In this article, we will discuss a case for automotive parts surface deburring. This automotive part is made from magnesium alloy (specific gravity 1.80).

It has the advantage of high strength, large modulus of elasticity, good heat dissipation, good shock absorption, and greater impact load capacity than aluminum alloy.

These superior characters made it popular in automotive components.

1.   Parts condition before finishing

Material: Magnesium alloy

Appearance: The parts surface is silver color before tumbling. Some area is smooth feeling, while some other area is horny. No big burr or scale is observed with the naked eye.

Shape: This part has complex geometry. So we need to choose the right size media that not lodge in holes or recess.

Size: 108X78mm

Process before finishing: Die Casting

Process after finishing: Electro Plating

2.   Parts Surface requirement

  • Smoothing parts surface without damage parts
  • Remove the molding line from the die casting process
  • Remove the burr and oxidation layer
  • Reduce parts roughness

3.   How we process the parts

Step(1) Grinding(2) Drying
MachineVibratory Finishing Machine (without separation)Conveyor dryer or natural drying or oven
Tumbling Speed50/60HZ (full speed)
Chip TypePlastic Media TET/Cone Middle cutting
Media to Parts Ratio6:1
Compound TypeLC-13, PH 8 (mild grinding compound)
Water LevelJust cover the mass
Tumble Time1 Hour30 minutes
Notes—Manually take the parts out of the machine, and rinse themAbsorb water content and clean part surface

4.   Parts condition before and after polishing


magnesium parts before and after deburring 1
After vibratory tumbling process, you can see dark layer removed. The magnesium alloy surface formed a matte texture.



magnesium parts before and after deburring 2

You can also find the mold line is ground off and parts edge is rounded. So the parts are easy to handle and assemble for operators.

In addition, parts finished with plastic media have lower surface Ra value which means lower friction force.

5.   Other considerations

Usually, the automotive manufacturer has very huge production volume every day. They want to achieve the most possible automation level.

For the big size component, sometimes we should balance between productivity and surface quality.

The magnesium parts are heavy, so parts on media ratio need to consider. These parts can also finish with centrifugal disc finishing machine.

In that case, rotational speed has to be lower to prevent damage.


plastic media lodge in parts 1

The size of the media should choose carefully. Small size media is likely to lodge into parts hole and recess.


plastic media lodge in parts 2

To prevent lodging issue, we have to sieve out the undersized media after the process.

In the fully automatic finishing machine or continuous flow-Thu vibratory finishing system, we can design double layer sieve to collect undersized media, right size media as well as finished parts in the same step.

6.   Conclusion

In this article, we discuss a case study of magnesium parts finished with plastic media. This process can be used also for aluminum parts because they are the soft metal by natural.

Firstly, we discuss the condition of the parts before finishing.

Secondly, we show parts surface requirements from clients. Thirdly, we show the process that we did for the magnesium parts in detail.

Later, we compare the surface before and after mass finishing. At last, we discuss other possibilities for magnesium parts deburring and smoothing.

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If you have any parts to finish, please also send it to us for the finish, we will polish them and send it back to you for inspection.