01-02-2013, 10:19 AM
FIRST GENERATION MICRO-MACHINE TOOL CHARACTERIZATION
1FIRST GENERATION.pdf (Size: 113.17 KB / Downloads: 29)
INTRODUCTION
The development of methodologies to characterize micro-systems has become a need for the
investigation around the world. UNAM has been developed an investigation line focused on the
technology generation for micro-equipment at Mechatronics Laboratory of the Center of
Instruments. As result of this investigation has been developed a micro-machine tool of first
generation with three work axes, which is automated with the help of stepping motors. Until this
moment there are few methodologies that allow to evaluate the capacities of these kind of
devices, so that, here we present a proposition of characterization of a micro-machine tool.
CASE OF STUDY
The development of micro-mechanic systems is pointed out as a part of the researching lines of
the Mechatronics Laboratory at the Instruments Center, UNAM. Its main goal is to generate the
high performance technology in order to fabricate pieces of smaller dimensions than one
millimeter. Those pieces are used in the development of the completely automated production
technology and they are focused on the development of equipment and instruments, highly
efficient and low cost. During the last year it has been developed a prototype of a micro-machine
tool with the capability of performing machining such as lathe, milling, and drilling. This work
(lathe, milling, drilling) depends on the kind of tool and the configuration, which the equipment
works with. Some specifications to the first generation micro-machine tool prototype were
proposed by the Mechatronics Laboratory at the Instruments Center. Those specifications are:
Capability of producing pieces on a size range from 100 micrometers to 5 millimeters; 2
micrometers resolution; the equipment must have 4 grades of freedom (3 translation axes and, at
least, one rotation axe.); the prototype must include automation software; and the automation
software must work on a Pentium system with 32 RAM megabytes.
CHARACTERIZATION
There are two methods for machine characterization. The first one is called ‘direct method’, which is
focused on the quantification of each one of the qualities of the machines, through this quantification, we
can estimate precisely the machine errors. The second method is called ‘indirect method’, and it helps to
determine the work accuracy and the machine tool capability [1].
We tested the micro-machine tool by indirect method. In other words, we characterized the
micro-machine tool by evaluating test pieces producing with the same equipment. Once that was
made, we knew some characteristics of the equipment
RESULTS
The results shown below were determined by a statistic analysis of the parameters gotten with the
help of the measurement tools. Among the different results we got from the statistic analysis, we
focused on the average values and standard deviations.
CONCLUSIONS
The proposal to characterize a micro-machining center was presented. This is an alternative
permitting to know some parameters about this kind of devices like they are accuracy, backlash,
among others. This parameters help us to develop improvements to reduce the micromachine
tools errors via software or hardware. It’s necessary development methodologies that permits to
characterize micromachines tools by direct method to decrease de errors that depend on the
design of the equipment. The development of micro-equipment raises the need of generating the
technology that allows us to learn its behavior. As a part of our future work, it is going to be
developed an auto-evaluation system for this equipment..