In this article, we will discuss plastic coil frame material cleaning and polishing. This plastic part is made from epoxy resin which is the soft material.
1. Parts condition before finishing
Material: Epoxy plastic material
Appearance: before processing, the surface of the entire parts are covered with dirt
Shape: The plastic coil frame has a very simple geometry. However, the part has small slots so that very small wear debris or granule will lodge in.
Size: 46mm (diameter) X17mm (height)
Process before finishing: NA
Process after finishing: Assembling
2. Parts Surface requirement
- Smoothing parts surface without damage parts
- Media does not get stuck at parts slots and holts
- Remove the black layer generate from the die casting process
- The surface is mirror shining and ready for assembly
3. How we process the parts
|Step||(1) Polishing and cleaning||(2) Drying|
|Machine||The centrifugal disc finishing machine||Natural drying|
|Tumbling Speed||50/60HZ (full speed)|
|Chip Type||Angle cut triangle super fine porcelain|
|Media to Parts Ratio||3:1|
|Compound Type||LC-13, PH 8 (mild grinding compound)|
|Water Level||Just cover the mass|
|Tumble Time||30 minutes|
|Notes—||Manually take the parts out the machines and rinse them|
4. Parts condition before and after polishing
The epoxy parts after long time storage become dirty. So we want to use the mass finishing process to make it clean.
When we have a close look of the parts, the new part is clean as a new one. The surface is clean and smooth.
5. Other considerations
We have tried a different material for the plastic parts cleaning and polishing.
Firstly, we tried walnut shell, because it is a softer natural material. Since it has no cutting power, therefore, is able to clean parts surface without damage. However, walnut shell granulate tend to lodge in the plastic holes.
Walnut shell can give a good surface cleaning, but the particles fit well inside the slot. And it’s hard to take out one by one. Therefore we have to think about the new way.
Also, we have been thinking about using plastic tumbling media. However, the plastic tumbling media is polyester based material which is harder than epoxy. So the surface will wear out if we choose plastic media. So the only media that we can choose is non-abrasive porcelain media.
But what size and shape to choose?
We have tried several options.
Firstly, we try with zirconia ball. 2mm ball allows it to enter all surface but it cannot polish the inner side of the parts even after 1 hour in centrifugal disc finishing machine. Then we are thinking if we can use a “long” media.
On the second try, we use fine porcelain cylinder media with size 2.5X8mm. This media performance much better than the ball media, but still slow to remove the inner side of the parts.
On the third try, we use fine porcelain media with angle cut triangle shape 6X6mm. This media can reach deeper parts’ surface and also have some cutting power. In 30 minutes, the surface of the entire parts has become white and clean.
In this article, we give an example of epoxy plastic parts cleaning and polishing with different media. We have success in superfine porcelain media with triangle shape after several trials.
Firstly, we discuss the parts condition before finishing. Secondly, we show parts surface requirement from clients. Thirdly, we show the process that we did for the plastic parts in details. Later, we compare the surface before and after mass finishing. At last, we discuss the process how we select the media and different media that we trials in the process.