FDM QUALITY GUIDELINE

Owned by Imagine That
Oct 30, 2020
2 min read

1. Dimensional Accuracy

FDM parts need to be produced within an accuracy of ±0.5 mm or 1% depending on which is greater.

For example, in the case of a 40 mm cube, a 1% accuracy requirement would result in a max of 0.4 mm deviation. As this is below 0.5 mm, the 0.5 mm is leading and determines the maximum. A printed part of 40.2 x 39.7 x 39.6 mm would be acceptable as the deviations are within this 0.5 mm. Printing a cube that is 38.8 x 39.4 x 39.4 mm would not pass the dimensional accuracy requirements as the width deviates more than 1 mm.

If you cannot meet this dimensional accuracy guideline with a certain material, the material in question might not be able to meet a customer's expectations and should not be offered.

For example, if you are not able to prevent a part from warping while printing with ABS, you should discuss with your customer and either switch to another material that is less prone to warp (such as PLA) or the order should be cancelled so your customer can switch.

This image depicts a print that meets the dimensional accuracy requirements.

 

2. Surface Quality

  • Consistent Surfaces. The final print shouldn't have any inconsistent surfaces. Retraction marks and a layer changing "seam" are acceptable.

  • No delamination. The layers should be firmly attached, resulting in a print without gaps or cracks.

  • Small details. Details larger than 0.8 mm in the model should be well discernible in the print. If details on the customer's model are (too) small, inform your customer of the result he can expect.

Please review the appendix for examples of what we consider poor surface quality.

3. Finishing/Post-processing

The customer should always be informed during the "Technical Review" step when one or more models in an order require support material and which parts of the model will have support traces. If additional costs are required, they should be added during the Technical Review step.

All support material must be removed and brought down to a level where the surface is continuous. Small traces of support material are often unavoidable and acceptable (see image).

A 150 micron PLA print showing properly removed support material.

 

Exceptions

These guidelines apply to all FDM orders