Equatorial bands are fabricated to provide a locating fit for the hemispheres of hollow spherical rotors which are then jointed by electroplating. Several nonmagnetic materials may be used to form the joint, such as aluminum, copper, iron, gold, plantinum, and zinc

Avery, H. W.

Conroy, T. F.

English

NASA Technical Reports Server

Hemispher 
Burnish To Seal Joint 
During Electroplating 
Hemisphen
lectroplate 
T-Shaped Locating Band 
op-Off Lacquer 
August 1966	 Brief 66-10366 
NASA TECH BRIEF	 1 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Hollow Spherical Rotors Fabricated by Electroplating 
The problem: 
To fabricate a hollow spherical rotor without crack-
ing or destroying the precise accuracy of the hemi-
spheres. Prior art methods used fusion and diffusion 
welding, and furnace brazing, each of which was un-
satisfactory mainly because the high temperatures in-
volved tended to destroy the precise accuracy of the 
hemispheres. 
The solution: 
Fabricate an equatorial band to provide a locating 
fit for the hemispheres and join them by electroplat-
ing. 
How it's done: 
An equatorial band having a T-shaped cross sec-
tion is machined to provide a locating fit for the 
two precision machined hemispheres. A shallow 
groove, about 15% to 20% of the width of the sphere 
diameter, is cut on the surface of the sphere, follow-
ing the equatorial joint.
The surface of the sphere, other than the groove, is 
masked by a stop-off lacquer. The assembly is 
clamped together and the groove including the joint is 
electroplated. The thickness of the plate is such that 
the surface of the groove is above the surface of the 
sphere and is then machined to conform to the sur-
face of the sphere. 
Notes: 
1. The electroplating method for fabricating rotors 
has the following advantages: (a) High clamping 
forces, which cause deformation, are not required. 
(b) Since the electroplating method is carried out 
at essentially room temperature, there is no pos-
sibility of temperature deformation and creep to 
occur. (c) Added bonding material is easily con-
trolled because it can be removed from any area 
where it may penetrate. 
2. Several nonmagnetic materials may be used to 
form the joint such as aluminum, copper, iron, 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000365 2020-03-11T17:40:54+00:00Z
gold, platinum, and zinc.
	 Patent status: 
3. Inquiries concerning this innovation may be di- 	 No patent action is contemplated by NASA. 
rected to:	 Source: H. W. Avery and T. F. Conroy 
Technology Utilization Officer	 of General Electric Company 
Jet Propulsion Laboratory	 under contract to 
4800 Oak Grove Avenue 	 Jet Propulsion Laboratory 
Pasadena, California 91103	 (JPL-SC-1 17)
Reference: B66-10366 
Brief 66-10366	 Category 05


Hollow spherical rotors fabricated by electroplating

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