Bulk Bag Filling Rate Guide

Every filling machine requires an operator to physically rig the bulk bag, initiate the fill sequence, tie-off the filled bag, and to initiate bag removal. Some filling machine models, however, lend themselves more readily than others to automation.

The output of filled bulk bags from the selected bulk bag filling machine has to be determined. This output is governed by the time it takes to fill the bulk bags. This period can be divided into two categories: Fixed Time and Variable Time.

Table 1 below shows task duration times for a forklift removal bulk bag filler.

 *Only loose, tubular liners need to be inflated.  If you are using this type of liner add 15 seconds to the overhead time. 

**See the fast fill chart below.  Add the appropriate fast fill time to the total overhead time to determine bagging rate.

Table 2 below shows task duration times for an automatic bag removal (ABR) bulk bag filler.

*Only loose, tubular liners need to be inflated.  If you are using this type of liner add 10 seconds to the overhead time. 

**See the fast fill chart below.  Add the appropriate fast fill time to the total overhead time to determine bagging rate. 

***The inlet spout is typically tied off outside of the filling machine while the next bag is being filled thereby reducing overhead time and increasing the bagging rate.

Bag Filling Rate

Two factors have to be considered to determine the bulk bagging rate of a system:

1. Bulk transfer rate of product to the bulk bagging location
2. Instantaneous feed rate required to fill the bag

The first parameter is easily determined.  If you want to fill 10 - one short ton bags per hour, your bulk transfer rate to the bulk bagger must 20,000 lb/hr (10 bph x 2000 lb/bag = 20,000 lb/hr).

However, the manner in which the product is fed into the bag must be carefully considered.  Referring to the above charts, note that the fast fill time is a critical component of the overall bag filling time.

Table 3 below is based on a fast fill weight of 1,950 lb.  That means that we want to fill 1,950 lb into the bag as fast as we can and then dribble feed the remaining 50 lb over a 15 second period to ensure accurate weighing.

The table shows the required instantaneous feed rate and fast fill time for various bagging rates for both a forklift bag removal filler and an automatic bag removal filler.

Note that the instantaneous fill rate can be extremely high.  That's why bulk bag filling systems above 10 bags/hr are typically fed by gravity from a silo or surge hopper sized to contain the amount of product fed to the station by the bulk transfer system during the overhead time period.

Note that the forklift bag removal column ends at 15 bags/hr.  This reflects the typical break point after which moving bags by forklift becomes inefficient relative to the round trip distance from filler to loading dock or warehouse storage location.