I would assume some sort of regulation is required to control the rate at which the paper is fed. The torque requirement from the motor will
vary depending on whether the roll is rolling and has inertia or not. If it had stopped and must get going from standstill, more torque, but
not necessarily more speed will be needed. Speed may need to vary as the roll of paper diminishes in weight to compensate for the changes.

There are many different types of motors on the market.

When a motor runs, the Electrical energy it consumes can be measured using a power meter, or extrapolated by using a simple AVO and Current
Probe across one of the AC supply lines. Today for under £100 you can purchase a Hall effect current probe that is electromagnetically
coupled to the AC lines so it is a reasonably safe operation.
Based on UK residential supply figures, we have 240V AC @ 50Hz. Imagine our experiment being a household vacuum cleaner being plugged into
the mains and turned on.
If we set up this experiment and the Current probe Read 8.2Amps.
Recall that Power = Current x Voltage.
Power drawn by our experimental motor = 240V x 8.2A = 1968 Watts == 2.64HP.
Note 1 HorsePower = 745.7 Electrical Watts.

Realistacally you'll probably read 1/2 of this figure. The current drawn from the mains is the easy part of discovering our the efficiency
and therefore the actual HP of the motor!

End of Digression:
Depending on your application, you have a choice of, to mention a few, the following motors; DC Motors; AC Motors; Commutator, Non Commutator, Permanent Magnet and variable-reluctance Stepper Motors.

If you type these (above) keywords with 'control', 'systems' and 'drives' into any search engine, you will find references.

Try the same with


If the application is worthy of seeking professional advice, I can recommend the engineers

Good luck!


Mark E. Ludlow

Horsepower reflects the ability to do a certain amount of work in a certain time. Imagine pulling from a roll with 550 lbf of tension at the rate of 1 ft/s. This is equivalent to 1 hp. Divide this by the mechanical efficiency of the power transmission components used and you'll arrive at the actual motor hp required to accomplish this. Multiply this number by a service factor, which depends on the severity of duty, and you will have a specification for the hp rating of components such as reducers, belts and couplings. Add another 25% if it's difficult to get to for repairs or if it's a mission-critical application.

Industrial suppliers of power transmission products are customarily quite helpful and catalogs for reducers and other power components usually have cookbook examples to follow.


Richard Norris

It doesnt take alot of horsepower to create tension on a rotating roll. The size of a motor is dictated more by the time you wish to stop it or accelerate it. The faster you wish to stop it the larger the motor. I have a spreadsheet I use for calculating this that takes into account the diameter weight core size shaft weight etc. Email me if you would like a copy at [email protected].