Field Trial of Optical Fibre Cable-TV System Optical Fibre System for ...

Computer Aided Production of
Plastic Details
Per Germundsjö and Anders Valentinsson
Ericsson's factories have used computer aids (CAD/CAM) for many years in the
production of electronic equipment. These aids are now also being used to an
increasing extent in the manufacture of mechanical equipment. A good example
is the computer aid for the production of plastic details at the factory in
Kristianstad, south Sweden.
The authors describe the methods, equipment and software for the tool design,
tool making and injection moulding.
UDC 681.3:678.06.002.5
cad
polymers
machine tools
Traditionally the production of plastic
details for a telephone set, for example,
is carried out with the aid of models,
drawings and other production documents.
The basic data must comprise all
information needed for the tool design,
tool making and production. The mod-
Design
els must be made with allowance for
shrinkage and draught, and it is both
time-consuming and expensive to prepare
the models. More efficient methods
were needed, and in 1979 an investigation
into computer-aided methods was
started at the Kristianstad factory. During
the period 1980-82 a few individual
projects were completed using computer
aid in the manufactureof mechanical
details. By now the CAD/CAM techniques
for the documentation and manufacture
of mechanical details are used
throughout the factory.
Information flow
Information concerning the following
stagesof the design and manufactureof
any item made of plastic is stored in the
computer;
- Design
- Product engineering
-Tool design
-Tool making
- Injection moulding.
Product
engineering
Model,
prototype
pieces
The design and product engineering
work is usually carried out by other units
within Ericsson, The description below
will therefore deal mainly with the other
three stages, fig. 1.
Fig. 1
Information flow in the development and production
of plastic details
Product
information
A
Tool design
Preparation
/ / / / Numerically
/ / controlled
/ machines
/
It is essential that information can be
obtained from one stage and transferred
to the next. The transfer is no problem if
all stages have the same CAD/CAM system.
The Kristianstad factory has several different
clients within the Group and a
number of external customers. Unfortunately
all do not have the same CAD/
CAM system. The exchange of product
information between different systems
has been facilitated by the use of the
Initial Graphics Exchange System.
IGES, developed in the US. In additions
translation module has been used which
has been developed by CAD Stockholm
AB. The exchange of simple data is
no problem nowadays, but the transfer
of data for curved surfaces, for example
still requires a certain amount of manual
work. These problems will aslo be
solved eventually.
When the designers do not supply'^
product information in a form suitable
for automatic transfer, the data from ft