Chrome plated bar is the crucial material for producing hydraulic cylinders and pneumatic cylinders, so the quality of chrome plated rods directly determin the quality of hydraulic cylinder and pneumatic cylinders.
Then what should we do to ensure the quality of Chrome Plated bars? what should we pay attention to during chrome rod production?
Here below are the key points to ensure the quality of the hard chrome plated shafts.
1. Use high quality raw materials.
The raw materials for chrome palted rods / chrome plated bars /hard chrome plated shafts are round steel bar. There are many different steel makers in China, some are with good quality, but some small factories are with poor quality. We need to use steel rods /steel round bar made from the high quality factories, such as Baosteel, TPCO, SHA STEEL, Xinye Steel and so on.
2. Inspect the surface quality before grinding
The outer surface quality requirements of the chrome plated bar are relatively high, so before start grinding, we need to inspect the surface quality. The defects such as Cracks, deep scratches and pits should be repaired or removed from the steel rods.
3. Ensure the dimension tolerance of the diameter
During grinding and polishing process, the workers need to inspect the dimensions of each steel bar to ensure the diameter dimension is correct and within the tolerance.
4. Suitable heat treatment process.
The heat treatment process is very important to hard chrome plated bars. Normally the chrome plated bars are supplied with a certain heat treatment process. The heat treatment will provide the chrome plated rod with higher strenght, high hardness and lower residual Stress. There are 3 main heat treatment process for chrome plated steel bar as below.
- Quenching and tempering heat treatment
Q&T treatment is the most popular heat treatment for hard chrome plated rods, most of the materials of chromed rods such as CK45 chromed rod, 1045 chrome rod, 4140, 27SiMn can be Q&T heat treated.
- Induction hardened heat treatment
Induction hardened heat treatment usually is applied to get higher hardnen for the piston rods, chrome plated bar with this kind of heat treatment is known as induction hardened chrome plated bar.
- Q&T treatment and induction hardened
The heat treament is applied before chrome plating, and some customers maybe not require the steel rods heat treated for some low requirement applications, in this case they can save some cost.
5. Control the quality of Hard Chrome Plating
Hard chrome plating is an electroplating process in which chromium is deposited from a chromic acid solution. Thickness of hard chrome plating ranges from 2 to 250µm. The hard chrome plating thickness provides good surface hardness of the rod and can provide good resistance to corrosion. So it is very important to control the good hard chrome plating quality of the chrome plated bar.
6. Polishing after chrome plating
After chrome plating, the hard chrome plated rods will be polished to get a super smooth surface with roughness below Ra 0.4μm (usually around Ra 0.2μm).
7. Perform reliable packing to protect the chrome plated rods during transportation.
The outer surface of the chrome plate rods need to be well protected from any damaging such as scratching, pits and so on which caused during transportation.