1. State the purpose of the gas channel

Identify whether the channel is intended to hollow a substantial section, support packing near a problem area, or contribute to a structural layout. Mark the cosmetic face, attachment points and regions that must remain solid. This makes it possible to judge the design against a specific outcome rather than maximum hollowing alone.

2. Design the gas path with the melt fill pattern

Gas follows the easier flow path, so a visually symmetric branch does not guarantee equal penetration. Review the channel layout alongside gate location, wall transitions and the areas expected to fill last. Changes to one can change the others.

A channel can also influence plastic flow before gas enters. Avoid treating it as an isolated hollow feature added after the rest of the part is complete. SPE design discussion by Hank Tsai

3. Check channel geometry and the surrounding wall

A gas channel is a preferred gas path within the polymer, often associated with a thicker rib or section. The adjacent wall must also be evaluated: gas should not penetrate into unintended regions or break through the surface. Geometry and the quality of its simulation representation influence how well the gas path can be predicted. Autodesk gas-channel modeling guidance

Review turns, transitions, junctions and the ends of channels explicitly. A dimension that works in a straight region should not be assumed to give the same remaining wall elsewhere.

4. Locate plastic gates and gas inlets together

Ask how the proposed gas entry points relate to melt flow and the intended penetration length. Evaluate gas timing and process conditions alongside location. A gas-inlet position should be justified by the part and process, not selected only because there is physical space in the tool. Moldex3D GAIM evaluation topics

5. Review the internal shape, not only the outside

The actual hollow region can differ from an idealized CAD tube. Its shape and position affect the structure. For load-bearing features, define how the internal geometry will be represented in analysis and checked in samples. BASF’s published development work illustrates why the predicted gas-cavity shape can matter to structural evaluation. BASF technical example

Unwanted finger-like branches of gas can extend outside the intended channel. Severe fingering may weaken a part; it should not be accepted simply because the exterior looks satisfactory. Moldex3D explanation of gas fingering

6. Agree the evidence needed for approval

Prepare a project-specific review list:

• Which dimensions and surfaces control acceptance?
• Where does remaining wall thickness need to be checked?
• Which loads or assembly conditions need testing?
• Which resin grade and processing assumptions apply?
• What sample and process records are required?
• Who approves changes to the geometry, material or tool?

Select the inspection or test method to suit the feature and requirement. Agree the criteria before trial results arrive.

Bring the design questions into development

Use this checklist with gas assist injection mold development. For the basic sequence, read what gas assisted injection molding is. To discuss your part, send the available project information.