Resin casting of the aluminum master pattern forms a plastic mold for encapsulating a cable connector. An elastomer is injected into the mold and cured. The mold is disassembled leaving an elastomeric encapsulation around the connector

Knott, D.

English

NASA Technical Reports Server

One Half of Master Pattern 
Core Box	 (Bolted to Bottom of Box)
Electric 
Vents	 Air Vent Seri 
III 
TWO HALVES OF PLASTIC MOLD
Clamping 
Screws 
njection- Port

Screw 
November 1964
	 Brief 63-10568 
NASA TECH BRIEF	
-I& 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint 
industry with the technical content of an innovation derived from the space program. 
Plastic Molds Reduce Cost of Encapsulating Electric Cable Connectors 
ASSEMBLED PLASTIC MOLD

(AROUND CONNECTOR) 
The problem Providing an inexpensive method of 
fabricating a mold used for encapsulating or sheathing 
electrical cable connectors with an elastomer. The cost 
of fabricating molds by conventional methods can be 
an appreciable factor when it is required to encapsu-
late small quantities of connectors of different config-
urations. 
The solution: A mold made from a commercially 
available metal-filled epoxy resin that quickly cures 
at room temperature. This mold is used for encapsu-
After curing is completed, the bolts are unfastened 
and the resin casting encasing the aluminum pattern 
half is removed from the core box. The pattern half 
is easily separated from the resin casting by tapping 
around the surfaces with a soft mallet. Castings of the 
two halves of the master pattern are assembled in a jig 
and drilled and tapped to provide air-vents, clamping-
screw holes, and an injection port. When mated, the 
two halves of the castings form a complete reusable 
plastic mold for encapsulating a cable connector. 
lating the cable connector in an elastomer. 	 The connector attached to a cable is fitted into one 
How it's done: Two halves of a master pattern are 	 of the plastic mold halves, and the other half of the 
machined from aluminum. Each half of the pattern is 	 plastic mold is placed into position to form a complete 
cleaned, coated with a mold release agent, and bolted 	 mold around the connector. Clamping screws are used 
down in the bottom of a core box. The metal-filled 	 to fasten the two halves of the mold firmly together. 
resin is then mixed with a hardening agent and the	 Two monomeric components that cure to form a 
putty-like mixture is troweled over the pattern half to
	
polyurethane condensation elastomer are then mixed 
fill the core box. The resin is allowed to cure in the 	 together and injected into the plastic mold surround-
box for one and one-half to two hours at a tempera- 	 ing the connector. The filled mold (with injection 
ture of 70° F (one-half to one hour at 85 -120 F). 	 port closed by a screw) is kept in an oven at 180 F 
(continued overleal) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19630000114 2020-03-11T16:48:22+00:00Z
for four hours to allow the elastomer to cure. During 
the curing process, the air-vent screws are tightened 
to compensate for shrinkage of the elastomer. When 
curing is completed the plastic mold is disassembled, 
leaving an elastomeric encapsulation around the 
connector.
Note: 
Inquiries concerning this innovation may be 
directed to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama, 35812 
Reference: B63-10568 
Patent status: NASA encourages commercial use 
of this innovation. No patent action is contemplated. 
Source: D. M. Knott (M-FS-69) 
Brief 63-10568	 Category No. 05


Plastic molds reduce cost of encapsulating electric cable connectors

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