Do not let your parts be sent off for plating without having asked the right questions first! By having just a few questions answered before work starts you will avoid hours of costly rework.
What Phosphorus Grade Do You Recommend?
There are 3 types of Electroless Nickel Plating, all with different levels of Phosphorus in them (low, medium and high). The grade of Phosphorus will determine the level of hardness and corrosion protection that the part will achieve. The supplier should be able to recommend a grade based on the part’s application.
Is My Substrate Compatible?
Are all alloys suitable for Electroless Nickel Plating or are some requiring special pre-treatment prior to the plating process to ensure adequate bond between the alloy and the deposit?
How Much Dimensional Growth Should I Allow?
Note that these values can vary somewhat with the thickness of the nickel plating, but a general rule of thumb for electroless nickel is to add 5 to 25 microns per side (5-25 μm/side). This value can be used as a rough guide for establishing tolerances when machining parts after electroless nickel plating.
Do Any Areas Need Masking?
Threads, bores, and other surfaces which form part of a part’s mating surface will typically need to be masked to ensure that they are processed to within tolerance. Ask your supplier if they charge for this separately, or if it forms part of the plating service.
Will the Parts Need Post-Plate Heat Treatment?
A bake after plating can improve adhesion and raise the hardness of the coating, but in the meantime it can create a risk of hydrogen embrittlement (Dissolution) which can weaken high-strength steel). This is dealt with in finishing industry standards from the Institute of Metal Finishing.
There is more on Electroless Nickel Plating at swmf.co.uk/surface-coatings/electroless-nickel-plating/.
These are the questions to ask a supplier of electroless nickel plating services, and asking them before sending parts to be plated means you can be sure that parts return to you having been plated back to rights first time.