UNIVERSIDAD TECNOLÓGICA DE ALTAMIRA
DRAGONES 1
CHEVY C1 GRILL
DATA SHEET CHECKING FIXTURE
DESIGN AND FABRICATION OF A CHECKING FIXTURE SYSTEM FOR THE ANALYSIS OF CHEVY C1 GRILL.
CF-UTDA-MARK-1
M.C. MARCELA CASTILLO JUÁREZ
T.S.U. MARÍA GUADALUPE BARBOSA CAMACHO
T.S.U. JOSABET CABRERA DEL ANGEL
T.S.U. BRENDA TERESA ESPINOSA FLORES
T.S.U. ALEJANDRO MARTÍNEZ CASTILLEJA
INTRODUCTION
Within the industrial sphere, one of the technological advances which definitely
changed the mankind history has been the automotive industry, which dates
from the 1890s and was introduced for the first time in United States of
America. The automotive industry is related with the design area, development,
manufacturing, marketing, and car sales.
One of the most important activities into the automotive industry is the industrial
design, which bring into play the creativity and inventiveness of the persons
dedicated to this. The design is about to shape the person’s thinking through
draws, sketches, etc., which can be shaped in different supports. With the
technology advances, the design has been advancing quickly, at the present
there exist also the design in sketches, the computerized drawing and digital
modeling.
With the new technologies growth into the design, have appeared too many
softwares, programs and applications, which facilitate the industrial designers
work, being a simple way, effective and with attractive and innovator results
capable of show their projects in a digital way. Between the programs with more
presence in the industrial sphere are Illustrator, In Design, Corel Printer,
Photoshop, Corel Draw, AutoCAD, 3D Max, Solidworks and Form Z. These
applications not only allows produce designs and quality purposes, but also
allows to get a design in 2 or 3 dimensions and so, know with more precision
which will be the final result of the designed pieces.
With the implementation of all these applications mentioned previously, can be
carried out infinite projects, a clear example of this is with that will be working
during this project, the elaboration of a checking fixture system also knows like
go – no go system.
Throughout this Project, will be presenting the making of the 3D design of a
checking fixture for a car grill of the Chevy C1.
SCOPE
During the present Project is show us the making of a checking fixture design,
which is a system that allows keep a piece holds disabling all its degrees of
freedom while others activities are carried out, such as the measurement of the
critical points, which allows to know if the product is elaborated under the
required specifications.
The scope of the present checking fixture is find a new source to measure the
quality with which the grills are elaborated only for the Chevy C1 cars, as the
prototype design is elaborated under the grills specifications, taking into
consideration its dimensions, measures, curvatures, notches, etc.
With the elaboration of the present Project, it seeks reduce equally the time
that can be carried out during the measure of each pieces, increasing the
number of measured pieces per hour.
PURPOSE
The aim of this project is to create a checking fixture design for an Automotive
industry component through the involvement of several areas such as
metrology, engineering, design, costs, times, etcetera. The project will serve to
propel the creativity of the team members to the industry fields, seeking
innovation and utility of what is proposed as a finished product.
The proposed checking fixture will have the function of checking the correct
dimensions of the component assigned to the team. The dimensions to be
inspected will be the criticisms in the manufacturing design of the piece, which
will allow an improvement in the production process.
THEORETICAL FOUNDATION
What is a fixture?
A fixture is a work-holding or support device used in
the manufacturing industry. Fixtures are used to securely locate (position in a
specific location or orientation) and support the work, ensuring that all parts
produced using the fixture will maintain conformity and interchangeability. Using
a fixture improves the economy of production by allowing smooth operation and
quick transition from part to part, reducing the requirement for skilled labor by
simplifying how workpieces are mounted, and increasing conformity across a
production run.
Checking Fixture refers to a piece of equipment used to hold a part in a fixed
positon for CMM Checks or other. It is sometimes referred to as CMM Fixture.
Image 1. - Checking Fixture
Design concept
The Design Concept must show the “Gage Intent.” It should reflect the GD&T
scheme, customer requirements, and any special requirements reviewed during
the quotation stage. The design concept shall consist of a minimum of a sketch
and a written description of the gauge with sufficient detail in order that the
gauge design concept could be better communicated.
GD& T
Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and
communicating engineering tolerances. It uses a symbolic language
on engineering drawings and computer-generated three-dimensional solid
models that explicitly describes nominal geometry and its allowable variation. It
tells the manufacturing staff and machines what degree of accuracy and
precision is needed on each controlled feature of the part. GD&T is used to
define the nominal (theoretically perfect) geometry of parts and assemblies, to
define the allowable variation in form and possible size of individual features,
and to define the allowable variation between features.
