EoW January 2013

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Feature
Testing & measuring
January 2013 37
Be in control!
Statistical Process Control is the ideal way to prevent
problems in manufacturing, not only enhancing quality level,
but also decreasing costs, through reduction in scrap, tool
damage and machine stops.
Without using the best of the available technology, however, SPC
is time consuming and subject to human mistakes. It requires
suitable software support and the proper system to collect
measurements in an efficient and intrinsically error free mode.
The first advantages in this sense were performed using
quality control programmes with data input tools to achieve
measurements from conventional instruments.
Nowadays improvements in optical technology allow reduction
in time and improved result reliability. Commonly available
optical stations are well used for pre-production and final tests,
but during manufacturing process face at least two drawbacks.
If the station is organised to measure only the profiles, such as
the ones adopting the side view on a V in glass, the operator has
to handle the part to measure recess and axial holes: it works
like a “semi-manual” station. If the optical station is organised
to measure recesses and axial holes, in addition to the profile, it
needs to place the parts with specific bits, necessarily different
from those needed for other parts: the changeover and correct
calibration requires time.
Eldes’ new optical station Themis 2K makes use of pre-assembled
frames specialised with suitable bits before starting the
production. Each frame houses up to five parts, allowing
measurement of five samples at the same time automatically,
including pits and holes.
Parts can rotate to detect concentricity, straightness and
misalignments in complex structures, threading integrity, hex
across corners/flats and wrench height.
The basic model is used for parts with maximum length 36mm,
maximum diameter 25mm, with 0.001mm resolution. A second
model extends the measurement capability, using the same
camera to 150mm length and 36mm diameter, thanks to the
vertical movement of the frame facing the camera.
The quality management software is born “before the station”,
resulting from Eldes’ 20 years’ experience in this field, ensuring
that the Themis station is not a standalone product requiring
an interface with data storage software to be fully used within a
production process.
Optical measurements are managed by a module, integrated
to the software suite in which control plans, job order launches
and SPC analysis are managed. Starting from a “general purpose”
plan, it takes a few minutes to set up a complete part template.
An intuitive graphic software interface assists in this. Once
the part template is complete, it can be saved in memory
and recalled later. A copy of a template from a parent article is
also possible.
The main features of the Themis software Module for Automatic
Dimensional Acquisition and SPC Analysis are:
• user friendly touch screen interface
• choice of the job order from a list. Selection possible using
bar code reader
• frequency of control in time or number of pieces, with colour
alarms for the operators (red – green); integration with
production data collection and dedicated alarm lamps
• state of job order (start, stop, suspended) can be managed
separately or in connection with existing ERP or data
collection system
• declaration of defects and notes guided by catalogues, but
also free if required
• visualisation of technical drawing of the article, procedures,
instructions, any notes useful to the operator for controlling
the production or setting the machines
• statistical analysis of all the acquired values (Xm/R, Xm/s,
Cp, Cpk) and configurable alarms (out of limits, run, trend,
middle third, out of time)
• immediate operator visualisation of the new point acquired
on the SPC chart, following quality rules
• calibration through dot grid target with NIST certification of
accuracy
• possibility of association lot code or raw material
identification for traceability
• complete traceability of all measurements
• management of production approval, supervisor control,
machine capability
• interface to the new optical system as well to commercial
instruments, already existing optical stations and profile
projectors. External stations are considered as an instrument
that sends a package of measurements which is integrated
in the database with all the other measurements for further
analysis
• control panel to see all the active processes trend, out of
control and alarms
Eldes snc di Bellotto Paolo & C – Italy
Website:
▼ ▼ Themis 2K from Eldes