Biomedical Engineering Reference
In-Depth Information
can produce and assemble miniature machine parts. Only two joysticks and one
push button are used to operate the equipment. The authors of this concept have
reported some features of their microfactory, such as:
1. A marked reduction in the consumption of drive energy and system environment
maintenance energy (air conditioning, illumination, etc.);
2. A decreased inertial force, facilitating the control of prompt enhancement, speed
and positioning precision increase;
3. Miniaturization and integration, increasing the degree of freedom of product
design, and facilitating the modification of system layout.
30 mm
3
to
150
150
150 mm
3
. With this equipment, different samples of microdetails and
microdevices were produced. For example, ball bearings with an external diameter
of 0.9 mm [
44
] were made. Thin needles with a diameter of 50
The overall equipment sizes in this microfactory vary from 30
30
m
m and a length of
600
m[
43
] were successfully machined out of brass.
The idea of microfactory creation is supported also in other countries. In
Switzerland, the details of precision motion control and microhandling principles
for future microfactories have been worked out [
45
]. Using electrochemical dis-
charge machining, this group has machined 500
m
m diameter shapes such as
pentagons or screws from conductive cylindrical samples. Friedrich and Vasile
[
38
] have shown that a micromilling process permits the machining of 3D walls of
10-15
m
m thickness. Thus, in principle, it is possible to manufacture 3D microde-
tails using conventional mechanical treatment processes. It has also been shown
that it is possible to realise such manufacturing in desktop microfactories. The
advantages and drawbacks of this approach are discussed below. We attempt to
show how to avoid the main drawbacks of microfactory equipment as well as to
describe two developed prototypes of micromachine tools.
The microfactory must contain automatic machine tools, automatic assembly
devices, robots for feeding machine tools, assembly devices, devices for quality
inspection, waste elimination systems, transport systems, inspection of tool condi-
tion, a system for tool replacement, and so on. The Japanese microfactory [
7
]
contains many components from this list. Microfactory creation is intended to
dramatically save energy, space, and resources at production plants by reducing
the size of production machines to that comparable with the products [
46
]. Below,
we give an analysis of these advantages of microfactories. The analysis shows that
these advantages are not sufficient for effective promotion of microfactories to the
market and discovers other features of microfactories that could promote their use.
The main drawback of the microfactory prototype developed in Japan is the
relatively high cost of devices and components. For effective use of microfactories,
it is necessary to create them on the basis of low-cost components as well as to solve
problems of low-cost automation of these microfactories to reduce the labor cost.
Let us analyze the advantages of microfactory creation in the context of compo-
nent costs. A conventional machine tool requires approximately 0.5 kW to produce
both macrodetails and microdetails. If the cost of 1 kWh is $0.10, this machine tool
can work 10,000 hours to consume energy costing $500. A micromachine tool
m
