|Wasted effort: Box at same level as materials
|Wasted effort: Materials lower than bags
Packing stations often involve needless motions that can often be eliminated by paying attention to heights of the items relative to each other. These unnecessary shoulder and hand motions can waste a considerable portion of the packing work cycle and can increase the risk for musculoskeletal disorders. In the case of packing heavy items, there can be considerable exertion and strain on the joints. Sometimes, the extra handling can also lead to product damage.
Additional issues at packing workstations include the location of box flats or packing materials and the use of tape and label dispensers, which similarly can involve awkward heights and unnecessary motions.
Issues and Options
|Waterfall concept to reduce time and motions
The waterfall concept provides a good general strategy for packing stations. Typically, the top of the bag or box should be at the same height as the incoming material. The advantages are:
- Replacing an up-and-down arm motion with a simpler downward motion
- Increases the possibility of sliding materials, rather than picking them up and putting them down
- Takes advantage of gravity
Automatic packing stations invariably use the waterfall concept because it is too complicated and expensive to mechanically lift up and put down. The same approach is good for humans too.
|Good set-up at bagging machine
|Funnels reduce motions
Bagging machines are common and provide advantages over the manual methods described below. However, attention must still be given to the set-up and height relationships to apply the waterfall concept.
The top of the bagging machine often provides a natural place to put the parts to be packed. A funnel can be incorporated to feed the parts directly into the bag, allowing the packer to simply slide the material rather than wasting time and motions to pick up and put down the items.
|Home made stand for roll of bags
|Sketch of how to add surface to incorporate waterfall concept
Bags can be purchased in rolls and mounted on stands. Incoming parts should generally be at the height of the bag opening, as shown in the sketch above.
|Air jet (blue tube with orange tip)
Air jets are commonly integrated into bagging stations to automatically open the bags. They can be used in both manual and machine bagging systems.
Elevated incoming surface
|Retrofitted elevated surface
The photo above shows how incoming materials can be fed in a packing station at a height that permits packing into boxes with minimal effort. The shipping box is not shown in position in this photo, but the top of the box is slightly lower than the elevated surface.
Tipping box stand
|Packing stand puts top of shipping box level with incoming materials
|Tipper enables the box to slide to takeaway conveyor (below incoming conveyor)
This packing station (for frozen hamburger patties) shows a number of ideal features. The box stand is designed for a height that places top of shipping box slightly below the height of the items to be packed. Thus, the packers can sweep the product into the box with the left hand, guiding the product with the right hand with minimal pick-and-place motions.
When the box is full, the packer activates a tipper under the box stand, which enables the box to slide down to the takeaway conveyor. Thus, it is not necessary to lift the full box. The takeaway conveyor is under the main delivery conveyor, which saves floor space and enables the use of gravity to move the box.
Note that the workstation is oriented so that the employee stands with the conveyor at the side (shoulders perpendicular to the conveyor). In this particular situation, this orientation reduces reach compared to standing facing the conveyor (shoulders parallel to the conveyor) and reaching across the shipping box.
|Another example of lowered box stand (right, without boxes for clear view)
The workstation above incorporates a packing station at the outfeed end of a machine. Once again, the box top is at the same level as the surface of the incoming parts. Note in the left photo above that the box flap is tucked under the outfeed surface.
|Slanted orientation for tote of incoming materials
A final variant of a packing station that shows good height relationships incorporates a notched, slanted surface for a tote. For some types of items, it is possible to slide the tote directly over the box and dump the product. In other cases, the products are picked up and placed in the box, with minimal motions. The diagonal orientation for the tote helps use gravity to bring the products as close as possible to the box.
Note the over-and-under conveyor on the right side of the photo. The tote is brought to the packer on the upper level. The filled shipping box is pushed forward onto the lower takeaway conveyor.
Slanted box stands
It is common for the shipping box to be placed on a slanted surface, which makes access easier and reduces the reach. Slanted box stands are particularly helpful for large boxes and/or heavy items. See also parts handling.
|Highly adjustable box stand
|Mobile box stand
Slanted box stands are commercially available and can be used in assembly areas for staging parts as well as in packing stations.
|Slanted for packing
|Tipped for takeaway
A box stand can be designed with a hinge so that when full, it can be tipped to roll onto the takeaway conveyor. In the “horizontal” position, the stand is actually slanted slightly down towards the conveyor, to take advantage of gravity.
|Powered cylinder for tipping
This example incorporates a power cylinder. Additionally, it tips a full 90 degrees.
|Before: High lift (and twisting of back)
|After: Box stand places tall box at slant adjacent to conveyor, allowing product to be slid into open box.
This example shows how a large box stand can be incorporated into the conveyor line. The “before” work area required the packer to pick up the product from the conveyor, lift it to head height, turn 180°, and place into the shipping box. The “after” photos show how the product is slid into the shipping box without needing to lift, thus saving time and motions.
Multiple packing levels
|Up position for tall boxes
|Down position for medium boxes
|Drop down shelf
It is common for packers to use multiple size boxes, some considerably larger that others. In these instances, it can be helpful to design for multiple heights. The example above shows a drop down surface that permits packing into either a tall box or a medium-sized box. See height adjustment
Miscellaneous related issues
Packing material location
|Poor: Packing paper roll to side
|Good: Packing paper directly over box
|Automatic packing dispensers reduce arm motions
Cardboard flat staging
|Horizontal storage creates high reaches (and low bends)
|Vertical storage reduces high reaches
|Vertical storage on floor reduces low bends
Optimal staging of box flats can be problematic, especially if many different sizes are needed close at hand. However, a good rule of thumb that can help in many cases is to orient the flats vertically rather than horizontally. This simple trick can reduce high reaches and low bends. See work area storage.
|Copper tubing box clip
Box forming machines
|Manual box forming
|Automatic box former (www.lantech.com)
Folding boxes manually can create strain on the hands and wrists. Often it is possible for suppliers of the box flats to mark or score the cardboard to facilitate bending.
However, sometimes the best solution for situations where there is high volume use of the same size box is to use a box forming machine. There are many such machines commercially available. The feasibility depends greatly on the type of box and the volume of use.
|Problems: Poor knee clearance; arms raised to reach
All the standard issues for workstations apply to packing stations. In the above example, the plastic safety guard around the bagging machine is too large and conflicts with the knees, which also makes it difficult to raise the chair to a better working height.
Lifting materials to packing station
|Prep work at same level as bagging
|Prep work lower than bagger
In order to incorporate the waterfall concept, the incoming materials need to be higher than the point of operation for packing. Above left, the preparatory work is done on the same table as packing, which then requires each item to be lifted up in order to place in the bag. Above right, the preparatory work is actually lower than the bagging height. In both cases, the prep work should be done at a higher level, or some other improvement made to eliminate the manual upward lift.
|Inclined conveyor at packing station
Inclined conveyors provide a technique to bring items up to a good height for packing. See conveyors