Paper shredder - does # of sheets at a time affect motor life?

Factual Questions
1

Let’s say I have a paper shredder that claims it can handle up to a dozen sheets at a time.

I have a lot of shredding to do and I would also like to maximize the life I get from the shredder.

I also notice that after I put in a stack of 4 normal 20# paper sheets the motor starts to make a weird noise and the speed of shredding slows down slightly. Seems to me that it’s working harder.

Question is: how can I tell what the sweet spot is where I can spend the least time shredding but maximize the motor life? That is, does four sheets of paper at a time have the same effect on the motor as 4 sheets at once (since in theory the motor is running for ~4x longer in one case)?

2

Start by establishing a testing laboratory for shredders. The answer can only be determined that way.

Isn’t 4 sheets at once the same four sheets of paper at a time? Or did you mean four sheets of paper one at a time?

Either way, only exhaustive testing will tell you where the sweet spot is. Less exhaustive testing will tell you if one sheet at a time works out better than four at a time.

3

Do motors draw more current when they work harder?

If they do, you could plug one of those power monitors in and watch the wattage when you shred various amount of paper and then you’d have numbers.

But that’s all you have.

I think you are going to need 16 shredders, all with those power monitors, and lots of paper.

Set four of each shredder shredding one, two, three or four sheets continuously.

Hmm, but shredders have thermal cutouts.

Go for three sheets at a time. You’ll probably be safe with that.

4

^ oops yeah that should be one sheet at a time for 4 sheets or 4 sheets at once.

5

yes, it can. Typical consumer shredders use cheap series-wound universal motors which have carbon brushed to transfer power to the motor’s armature. The more you load down the motor, the more current it draws. Drawing more current can shorten the life of the brushes/commutator.

6

You would still have no metric for wear with regards to current draw though.

Hence my 16 shredders.

Unless it’s linear, then you could probably work out the trade-off of wear versus time saved by shredding in larger batches.

Of course, the thermal cut out will probably trip more often with heavier loads, so larger batches will require longer downtime waiting for the temperature to reduce below the thermal limit sufficiently.

7

There’s always wear on the brushes, so running four times longer might increase the wear. You might be able to determine whether 4 at a time is better than 1 at a time by measuring brush wear with a small sample, but more elaborate testing is needed to find the sweet spot.

However, it is possible that the motor manufacturer has performed these tests and if the loads created in paper shredding can be related to those used in the test process you might be able to make a reasonable estimate. But it still involves testing, there no way to accurately predict this otherwise.

8

Also relevant consideration: How cost-effective is it to repair a motor thusly conked out?

If the typical failure is due to the brush/armature getting worn or burnt out: Is that an easily and cost-effectively replaced part?

Or is a broken shredder like a keyboard with one keytop broken off: You just chuck the whole thing and get a new one?

ETA: Yes, I too have noticed that all the personal shredders I’ve had will slow down noticeably with each additional sheet! Just to judge by the groaning sounds it makes with extra sheets, I’ve settled on two (2) pages as the optimal shredding capacity (just my best un-scientifically-tested guess).

ETA2: However, I don’t know all that many people, so when my personal shredder is finished shredding all the personal persons I know, I’m done with it.