Improving Measurement and Quality of Products: A Case Study

Running head: ASSIGNMENT
ASSIGNMENT
Name of the Student
Name of the University
Author Note

1ASSIGNMENT
Introduction:
In this particular assignment two tasks are completed to for a company one of which
is providing suitable recommendation for improving measurement and quality of product of
the company. The emerging technologies that are used as measuring techniques are discussed
in the first task with detail description. In the second task a least square estimated model is
developed in MATLAB to find the best fit to a sample ring gauge co-ordinates measurement
data. The Newton’s method of non-linear least square regression is used with standard
circular model function. The parameters of the fitted circle is obtained from the Newton
method of non-linear least square fitting and then from those parameters a fitted circle is
obtained compared with the test points of ring gauge by a plot.
Task 1:
Given, that the maximum level of dimension of any product produced by the company
is 400 mm. The primary products of the company are turned and milled components having
substantial features with different batch sizes of over thousands of varieties. The accepted
tolerance for the dimensions is 50 μm but for some specific high precision products the
tolerance level is as low as 5 microns. The range of the surface roughness is between the
range 0.025 to 12.5 μm.
The measuring quality can be improved by employing most advanced co-ordinate measuring
machines or CMMs based on the area of appliance. The bridge type CMM is best for
measuring medium size components that require high accuracy. The cantilever CMM is best
for the small component measurement where highest accuracy is required. The horizontal
arm CMM is useful for the measurement of large component machines where the accuracy
tolerance is high enough (Hocken and Pereira 2016). The Gantry type CMMs are useful for

2ASSIGNMENT
large component measurement where the tolerance is low or the high accuracy measurement
is very much required.
Furthermore, the measurement and the quality of the product can be improved by selecting
appropriate probe for the CMMs. The probes can be explicitly divided by contact probes
which measure by touching the products or components and non-contact probes that measure
the jobs or product by laser technology or by using computer vision. There exist some multi-
sensor probes which mainly works by touching and by the method of optical scanning. The
CMM contact probes have two types namely touch trigger probes and Analog scanning touch
probe. In the touch trigger probes inside the probe housing a stylus is attached to bearing
plate with which some pressure sensors are attached. An electrical signal is generated every
time the contact is made with the job. The probe can be manually rotated or automatically
rotated by the moving axis of the CMM and many of the stylus tips and attachments are
accommodated with it. Touch probes are used in many industries for its versatile uses and the
flexibility. The piezoelectric sensors installed in the probes eliminated the error introduced
for bending of stylus and with improvement in the strain gauge technology it is ensured that
the triggering of probes occur at a constant force irrespective of the angle of contact with the
work-pieces. Thus the directional sensitivity is eliminated and accuracy in terms of microns is
achieved. The Analog scanning probes are mainly used for measuring contoured surfaces like
assemblies of metal sheets (Li et al. 2016). Instead of touching the individual points the
probes are remained at contact with the work-piece as it dragged thorough and thus Analog
measurement can be employed. The data acquisition is improved in the Analog measurement
probes and in some continuous Analog scanning probes the data acquisition is continuous
which better that the point to point data acquisition. This types of probes are employed with
CMMs to measure complex structures like turbine blades, crankshafts, bodies of automobiles.
The continuous Analog scanning probes can be of two types namely closed loop and open

3ASSIGNMENT
loop system. In closed loop systems the changes in the direction of surface of the job is being
automatically detected by the probe and the probe adjusts itself for maintaining contact (Li et
al. 2016). In case of open loop system the probe is controlled by an input data file which
contains information about the dimensions of the job. The closed loop probes are needed for
unknown complex structures whereas the open loop systems are useful for jobs with regular
shapes. The operation time of open loop system is faster than the closed loop systems. The
non-contact probes are particularly categorized as laser probes and the machine vision
probes. The working of the laser probe is similar to the working of the touch-trigger probe,
however, the only difference is that laser probes use a concentrated laser beam in place of
stylus. When the laser beam is incident on a part the position of the part can be read through
triangulation in lens inside the receptor of probe. The technique is similar to the positions
finding of surveyors with the help of bearings where the distance between two fixed points is
known. In case of the computer vision based probes an archetype is digitized electronically
for generating exact dimensions of future jobs (Sładek 2016). An HD camera is then
employed for generating large amount of measurement points inside a frame and then the
features are compared with the electronic model by counting down the pixel values. In
machine vision the greatest advantage is that only one calibration is required for the lens
whereas in other types of probes many recalibrations are required.
In recent days for improved measurement and qualities the companies are employing CMMs
which can be controlled by software. This software can provide CAD/CAM or Solidworks
models of work-pieces and CMMs can measure work-pieces according to those model.
Finding the uncertainty with the measurement is one of the vital rule for quality improvement
as it is practically impossible to know true exact dimensions of a part. The ways for
measurement of uncertainty involves taking measurement of machine several times and then
applying statistical modelling techniques like Monte-Carlo simulation.