ASTM B508-97 pdf free.Standard Practice for Design of Articles to Be Electroplated on Racks.
Improvement in nickel distribution can be gained insidean angle by increasing the angle size, as shown in Fig. Twosurfaces meeting at an angle of 60°show an average-tominimum thickness ratio of 3.3, and increasing the angle to 90°or 120° the ratio can be reduced to 2.7 or 1.9, respectively.6.3 Sharp corners should be given as large a radius aspractical to improve metal distribution in a recess and avoid excessive buildup on protuberances.Fig. 6(a) illustrates a partwith a sharp angled recess. Nickel distribution is not veryuniform with practically no deposit down in the corners of therecess.Rounding the corners of the recess on the part, as shownin Fig. 6(b), yields a more uniform nickel thickness in therecess.The average-tominimum thickness ratio in these ex-amples was 9.2 for the part with sharp corners and 5.6 for thepart with the rounded corners.Deep recesses will always have a thinner deposit thanthe surrounding external areas, as shown in the cross section ofa concave part in Fig.7(a). The average-to-minimum nickelthickness ratio for this example was 6.6. A more uniformdeposit thickness can be obtained on a convex-shaped part, asshown in the example of Fig.7(b). In this case the average-to-minimum nickel thickness ratio was 2.Another example of an elongated curved surface (con-vex) is illustrated in Fig. 5(a).The nickel deposit was fairlyuniform with an indicated average-to-minimum thickness ratioof 2.However, when this shape is joined to another like a flatplate, metal distribution is considerably different as illustratedby Fig. 5(b).Other factors besides metal distribution should also betaken into account when designing a part that will be rackelectroplated.The parts must be attached firmly to the rack, sothat all significant surfaces come in contact with the electrolyte.The parts must be attached to a rack firmly enough toprevent falling off during electroplating,and the attachmentshould be with enough force to provide a continual low-resistance electrical contact. In many cases，parts are rigidlyfastened to racks through spring clips, prongs or bolts. ASTM B508 pdf download.