The beauty of additive manufacturing (AM) is the ability to go directly from a CAD model to a physical part, which is great for prototyping. However, production parts made under any proper design and manufacturing process require information beyond the CAD model.
The documentation effort for AM is less than most traditional manufacturing processes, but drawings and specifications are still necessary. Manufacturing needs to know what processes to use, acceptable tolerances, post processing and how to mark and store the part. The purpose of part documentation, usually in the form of a drawing, is to tell manufacturing and quality what the correct part is. The CAD geometry usually only contains the geometry so non-graphical attributes need to be placed on the drawing, in notes or in specifications.
Engineering should develop drawing standards for parts made using additive manufacturing that define what information needs to be included on any drawings. These standards should be reviewed with manufacturing and quality control to make sure they contain all of the information that both departments need.
Eric Miller of PADT Inc. also provided Digital Engineering with an Additive Manufactured Documentation Checklist:
- Material specification
- Orientation in the machine
- Support parameters
- Machine build parameters or acceptable ranges
- Support removal requirements
- Part cleaning
- Final curing
- Sanding/grit blasting
- Heat Treat
- Storage constraints (temp, humidity, etc.)
- Surface finish
- Dimensions and tolerances
- Acceptable warping/distortion
- Features that require secondary machining
- Part marking
An important related documentation requirement is to keep the build file used by the 3D printer. Every 3D printing method involves taking a solid model and turning it into a set of instructions that specify the layer-by-layer building process; in essence, the toolpath for the machine. This file should be stored and controlled like any set of machine instructions to ensure repeatability.
>>Read more by Eric Miller, Design Engineering, November 1, 2016