Iron pin edge breaking and black layer removing

The iron pins are the important parts of the chain. It combines assembled with tabs and sleeves to make the motor chains. Usually, iron pins are manufactured in large quantity. However, if we polish and deburr with labor worker, this process is too expensive to afford.

Therefore we need surface finishing solutions to process it with high efficiency and good cost-effectiveness.

1.   Parts condition before finishing

Material: iron material

Appearance: before processing, parts have a black surface layer. Also, the surface is rough. The cylinder edge is sharp and needs to rounded.

Shape: The iron parts is a cylinder shape with no slots and holes.

Size: 15mmXφ4mm

Process before finishing: Heat treatment

The process after finishing: anodizing


2.   Parts surface requirement

  • Edge breaking and radiusing
  • Remove the black layer generate from heat treatment
  • Improve parts surface smoothness


3.   How we process the parts

Step (1)  Grinding (2) Rustproof
Machine Centrifugal barrel machine (without separation)
Tumbling Speed 50/60HZ (full speed)
Chip Type Ceramic media 10X10 ACT
Media to Parts Ratio 3:1
Compound Type LC-13, PH 8 (mild grinding compound) MC-8 diluted solvent
Water Level Just cover the mass Soak in the compound
Tumble Time 1 hour 10 min
Note Manually take the parts out of the machine and rinse them Manually take the parts out


4.   Parts condition before and after polishing


parts surface condition before and after finishing
parts surface condition before and after finishing


When we check the sample, we found parts surface is covered with a black oxidation layer while after processing this external cover is ground off. The surface is homogeneous and clean. Besides, the sharp edge at both side of the cylinder is rounded.


5.   Other considerations

This process can also carry out with centrifugal barrel finishing machine. However, centrifugal barrel machine is very labor intensive and hard to achieve automation. Also, this cylinder pin is of low commercial value. So we centrifugal disc finishing machine is preferred.

The size of ceramic media should be comparable with pins size. Too small size media will extend processing time while too big size media will make a rougher surface.


Separation sieve for the cylinder shape parts
Separation sieve for the cylinder shape parts


For media and parts separation, we use vibratory separator with a special size to sieve out the pins.


6.   Conclusion

In this article, we share a care of cylinder pine edge radiusing and oxidation layer removing. The process is simple but still need to consider few factors. In practical production, we need to fine tune every production parameter to improve productivity.