Plan Container Packing From an STL Part File

Short answer: Export the part as an STL file in millimetres. Import it, check its dimensions and up direction, and set the gaps, orientations and part weight. Then calculate the arranged packing in two to four candidate containers and compare the packed quantity, layers and space use in 3D.

An STL file describes the outer surface of a part as triangles. Most CAD systems can export it. This guide shows the steps in Optipacker and the checks to do before you trust a result.

1. Export the STL file

• Export one part for each file, in its finished state.
• Use millimetres. If your CAD system exports inches, record that. A wrong unit makes the part 25.4 times too small or too large.
• Use a moderate mesh resolution. The packing calculation uses the part's dimensions, so a very fine mesh adds file size and no accuracy.

2. Import the part and check its dimensions

Optipacker reads the length, width and height from the STL file. Compare them with the drawing. Check which side is up, because the up direction decides which faces can rest on the container floor.

If you have no CAD file, enter the dimensions by hand. You can also take one to three photos for an AI dimension estimate. Verify an estimate before you plan a tight fit.

3. Add the data that limits the result

• Part weight: without it, the result cannot check the container's weight limit.
• Allowed orientations: restrict rotations if the part must stay upright or rest on a given face.
• Gaps and clearances: set the space between parts and to the container walls. Inserts and handling need this space.
• Annual volume: you need it later for the number of containers and the investment.

4. Choose candidate containers

Pick two to four containers that you can buy or already use, for example a small load carrier, a returnable box from your pool and a cardboard box. Optipacker has a container library with standard templates, and your organization can add its own containers.

5. Calculate the arranged packing

Arranged packing calculates the position and rotation of each part, layer by layer. Review each layer in 3D and check that the parts sit as your operators will place them. If the parts go into the container loose, use a bulk estimate instead. A bulk estimate gives a capacity without part positions.

6. Compare the containers

Compare the packed quantity, the number of layers, the weight and the space use for each container. The container with the most parts is not always the best choice. It can need a heavier insert, exceed a lifting limit or fit badly on a pallet.

Know what the calculation assumes

Optipacker's project packing places each part as its bounding box: the smallest rectangular box around the part in the chosen orientation. For blocky parts, the result is close to the real limit. For L-shaped, hollow or angled parts, packing by the real shape can fit more. In our measurements at 5 mm gaps, an open bracket model fitted about 31 % more parts by shape, and two slim parts gained 0 to 3 %. Read the full measurements.

Try it

Use Quick Plan without an account. It accepts an STL file of up to 2 MB and 10,000 triangles. You can also open the interactive packing example or ask for a demo with your own parts. To see how other tools use part geometry, read the comparison of packaging planning software.