Hard chrome plating thickness required for different applications?

A. Hi Jim. Colors can be deceptive in photos, but it looks to me like the chrome is chipped off in that area. Is it possible to get a more detailed close-up view, or some other way to know if the chrome is missing there?

The glass bead blasting is the only prep (no cleaning or activation)? Do you send the parts out for plating or do it in house?

Luck & Regards,

A. Hi again. The issue of course is that the problem might be on your end or it might be on the plater's end. The plating shop surely has to re-clean and activate the parts after their travels by truck, and we have no information at all about what they are doing for inspection, cleaning, activation, etching, plating, and re-inspection.

Based only on the pictures I continue to believe that the plating is chipped/flaked away. The hints that lead me to think that are the color and the shape. Shapes which have something to do with wet processing will generally have somewhat rounded shapes because liquids have surface tension. Due to surface tension & viscosity, drips and stains don't have sharp knife-edge points like this defect. Chips and flakes may have sharp edges.

0.0002" to 0.003" might be enough just to catch a fingernail on, or a close-up photo at 90° to this photo might verify the absence of plating.

Luck & Regards,

A. Hi, Michael. "Flash" just means a very thin or very quick coating and has no real quantitative meaning. Thin Dense Chrome is a trade name for a proprietary; some experts think quite highly of it while others are less impressed. You should talk to the purveyors and ask what the quantitative differences are, then talk to the doubters and decide for yourself how significant the technology is for your particular needs.

While the thickness of chrome has some effect on its corrosion resistance, the reason you specify a particular thickness usually doesn't have much to do with corrosion resistance but with wear life and providing enough thickness to develop hardness on the substrate in question if necessary. On a very hard substrate, a couple of ten thousandths of an inch may provide good wear resistance; but on a soft substrate you may need several thousandths before you have anything truly useable. If your molds are copper for example, your 0.006 to 0.01 inch is probably not excessive. But if they are hard steel (which I suppose they are because you worry about rust), I suspect that the 0.001 to 0.0015 might well do it.

Hopefully we'll hear from an experienced mold plater. Good luck.

A. I also think your specified thickness is excessive. Some tool designers tend to think that a thicker coating is better, but this is not always right. Besides what Ted pointed out, there's another issue with heavy electroplated coatings when applied to molds or tools: profile distortion. Thin dense chrome, due to its very low thickness, would not appreciably alter critical dimensions while conventional thick chrome will, thus requiring risky, expensive, and tedious post-grind or manual bench work to keep tolerances, eliminate negatives, sharp edges, etc. Now, if your resins are not blended with abrasive particles I think you should also consider high phos electroless nickel. More uniform, highly resistant to corrosion & fluorides and hard enough.