HP MJF Part Wear / MJF Part Strength Examples

At Forerunner 3D Printing we currently producing HP MJF 3D Printed Parts that are made out of Nylon PA-12. They feel strong when handled, and the material spec sheet from HP says they are strong as well. We have had early success with using them in high load applications that required them to be strong however, we needed to produce our own evidence of MJF part strength as well as MJF part wear resistance in order to convince some of our customers of its viability in their applications. In order to accomplish this we handed the parts over to our sister company DeWys Engineering, and they designed a few tests that could show the true strength of MJF 3D Printed parts in various scenarios. The following are our independent testing results based on real world applications we have considered using MJF 3D Printed parts for. We plan to continue updating this page as more of our testing is completed. If you have a specific application you would like to see tested, let us know we would love to talk with you about it.

 



MJF Part Wear Testing: 3D printed nesting application

We have seen quite a bit of interest from various machine builders we work with around using MJF components as nesting details for holding components in place while they are assembled on automated / manual factory equipment. After presenting them with example nests the first questions that they asked was “how wear resistant is this Nylon PA-12 material”? Handing them a spec sheet and telling them to trust us was not going to cut it. The next step for us was to do some testing to prove out its wear resistance and that it could hold up to abuse as well as a traditional nesting that was machined out of Delrin or Nylon.

HP MJF Part Wear / MJF Part Strength - Test rig explanation picture

A purpose built MJF wear tester was constructed and the following test was run:

  1. Pneumatic air cylinder: The cylinder was hooked up to a 90PSI air source and was able to develop 100 LBS of force on its extend stroke as it drove the aluminum block into the nest.
  2. MJF 3D Printed nest: Was bolted onto the base plate and had a .755″ wide slot that was meant to nest the aluminum block
  3. Aluminum block: Built to be .75″ wide, this detail is meant to simulate a part that is being repeatedly inserted into the MJF nest, over time it will likely cause the MJF part to wear
  4. .010″ shim stock: This is meant to cause a misalignment between the aluminum block and the MJF nest it is going to be placed in repeatedly, the hope is this will cause a wear condition
  5. Cylinder stroke counter: keeps track of how many times the Aluminum block has been inserted into the MJF nest detail

 

 

After 100,000 cycles the block was removed from the test bench and 3D Laser scanned, an inspection report was then produced. The full report can be viewed here. Below are the highlights:

The end result of the testing was that the block showed some signs of highly localized wear up to .011″ but overall the MJF part wear was not as extensive as was originally anticipated. As a result, Forerunner 3D Printing is now producing nesting details for several of our machine build clients on our HP Multi Jet Fusion 4200 3D Printer in Nylon PA-12.

 



MJF Part Strength Testing: 3D printed thread / part tensile strength

One of the first questions we got from a potential customer was “how well do these 3D printed parts hold threads under tensile loading”, we did not have a good answer for them so we decided to find out! This testing also dovetailed nicely into a broader question around MJF part strength in general so we combined the two. We printed 1/4″-20, 3/8″-16. and 1/2″-13 test bars with threaded holes in either end. We then printed corresponding MJF eye bolts with the appropriate thread size on them. After putting them together we placed them in out tensile testing rig and gave them a pull! Here are the results:

 

The breaking point for each sample was:

1/4″-20 = 211 LBS

3/8″-16 = 345 LBS

1/2″-13 = +650 LBS (part did not break, threads showed no sign of elongation or binding after test)

The end result of this testing was the finding that MJF part strength in tension (this is the weakest direction for 3D printed parts) was much higher then initially anticipated and also that holes with threads printed directly in them have the ability to not only hold a fastener but do very well in high load applications!

 



MJF Sonic Welding Insert Test & Pull Out Strength

 

 

 



MJF Part Wear Testing: 3D printed End of Arm Tooling Grippers

Coming Soon!



Click here to go to the 3D Printing Machines & Materials page


Have questions?

Contact us:

Sales@Forerunner3d.com – 231.722.1144

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US Government CAGE Code: 805Z7

Locally owned and operated from Coopersville Michigan.

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