Why do Over/Under runs vary by so much?

Overruns and underruns are one of the most misunderstood part of the manufacturing process. It's tempting to look at it similarly to printing copies on your desktop printer. If you need 200 copies, you print 200 copies. Manufacturing isn't quite as simple, and adds some unknowns into the equation. 

In a manufacturing environment, overruns and underruns are quite common. There are three main steps in making bags - blowing the film, printing the film, and converting it into individual bags. All three of those steps require setup which creates waste. For instance, to produce 20,000 bags, we need to have enough printed film to cut those bags, plus some extra to set up the job, and in case of misprints that are discarded at this step. So we need to print quite a few more than 20,000 impressions. To print enough film for any given job, we need extra blank film in order to set up the printing press. So we need to blow enough extra film to account for printing setup, converting setup, and possible misprints. The raw material for the film is in pellets of plastic resin that are weighed out in an amount that is approximately enough to make enough bags, plus a little bit. Extruding the film can also result in small variances in bag width and thickness, which also affects overruns. 

So making an exact number of bags is nearly impossible, and the over/under run percentage is not predictable. 

Information about our overrun policy is on our terms and conditions page. https://www.apmbags.com/terms-and-conditions