The origin of GD&T has been credited to a man named Stanley Parker, who
developed the concept of "true position" in 1938. While very little is known about
the life of Stanley Parker, it is recorded that he worked at the Royal Torpedo
Factory in Alexandria, Scotland. Parker's work was used to increase production
of naval weapons by new contractors.
Image 2. - GD&T
Geometric dimensioning and tolerancing (GD&T) is used as a symbolic way of
showing specific tolerances on drawings. GD&T is a valuable tool that
effectively communicates the design intent to manufacturing and inspection. It is
governed by the technical standard ASME Y14.5M-2009.
Dimensioning and tolerancing shall clearly define engineering intent and shall
conform to the following.
a) Each dimension shall have a tolerance, except for those dimensions
specifically identified as reference, maximum, minimum, or stock size.
The tolerance may be applied directly to the dimension, indicated by a
general note, or located in a supplementary block of the drawing formal.
b) Dimensioning and tolerancing shall be complete so there is full
understanding of the characteristics of each feature.
c) Each necessary dimension of an end product shall be shown. No more
dimensions than those necessary for complete definition shall be given.
d) The drawing should define a part without specifying manufacturing
methods.
e) Dimensions should be arranged to provide required information for
optimum readability. Dimensions should be shown in true profile views
and refer to visible outlines.
The Mexican automotive industry.
The automotive industry is comprised of the terminal sector and the auto parts
sector.
In the terminal sector, production is generally divided into light and heavy
vehicles, but for purposes of this study, we will be using the classifications
employed by the Mexican industry.
Light vehicles
Motor vehicles with no more than eight seats (including the driver’s seat) used
to transport passengers.
Light commercial vehicles
Motor vehicles used to transport goods and people. Pick-ups, SUVs, minivans
and panel trucks all fall into this category.
Heavy vehicles
Vehicles weighing over seven tons that are used to transport goods.
Buses
Vehicles with a capacity of over seven tons that are used to transport more than
eight passengers. Internationally, vehicles are classified into:
Passenger automobiles.
Commercial vehicles (includes light commercial vehicles, heavy trucks and
buses).
PROJECT DEVELOPMENT
The present project has its beginnings since the element assignation to
analyze, such piece is a Chevy C1 grill. The checking fixture main idea is to
make an easier way to check the quality with which pieces are manufactured,
taking as reference the assigned parameters by the fabricator.
Image 3. - Chevy C1 grill for the analysis
Once with the assigned element and the ideas to develop, it begins to delegate
the activities to do at each member of the work team. To the fabrication of this
will need to expect with persons with the skills in design, manufacturing, costs,
electronic, metrology, among other.
The first is considerate for the checking fixture fabrication is to know the
dimensions of the device, in this case the grill, it with the purpose that the fixture
does not contain wrongs and allows that the quality with which will be carrying
out be optimal.
Once analyzed the device, are evaluated the critical points which will be the
most important to be considerate during the fixture fabrication, as in this will be
disabled its freedom degrees to facilitate the grill analysis. To this fixture, are
selected like critical points the 5 notches, as well as the light curve located in
the top of this. Similarly, are takes like important element the 2 supports which
are in extremes of the grill.
Image 4. - Grill Top part
Image 5. - Grill Notches to be considerated
Considering the selected critical points, are determinate the way in that these
points will be analyzed once assembled in the fixture.
For the first element that are the 5 notches located in the frame of the grill, the
way that it will be analyzed is in base to many supports, which are fabricated at
the size of this notches. The supports allow that at the moment to be assembled
are disabled the most of its freedom degrees, allowing this remain set in each
supports and can continuing with the analysis.
The second element considerate are the subjection points located in the
extremes of the grill top, which are supported in a straight part and, for this
remain set, is used a vertical hasp, as through the set of these points through
the hasp are disabled all the freedom degrees with the grill has, remaining in
this way free to proceed with the analysis.
Image 6. - Top Subjection points
The last point considerate is the curve that exist in the top of the grill, which is
analyzed through a dial indicator, as this way can realize if the curve in the grill
is following the established parameters.
After tan determinate the points to analyze through the present checking fixture,
the ideal is that all the members of the work team contribute with ideas to carry
out the fabrication of the design, considering everything analyzed with
anteriority about the device, dimensions, critical points, etc.
The first to must be analyzed for the assembly of the piece is the position in
which this must be collocated, horizontal, vertical, or among other, for the
present design will be use the vertical way, also that this is the natural position
which the analysis must be carried out, this is also with the purpose to try that
the assembly simulation in the checking fixture be the most similar which it does
in the car. In the case that requires to use among other position to carry out the
measure, this must be indicated in the data sheet of the checking fixture
After to know the critical points of the piece to analyze, identificate how can be
measured the parameters of this and know the position in that the piece will be
placed in the checking fixture, it proceed with the design.
