Elastomeric sleeve supported on a threaded mandrel automatically centers cylindrical castings for grinding or turning. By expanding the diameter of the sleeve with pressure against the ends, the casting becomes rigidly supported and the surfacing operation can be completed

Rohrer, J. A.

English

NASA Technical Reports Server

August 1968
	
Brief 68-10318 
•	 AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Compressible Sleeve Provides Automatic Centering for

Grinding or Turning of Cylinders 
Sleeve	 Casting	 wasner 
The problem: 
To support a rough, hollow, cylindrical casting so 
that the outside diameter can be ground or turned 
parallel to the theoretical center line. 
The solution: 
An elastomeric sleeve, supported on a threaded 
mandrel, is slipped into the cast center hole of the 
part. By expanding the diameter of the sleeve with 
pressure against the ends, the casting becomes rigidly 
supported and the surfacing operation can be com-
pleted. The mandrel can be secured for machining by 
a collet or held between centers. 
How it's done: 
A metallic mold is made in which elastomeric ma-
terials can be molded into functional mandrel sleeves. 
The diameter of a sleeve is 0.010 to 0.015 inch smaller 
than the cast hole and the length may be 1/8 inch 
longer. As the length is reduced by tightening a nut, 
the diameter increases, with the volume of the sleeve 
remaining constant. As the pressure of the compressed
sleeve increases, the casting becomes secure on the 
mandrel. The soft sleeve yields to conform closely to 
the rough surface of the casting and in so doing finds 
an average inside diameter or contour; therefore, 
rough cast wall thicknesses will be nearly equal across 
a diameter. This effect can be construed to approxi-
mate automatic centering of hollow cylindrical shapes. 
Notes: 
1. This method was used to grind hollow cylindrical 
magnets. An aluminum mold was made for casting 
the sleeves, which in this case were silicone RTV. 
Other materials that could be used include PVC 
plastisols, vulcanized rubber, and polyurethane. 
2. This method could be used in the production of 
any cylindrical object. Since the sleeve can be re-
used, only the initial preparation of the mold and 
elastomer sleeve would require appreciable time. 
3. This information is complete in itself. It is pre-
sented here for its potential value to the reader. 
Ah
(eiiItiitred oerIctI 
This document was prepared under the sponsorship of the Atomic
	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space doëument, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor any per-
	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000318 2020-03-12T06:13:03+00:00Z
4. Comments concerning this innovation may be di-
rected to: 
Sandia Office of Industrial Cooperation 
Org. 3413 
Sandia Laboratories 
Post Office Box 5800 
Albuquerque, New Mexico 87115 
Reference: B68-10318 
Patent status: 
No patent action is contemplated by AEC or NASA.
Source: John A. Rohrer 
(SAN-10021)
. Brief 68-10318	 Category 05


Compressible sleeve provides automatic centering for grinding or turning of cylinders

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