 |
 |
Hard Chrome Plating Training Course
Appendix 3. Reverse Etch Times
Reverse Etch Times
This table presents reverse etch times for various metals that are commonly hard chrome plated.
Reverse times are given for etching outside diameters at a current density of 3.0 APSI for:
- stick anodes at an anode to cathode distance of 6 inches, and
- conforming anodes at an anode to cathode distance of 0.75 inches.
For inside diameters or flat surfaces, subtract 15% from the times shown.
Unless otherwise indicated, the times below are for reverse etching in a standard 33 oz/gal hard chrome bath, with a maximum sulfate concentration of 1 oz/gal and operated at 135°F.
Other settings can be used, but any differences should be taken into account. For example, using a higher current density and/or closer anode to cathode spacing will decrease the time needed for reverse etching.
The optimal reverse etch time for any particular setup and bath may vary considerably from the values below due to many factors including those related to the anodes, bath chemistry and the condition of the part. It is recommended that until an optimal time is established through testing, that the plater check the progress of etching after 50% of the recommended time (desired condition is a grey mat appearance).
Metal Type (AISI) |
Stick Anodes at 6 inch Distance Reverse Etch Time (minutes: seconds) |
Conforming Anodes at 0.75 inch Distance Reverse Etch Time (minutes: seconds) |
| Standard Steels | ||
| 1005 - 1039 | 5:00 | 2:30 |
| 1040 - 1060 | 3:00 | 1:30 |
| 1064 - 1095 | 1:30 | 0:45 |
| 1108 - 1119 | 5:00 | 2:30 |
| 1132 - 1151 | 3:00 | 1:30 |
| 1211 - 1215 | 5:00 | 2:30 |
| 1330 - 1345 | 2:00 | 1:00 |
| 1513 - 1527 | 5:00 | 2:30 |
| 1536 - 1572 | 2:00 | 1:00 |
| Alloy Steels | ||
| 4012 - 4028 | 3:00 | 1:30 |
| 4037- 4047 | 2:00 | 1:00 |
| 4118 - 4161 | 1:00 | 0:30 |
| 4320 - 4340 | 1:00 | 0:30 |
| 4419 | 3:00 | 1:30 |
| 4615 - 4626 | 2:00 | 1:00 |
| 4718 - 4720 | 2:00 | 1:00 |
| 5132 - 5160 | 1:00 | 0:30 |
| 8720 | 2:00 | 1:00 |
| Stainless Steels* | ||
| 201 - 304 | 1:00 | 0:30 |
| 305 | 1:00 | 0:30 |
| 308 | 1:30 | 0:45 |
| 310 | 0:45 | 0:24 |
| 316 | 1:30 | 0:45 |
| 316L | 2:00 | 1:00 |
| Magnetic Stainless Steels | ||
| 403 - 416 | 1:30 | 0:45 |
| 440 | 0:45 | 0:24 |
| 501 - 502 | 2:00 | 1:00 |
| High Temperature, High Strength Steels | ||
| 601 | 1:00 | 0:30 |
| 602 - 604 | 2:00 | 1:00 |
| 610 - 616 | 1:00 | 0:30 |
| 630 - 650 | 2:00 | 1:00 |
| 651 - 652 | 0:45 | 0:24 |
| Other | ||
| Cast Iron Grey | 0:05 | 0:05 |
| Cast Iron Chilled | 0:30 | 0:15 |
| Cast Iron Malleable | 0:40 | 0:20 |
| Copper | 0:00 | 0:00 |
| Brass | 0:00 to 0:15 | 0:00 to 0:15 |
| Zinc | 0:00 | 0:00 |
* Etch in sulfuric/hydrofluoric acid tank.
 |
 |
 |
The information contained in this site is provided for your review and convenience. It is not intended to provide legal advice with respect to any federal, state, or local regulation.
You should consult with legal counsel and appropriate authorities before interpreting any regulations or undertaking any specific course of action.
Please note that many of the regulatory discussions on STERC refer to federal regulations. In many cases, states or local governments have promulgated relevant rules and standards
that are different and/or more stringent than the federal regulations. Therefore, to assure full compliance, you should investigate and comply with all applicable federal, state and local regulations.