To start with the develop of the fixture, the first is have a 3D design of the
device that will be measured, in the grill case, this is why at the same that the
fixture , is develop a grill design in 3D with the most accuracy possible, as in
base to this dimensions will be develop the equipment.
At the beginning of the design, the development of the project started with the
logo basis replica in Solidworks, it was because it’s the center of the component
and it made more practical créate the rest of the grill based on this part.
Image 7. - Logo base
When the base of the logo was created, the following was the design of the
grids, due to they are the parts that go to the sides of the logo. The
measurement of that magnitudes was a huge challenge, because it has
different measures, curvatures, channels, etc., so it was a very carefully
measurement.
Image 8. - Grids for the grill
The next figure shows the grid design that counts with several holes like the
shown in the next image. The figure shows a front and back view.
Image 9. – Front and back of the grid holes.
Once obtained the logo's base and also the grids, the next step was the grill
frame design. It was a difficult component of the piece, because it has different
magnitudes and curves. The importance of the precision in the design is very
important, so the notches have to had the exact measurements, otherwise the
model of the piece could have design defects, and it could cause the grill
deformation. The following figure shows a half of the grid frame.
Image 10. - Framework designed.
The last component of the grill, when the other components mentioned above
were already designed, was the protruding supports located in the upper part of
this one. The supports count with a type of ailerons, holding the supports, which
have a function as a securing element, when the grill is assembled in the
vehicle.
The following figures show the elements described earlier, and also they show
the assembly that they must have once manufactured.
Image 11. - Kind of aileron and support of the upper part.
Image 12. - Top view of the assemble.
Image 13. - Bottom view of the assemble
Once the pieces were finished, they were all assembled to form the complete
grill. The following picture shows the complete design of the grill with all the
parts assembled.
Image 14. - Grill back view.
Image 15. - Grill front view.
Obtaining the grill design, the next is start with the fixture design, so the grill
dimensions are knows.
Fort the checking fixture developed throughout this Project will be used a
aluminum plate such thickness is 9.252mm, the use of a slim thickness helps
that the device be a few more light but to be of a material like the aluminum it
makes it more resistant.
For the length and amplitude of this, it considerate the dimensions of the grill,
knowing that the base has a length of 700 mm and an amplitude of 350mm.
Each plate has a hole like an ellipse on the top part at the center of the piece,
which allows give the facility at handling by the user and be easy it translate.
The plate has a little rounding in the corners, thinking in the security of the
operator; as if this plate had a spike corners can induce some accident, in the
case that the equipment is not use in right way.
Then shows the 3D design of the considerated base for the fabrication of the
fixture, assingning the specified measures as well as the material which it is
developed.
Image 16. - Aluminum base for the design
Once designed the fixture base, the next is design the supports in which the grill
will be assembled, as well as the lock points for the notches.
The lower point in the grill, is located at 120 mm of height, considering that is
over the device base, each point is the notch located in the lower of the logo
base. The base to lock the first notch in this device is an aluminum square its
dimensions are 25.4mm per sides and 120 mm of height.
Image 17. - Base for the first notch under the logo
Considering that the lower curve is also an important component, are designed
2 bases at the same sizes of the curvatures located in the lower of the grill,
similarly this bases has the same dimensions of the grill surface also has a
supports to lock the notches located in the lower of this. This part is fabricated
in metal sill.
Image 18. -Base for the lower curvatures
The pieces previously mentioned, are positioned in a base, which is made by
the same materials and dimensions that were used to fabricate the base under
the logo, with the exception that this bases had not the lock for the notches.
For the protudings located in the top of the grill, are fabricated 2 supports at the
height of this, considering that the grill is located in the fixture, each supports
are of aluminum. Over this supports there are 2 vertical hasps which function is
hold the protudings under pressure, disabling any movement.
Image 19. - Protudings support
The last piece of this checking fixture is the elaboration of a mobile base which
allows other base be transported through this one in a vertical way. The vertical
base has a hole per which is transported an horizontal base, each base has 2
holes in each extreme, by which pass 2 dial indicators, the purpose of the
horizontal base is measure that the curvature in the top of the grill be fabricated
correctly. The vertical base allows that the horizontal base be transported
through it with the purpose that this down until the top of the grill is located, to
carry out the measure.
The vertical base is made by aluminum and the horizontal base is made by sill.
Image 20. - Vertical and horizontal bases.
Once assembled all the pieces making the checking fixture, it proceed to
collocate the grill on this, remaining as follows.
