technology
Total Service
JUNG-ANG ENG provides a one-stop solution spanning from specialized equipment production including agitators,
heat exchangers, and storage tanks, to automation for manufacturing process facilities.
Polishing
A surface polishing process is applied to the agitator, reactor, and tank to prevent internal slurry adsorption. This polishing process is divided into mechanical polishing and electro-polishing. Unlike other companies, JUNG-ANG ENG established a polishing department when it was founded in 1987 to provide high quality in-house polishing by highly skilled employees rather than relying on outsourcing. Experience products with a completely different level of appearance from our competitors thanks to the technical skills we accumulated by producing a vast number of products.
Mechanical polishing
Mechanical polishing smooths and polishes the surface of workpieces using belts and wheels combined with various abrasive agents. This includes grinding, polishing, and buffing processes to improve product surface functionally and aesthetically. As surface defects such as grinding marks, scratches, and holes are removed, even when the work is done by skilled workers, it causes minor plastic deformation on the surface of the workpiece.
Mechanical polishing process
The mechanical polishing process consists of grinding work as a first step, polishing (abrasion) as a second step, and buffing (buff abrasion, gloss) as a third step. Polishing is a rougher abrasion process than buffing, while grinding is rougher than polishing. Grinding processes carve or bevel a metal surface using a whetstone (grinding disk). Polishing is abrasive machining by rotating an emery abrasive (glue) coated wheel made of fabric, leather, or felt at a high speed of 2,000~3,000 rpm. The surface roughness of a workpiece can be adjusted by changing the grit size of emery. Buffing is applying an abrasive using abrasive tools made of cloth or hemp and finishing the surface of workpieces to a shine. A mechanical polishing process requires experts who have several years of experience and skill.
Electro-polishing
Electro-polishing dissolves the impurities and oxide coating attached to the surface of workpieces to make a glossy surface using the dissolution of the anode. It polarizes metal to be polished and electrolyzes it with high-current density in a short time in an electrolyte to remove dirt from the metal surface and dissolve bulges, resulting in a smoother face without any foreign substance compared to mechanical polishing. Electro-polishing creates a protective coat with excellent corrosion resistance and reduces surface roughness by up to 50%. It also suppresses fatigue failure and the growth of bacteria by removing hydrogen from the metal surface and interior. The metal will have a bright and smooth gloss after electro-polishing.
Compare
| Mechanical polishing |
|---|
| Adjust surface roughness through surface grinding and polishing |
| There is residual stress and a processing deterioration layer due to the physically transformed surface. |
| Sufficient washing is required, as abrasive materials or compounds can remain from polishing. |
| Able to remove deep scratches or irregularities easily |
| Electro-polishing |
|---|
| Adjust surface roughness through surface polarization and electrochemical dissolution |
| No residual stress or processing deterioration layer, because there is no physical transformation. |
| No abrasives or compounds remain on the surface |
| Minor scratches or irregularities can be ground easily, but deep scratches or irregularities are difficult to remove with electro-polishing. |
Surface Finishing
The plate and weld bead surface finishes available at JUNG-ANG ENG are as follows.
| Stainless Steel | ||||
|---|---|---|---|---|
| NO.1 (1D) | NO.2B (2B) | HL | PL | EP |
 |
 |
 |
 |
 |
| Heat treatment and acid treatment after hot rolling | Temper rolling NO.2D that was treated by heating and acid after cold rolling | Product with a continuous polished pattern (hair-like texture) made with an abrasive of suitable grit size | Polished product with high gloss and reflectivity | Electro-polished product after polishing |
| Silver-white dull gray (no glint) | Dull gray gloss (not as glossy as a mirror) | Shining thin polished pattern | Mirror-like gloss | Gloss similar to chrome coating |
| Surface finishing for weld bead | ||||||
|---|---|---|---|---|---|---|
| Weld bead | Brush | Pickling | Grinding | Hairline | Polishing | Electro-polishing |
 |
 |
 |
 |
 |
 |
 |
Surface Roughness In Polishing Area
Surface roughness is determined by the grit size of the emery abrasive. Surface roughness may vary depending on the worker’s skill, even when products are processed through an identical method.
| Grit size | Arithmetical mean roughness (Ra) | Maximum height roughness (Ry) | Ten-point average roughness (Rz) | Root mean square roughness (Rq) | |
|---|---|---|---|---|---|
| (NO.) | Micrometer | Microinch | Micrometer | Micrometer | Microinch |
| 80 | 3.2a | 125 | 12.5s | 12.5z | 137.5 |
| 180 | 1.6a | 63 | 6.3s | 6.3z | 69.3 |
| 250 | 0.8a | 32 | 3.2s | 3.2z | 35.6 |
| 300 | 0.4a | 16 | 1.6s | 1.6z | 17.6 |
| 350 | 0.25a | 10 | 1.0s | 1.0z | 11 |
| 400 | 0.2a | 8 | 0.8s | 0.8z | 8.8 |
| 600 | 0.1a | 4 | 0.4s | 0.4z | 4.4 |
- Ra : Surface roughness is set using the average deviation of all peaks and valleys from the mean line over the sampling length of the roughness curve.
- Ry(Rmax) : Surface roughness is set using the perpendicular distance from the highest peak to the deepest valley in the sectional curve.
- Rz : Surface roughness is set using the difference between the average height of the top 5 peaks and the average depth of the bottom 5 valleys in the sectional curve.
- Rq(RMS) : Root mean square of deviations over the entire sampling length