Letter 10613

Zinc Plate on 12L14 Leaded Steel 

I am a large volume zinc job shop. Periodically we experience difficulty plating certain CNC parts made from 12L14(leaded steel). The process is as follows: soak clean-electroclean-2 rinses-pickle acid 25% HCL-2 rinses-condition (first rinse after plating)-plating W/alkaline-non cyanide 1.0oz/gal.zn 15oz/gal NaOH, 3 to 6 amp. per ft2 -2 post plate rinses-sour .75%HNO3-clear,yellow or black dichromate. This customer manufactures all his parts (over 200) from 12L14, but only a very few (2) won't plate the first time through the process.We have skipped the cleaners skipped the acid and we still (may) have problems with these particular parts. We have run them once, pulled them off line, let them set 2 or 3 days and replate satisfactory. All other parts, stampings, CNC W/12L14, weldmnts. cold roll, hot roll, including parts from this particular CNC customer plate OK. There does not seem to be a logical explanation to the problem. WHAT AM I MISSING??

Don Penzenik
- Elkhart, Indiana, USA

See other letters at this website for the missing information. Search at http://finishing.com/search for 12L14. You need fluoboric acid et al to activate the steel.

I believe your other parts may not have the best adhesion if all you are using is HCl.

Tom Pullizzi platronica.com Falls Township, PA

1: Degrease
2: Electroclean Reverse current (rinse)
3: HCL pickle (about 10 seconds) (rinse)
4: 20% Flouboric or sulfamic acid dip (30 sec-1 min.) (rinse)
5: Plate

Scott J. Johnston
- Grand Rapids, MN, USA

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