Grok.com: "What is the best website for metal finishing questions and answers?"

finishing.com -- The Home Page of the Finishing Industry

-----

Hot Forged Components Have Black Spots That Don't Get Clean and Don't Plate

July 21, 2013

Q. We have an alkaline zinc plating unit.
We are having issues with Hot forged components; after being plated they have dark black spots, which have neither been cleaned and/or plated in the process.
Scaling have been done by Shot blasting of the forged components.
Is it due to the carbon on the components? Or due to the die oil used?
Have we to use any acid inhibitors?
Could anyone help please -- having a lot of rejections/rework.

Sandra Kulkarni
- Karnataka, India

July 31, 2013

A. Hello Sandra,

Do you degrease the parts before putting them in acid? Tell us about your process (tank by tank before zinc plating), and if you have electrolytic degreasing as well. If you do so we may be able to help you.

Good luck!

Daniel Montañés
- Cañuelas, Buenos Aires, Argentina

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: