How to Media Blast FDM Parts
The normal surface finish of FDM parts is suitable for most purposes, but in applications where a different finish is required, media blasting is an inexpensive and quick solution.
Following the best practices helps reduce the risk of damaging or breaking a part when media blasting.
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Step 1: Introduction and Materials
Media blasting can be used to achieve the final surface appearance or as a preliminary step for subsequent finishing operations. Media blasting can be used to smooth concept models, prototypes, and end-use parts. It can also be used in surface preparation for painting, electroplating, and mold masters. Blasting media is commonly rated mild to harsh based on a metal substrate.
• Aluminum oxide: harshest
Aluminum oxide is the most aggressive blast media for smoothing an FDM part and can also be used to texturize or etch parts. This media is ideal when preparing a surface for electroplating.
• Plastic: mild to harsh
For surface smoothing, this finely ground plastic media is recommended. This media is available with abrasiveness ratings from mild to harsh (Figure 2).
• Sodium bicarbonate (soda): mildest
Soda is ideal for converting a glossy finish, like that which results from a vapor smoothing operation, into a frosted, matte finish.
The same media will be more aggressive on plastics. In this tutorial, we will use plastic blast media.
What you will need:
Step 2: Prepare Your Part
Mask the areas of the part where a media blasted surface is undesirable. Masked areas may include parting surfaces of tools or sharp outside corners that could be rounded by media blasting.
Step 3: Prepare the Media Blaster
Load the desired blasting media and adjust the pressure. Start with a low pressure and gradually increase until it provides the desired results. Do not exceed 207 kPa (30 psi) as higher pressures will produce divots in the parts surface and cause the media to break down.
Step 4: Media Blast Your Part
Place the part in the blasting chamber. Position the spray gun at a 60 degree angle to the parts surface. Media blast the part using a continuous sweeping motion like you would if you were spray painting the part. To avoid damaging the part, hold the nozzle a minimum of 6 inches from the part and use several light passes across the part's surface. Do not dwell on one area.
Step 5: Remove Debris
When the desired surface has been achieved, remove debris and blast media residue.
Step 6: Conclusion
Media blasting is a simple and fast way to get a desired surface finish for your FDM printed part. Following best practices ensures a quality outcome.