Mosi Li
Mosi Li

Director Project Engineer at 3Q Machining - China top CNC Machining Custom Part Manufacturer

How to Measure Roughness of a 3D-Printing Part Surface?

How to Measure Roughness of a 3D-Printing Part Surface?

Surface roughness and surface finish are two distinct properties of a 3D-printing part’s surface and there is a difference between them. Surface roughness means the variation in the surface profile across the entire surface. Surface finish refers to the uniformity of the surface texture across an entire 3D-printed object.

While measuring roughness, it is important to use a highly textured material because this will yield better accuracy when it comes to measuring roughness.

Roughness is a measure of the surface defects on a 3D-printed object. It is the evaluation of the surface defects such as removal of support material, overhangs, and undercuts. Roughness evaluation can be done by hand or with a measuring instrument such as a profilometer.

3 Ways to Determine the Perfect Surface Finish for 3D Printing Parts

3 Ways to Determine the Perfect Surface Finish for 3D Printing Parts

3D printing is turning into a ubiquitous technology. One of the advantages of this technology is that it can create any shape, which makes it versatile and attractive for many industries.

However, 3D printing still has its limitations. It’s difficult to determine the perfect surface finish for 3D printed parts without trial and error until the surface roughness value is determined first.

Surface roughness is a measure of the surface finish and is usually expressed in microns. It can vary from 0 to 4,000 microns. Depending on what you want, the desired roughness value can vary from 0 to 12,000 microns.

The end goal of 3D printing depends on how much precision you want your parts to possess. The perfect surface finish for one object might not be ideal for another object. A rough shape is considered perfect when it has a high enough surface roughness value and a low enough desired roughness value so that it creates a good layer height and bridging action.

3 Ways to Determine the Perfect Surface Finish/Roughness:

1) use a lookup table created from experimental data;

2) use an experiment with your specific printer;

3) make a rough shape and decide on the desired roughness value based on how it looks.

3 Types of Surface Roughness & How to Achieve Them with 3D Printing?

3 Types of Surface Roughness & How to Achieve Them with 3D Printing?

Surface roughness is a term that refers to surface roughness which is the quality of a material’s surface. There are different types of roughness depending on the type of finish desired.

With 3D printing, it becomes possible for the user to have the desired finishing result from a variety of materials without having to use any additional tooling or processes. The 3 types include:

  • 1) Raised Roughness: This type of finish is generally achieved by sanding and polishing. 
  • 2) Low-Roughness: This type of finish can be achieved by using chemical smoothing agents and polishing pads. 
  • 3) Medium-Roughness: This type of finish can be achieved by using chemical smoothing agents on roughened surfaces such as aluminum or glass.

surface finish chart of 3D Printing Parts

Surface Finish Chart For 3D Printing Part Design

Source: https://3faktur.com/en/the-surface-quality-of-3d-printed-parts/

The 3D printing parts can be made with any unique shapes but the geometry of the 3D part and the raw material used will determine what type of surface finishing method can be used for a specific 3D Printing part, hence the surface finish of 3D printing is combine with a technique of raw material and the 3D printer to achieved Raised Roughness / Low-Roughness / Medium-Roughness.

How do you surface finish PLA? How do you surface finish PLA?

You can 3D-printed a good quality surface finishing parts with high-end 3D printer with setting up right parameters and right raw material, but it also have other way to achieve a smoot and shinny surface finish on a 3D-Printed part by after-treatment like manual polishing, spray coating, Anodizing, Plating to remove or cover any defects on the parts’ surface; The two main methods for surface finishing PLA are adding a surface coating layer or removing defected layer by polishing.
  1. Level the Bed & Set the Z Offset: (The most fundamental way to improve the quality of a 3D print is to make sure that the bed is completely level and the nozzle is set at the optimal distance above the bed (this is known as the Z offset).

  2. Check and Test Nozzle Temperature: The temperature of the nozzle – or nozzles, if there are more than one – directly affects the appearance of the final print. If the nozzle is too hot, it could leave strings of filament between separate parts. When printing tall pieces, high temperatures or inadequate cooling can melt the earlier layers, resulting in malformation.                                 
  3. Upgrade the Build Surface: A key part of your printer that affects the materials you can print with and the surface of your printed objects is the build plate. Different build plates yield different textures on the bottom of the print: Bed materials like glass, PEI, or Kapton tape leave a smooth surface, while glue-on polycarbonate sheets or painter’s tape leave a matte finish.

  4. Keep Up with Maintenance: Each 3D printer has its own stand-out features, and probably some things that need attention to improve print quality. For example, the Ender 3s from Creality are some very popular printers that can still benefit from a few upgrades.                 

  5. Treat Filament with Care: Many filaments are hygroscopic, meaning they love water, absorbing it from the surrounding air. Exposed filament, especially ABS, nylon, and flexible materials, drink moisture in, resulting in problems.

  6. Learn Your Slicer: We couldn’t have a list of tips to improve 3D printing quality without mentioning slicers. A slicer is what converts a 3D model into the instructions (known as G-code) that drive the printer. The slicer controls the printer’s temperatures and movement, whether additions like supports or rafts are printed, and countless more factors about the printing process. Learning the possibilities of all the different settings will help improve quality, regardless of the slicer chosen.                      

  7. Add Supports: FDM 3D printers work by pushing out melted filament that bonds to the layer below it. When there’s no layer below for it to bond with, you’re essentially asking your printer to print in mid-air! If a bridge is too long or the angle of an overhang is too high, there will be sagging, or even complete failure of the print.                         

  8. Close Up Gaps: Gaps appearing in a 3D print are often related to over-extrusion or under-extrusion. A good place to start is to take a look at the flow rate (known as the Extrusion Multiplier in Cura). When changing this value, do it with very small adjustments followed by a test print with each change. Calibrating the E-steps might also resolve extrusion issues.                             

  9. Adjust Speed & Movement: The speed and movement of the print head have a clear impact on print quality. For example, after getting the first layer to stick, sometimes you might see a line where the nozzle drags across the surface or perimeter of the print. This could be caused by a lack of filament retraction.

     

  10. Post-Process Your Prints: Removing supports or getting rid of small imperfections can be accomplished with a sharp hobby knife or sandpaper, especially if painting or polishing is in order.

How can I improve my 3D print surface finish?
How can I improve my 3D print surface finish?

Sources: https://all3dp.com/2/3d-print-quality-12-tips-on-how-to-improve-it/

How do I get a smooth finish on a 3D printed part? How do I get a smooth finish on a 3D printed?
 
In generally, we are looking for a smooth surface parts, but it comes the most challenge when making parts with 3D printing, then you might wondering how we can get this done, take a close look of the steps to achieve a smooth finish on your 3D printed part then you will find out it is much easier than you might think of: 
 
01: Right Printing Method: Choose right raw material and set up right parameters of your 3D printer to your desire parts, that rely on a experience engineer whom familiar with printer and technique, you can clarify what you need then a 3D Printing Service shop can help you out for all.
 
02: Sanding Polishing: sanding polishing the 3D printed parts is simple but needs focus on details step by step from 100-200 grit sandpaper or grinder to remove stepping lines, then gradually increase up to 600 grit and 800 grit or 1200 grit and 1500 grit to achieve a smooth finish without stepping lines and any rough texture, once you finished that, the surface should be very smooth.
 
03: Surface Electric corrosion:it can be done on 3D printed metal parts that apply surface electric corrosion like EDM to achieve high end quality smooth finishing, as good as a mirror.

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