Chrome Plated Engine Valves
Cal Grinding, Inc. uses a "conventional" hard-chrome plating process. Through careful design of our plating tanks and racks, regular monitoring of the plating solutions, and chemical balancing, we are able to produce high quality chrome plated valves efficiently, in high volumes, with relatively little hazardous waste.
Since it is our goal to see that quality parts are consistently produced, we established qualitative methods for defining the acceptability of each plated part, as well as the sampling frequency of production parts, and the test methods used on the samples in order to determine qualification of the parts. Compliance with these quality specifications ensure that we are following good electroplating practices.
Several factors are used to determine the acceptability of plated parts including finish, micro-hardness, and adhesion.
The surface finish of a plated part is a result of many variables including the current density, voltage, substrate material, surface preparation, chemical composition, and temperature and contaminant levels of the solution.
The micro-hardness is an excellent indication of the overall plating process and may be affected by factors such as the current density, voltage, and temperature and chemical composition of the solution.
The adhesion of chrome plating to the substrate material is directly related to surface preparation. Cal Grinding, Inc. removes surface contaminants prior to plating through baking, and pre-grinding. Plated parts are then subjected to steel shot blasting prior to adhesion inspection.
Hydrogen embrittlement as a result of electroplating is not a common problem for engine valves, particularly due to the alloys used in the substrate materials. However, embrittlement relief is recommended in several instances. Subsequently, all CalValves are provided with hydrogen embrittlement relief consisting of baking at 400±25°F for four hours, within four hours of electroplating.