A unit load is a combination of items into a single mass that can be moved as one unit. It must not exceed the size, weight, and economic constraints of the system that handles it.
1. Size constraints are determined by the minimum door openings through which the unit load must pass, the area in which the unit load will be stored, and the type of truck on which the unit load will be transported.
2. The maximum weight allowance is determined by the weakest link in the material handling system that will be transporting the unit load.
3. The economic constraint (or maximum quantity) is determined by how much inventory the company is willing to purchase and transport at one time. In most cases, companies will not purchase more than a two month supply of any item in advance of need.
There are four general considerations for the design of a unit load:
1. Materials should be assembled into a unit load at the first possible opportunity.
2. The unit load should be as large as possible without exceeding the physical limitations of the building (door heights, aisle widths, rack sizes), the material handling equipment, and the interior dimensions of the common carrier on which it will be transported between plants.
3. The unit load should minimize the number of times the product is handled.
4. The unit load should be maintained as long as possible.
In addition to the above general design considerations, there are also a variety of specific questions that must be answered in order to properly select an effective design for the unit load:
1. What is the size of the item?
2. What is the weight of the item?
3. Is the item of an unusual or irregular shape?
4. Is the item loose or is it already packaged inside a container of some type?
5. Can the items be stacked without crushing? If so, how high can they be stacked?
6. How will the items be shipped (boat, rail, or truck)?
7. Does the item require special temperature or humidity controls?
There are five basic options for creating the unit load:
1. A large self-contained unit: This type of load is feasible when the unit is exceptionally large or heavy. Examples would be automobiles, refrigerators, and washing machines. These loads are handled one item at a time.
2. Bulk containers: Used to unitize bulk materials, such as powders, granular substances, or liquids. They may be either open or closed, and are made of rubber, plastic, metal, wood, or cardboard. They may or may not be lined with a plastic interliner. Some containers are stackable and some are reusable. The most common dimensions for bulk containers are:
- Dry: 36″ cubed or 42″ cubed or 48″ cubed.
- Liquid: 55 Gallon Drum (24″ diameter, 36″ tall), or 5 Gallon Can (14″ diameter, 18″ tall), or a 1 Gallon Jug or Can.
3. Tote box or container: Any size of container that is used to transport two or more items at the same time. The items may be neatly arranged inside the container or randomly jumbled together. These containers may be made of wood, plastic, metal, wire, or cardboard. Most can be stacked. They provide a method for consolidating a lot of small parts into one unit and they also provide protection for the parts.
4. Portable rack: A frame-like structure with dimensions that correspond to the materials stored on it. The rack may or may not have wheels. A common example would be the wheeled rack used to move bread into a grocery store so it can be stacked on the store shelves.
5. Pallet: A horizontal platform used as a base for assembling, transporting, storing, and handling materials as a unit load. It usually consists of one or two flat surfaces separated by cross members. The criteria for selecting the optimal pallet size are:
- Item Size: This refers to the footprint of the item which is its width and length.
- Carrier Size: The inside dimensions of the truck, boat, or railroad box car that will be transporting the pallet load.
- Storage System: The type of material handling equipment that will be used and the width of aisles, unloading dock bays, doors, and the distance between the rack uprights in which the pallet will be stored.
Microsoft WORD Documents that correspond to this Module Assignment.
RIGHT click on the following link and download the WORD document and save the document on your computer.
1. Pallet Configurations.
Instructions for Module Assignment Three
Pallet Unit Loads
Your VISIO drawing must be done on an 8.5 inch by 11 inch sheet of paper. You must select this page size for your drawing. Your sketch will not fill up this page but it must be on this size paper. If you do not follow this instruction and you use something other than 8.5″ by 11″ then you will lose 20 points for not following instructions.
You may draw a three-dimensional sketch or you may draw three two-dimensional sketches (front, side, and top views.) Both teams members may draw the sketches the same way, or one team member may a draw three-dimensional sketch and the other team member may draw two-dimensional sketches.
Step One: The footstools are shipped one footstool per box. You must determine how large that box will be. The footstool must be put into the box with its legs on the bottom of the box and the top of the footstool facing the top of the box. Draw a simple sketch showing the exterior dimensions of each box. The box cardboard thickness is 1/8 inch on each side, bottom, and top. The wood footstool should touch the inside edges of the box. Do not allow for any packing materials. You will have two sketches, one for the standard footstools and one for the deluxe footstools.
Step Two: You must stack these boxes on a wooden pallet. All pallets are six inches high, but they have different widths and lengths. the boxed footstools must be stacked on the pallet with the footstool in its normal position with the top of the footstool inside the box facing up and the legs of the footstool in the bottom of the box facing towards the pallet. You may not stack boxes on their sides or on their ends.
Some of the following pallet sizes have been discontinued by the pallet supplier. Those sizes which are no longer available are indicated beside the pallet size. Make your selection from the sizes that are still available.
W X L X H
24 X 36 X 6
24 X 42 X 6
30 X 36 X 6
30 X 42 X 6 (Discontinued)
30 X 48 X 6
30 X 54 X 6 (Discontinued)
36 X 36 X 6
36 X 48 X 6 (Discontinued)
36 X 54 X 6
42 X 48 X 6 (Discontinued)
42 X 54 X 6
48 X 54 X 6
You may select only one pallet from the above options. That one pallet size must be used for both the standard and the deluxe footstools.
Draw two sketches, one for the standard footstools and one for the deluxe footstools. The boxes may not be stacked more than 60″ high on the 6″ pallet (total of 66″). A box may not extend more than 1″ off two opposite sides of a pallet (not adjacent sides). Show all dimensions on each sketch, and indicate how many boxes are on each pallet. Also compute the outside dimensions of the entire pallet unit load and show that data on each pallet sketch.
Divide the total volume of the pallet unit load (total maximum outside cubic inches including the pallet) by the number of boxes on the pallet and report that value on each pallet sketch (total cubic inches required per box). You will receive a higher grade if you are able to minimize this number.
Submit a “vsd” file or a “vsdx” file in the assignment folder for Module Three. Only Microsoft VISIO files will be accepted for grading.