Image 21. - Checking fixture finalized
ESTIMATED COST ANALYSIS VS REAL COST
Estimated Cost Analysis Indirec Costs Quantity Hours Unit price Total Materials
sandpaper 100 2 N/A $ 11.70
$ 23.40
sandpaper 50 2 N/A
$ 17.40
$ 34.80
wire brushing 1 N/A
$ 143.00
$ 143.00
Cobalt Steel Square Tool (cutter)1/2" 1 N/A
$ 569.24
$ 569.24
paintbrush 2" 1 N/A
$ 16.20
$ 16.20
Tools and equipment $ 786.64
drill bits 1 N/A $ 500.00
$ 500.00
welding electrodes 6011 1 N/A
$ 295.00
$ 295.00
Polisher 1 N/A
$ 1,500.00
$ 1,500.00
milling machine 1 3
$ 381.00
$ 1,143.00
welding machine 1 N/A
$ 3,000.00
$ 3,000.00
Soldering iron 1 N/A
$ 84.00
$ 84.00
USB pic programmer 1 N/A
$ 270.00
$ 270.00
Software $ 6,792.00
Labview 2016 1 N/A $
1,859.00 $
1,859.00
SolidWorks 1 N/A $ - $ - $ 1,859.00
Indirects costs $ 9,437.64
Direct Costs Quantity Hours Unit price Total Materials
Screw: 1/2" x 2" hex head 30 N/A $ 9.68
$ 290.40
steel plate 3/8" 45cmx1.83m 1 N/A
$ 1,286.21
$ 1,286.21
dial indicator, standard 1 N/A
$ 3,842.27
$ 3,842.27
Vertical Hasp 2 N/A
$ 312.35
$ 624.70
aluminium square rod1 1/2 "x 1 1/2" 20" alto 1 N/A $ $
298.12 298.12
black polyurethane varnish 1 1/2 L 1 N/A $ 152.00
$ 152.00
Plated Steel Flat Bar1/8" x 1 1/2" 3 mts large 1 N/A
$ 270.00
$ 270.00
Pic 16F877A 1 N/A
$ 136.00
$ 136.00
Webcam Acteck Atw-1200 high definition usb 1 N/A
$ 315.00
$ 315.00
Jumper wire female/male extension 10 cm 15 N/A
$ 4.00
$ 60.00
Jumper wire female/male extension 15 cm 15 N/A
$ 4.00
$ 60.00
telephone cable 2 N/A
$ 4.50
$ 9.00
tin welding (meter) 1.5 N/A
$ 6.00
$ 9.00
solder paste 1 N/A
$ 19.00
$ 19.00
Copper plate 15x20 cm 1 N/A
$ 48.00
$ 48.00
Labor $ 7,419.70
Mecatronic engineer 1 6 $
104.17 $
625.00
Mechatronics technician 1 16 $
36.46 $
583.33
mechanical engineer (design) 2 12 $ 62.50
$ 1,500.00
Welder 1 48
$ 13.67
$ 656.04
mechanical auxiliar 2 48 $ 39.06
$ 3,749.76
$ 7,114.13
Direct costs total $ 14,533.83
Indirect costs + Direct costs $ 23,971.47
Estimated Cost Analysis Indirec Costs Quantity Hours Unit price Total Materials sandpaper 100 2 N/A $ 11.70 $ 23.40
sandpaper 50 2 N/A $ 17.40 $ 34.80 wire brushing 1 N/A $ 143.00 $ 143.00 Cobalt Steel Square Tool (cutter)1/2" 1 N/A $ 569.24 $ 569.24 paintbrush 2" 1 N/A $ 16.20 $ 16.20
Tools and equipment $ 786.64
drill bits 1 N/A $ - $ - welding electrodes 6011 1 N/A $ - $ - Polisher 1 N/A $ - $ - milling machine 1 3 $ - $ - welding machine 1 N/A $ - $ - Soldering iron 1 N/A $ - $ - USB pic programmer 1 N/A $ - $ -
Software $ -
Labview 2016 1 N/A $ - $ -
SolidWorks 1 N/A $ - $ - $ -
Indirects costs $ 786.64
Direct Costs Quantity Hours Unit price Total Materials Screw: 1/2" x 2" hex head 30 N/A $ 9.68 $ 290.40 steel plate 3/8" 45cmx1.83m 0.5 N/A $ 1,286.21 $ 643.11 dial indicator, standard 1 N/A $ 3,842.27 $ 3,842.27 Vertical Hasp 2 N/A $ 312.35 $ 624.70 aluminium square rod1 1/2 "x 1 1/2" 20" alto 1 N/A $ 298.12 $ 298.12 black polyurethane varnish 1 1/2 L 1 N/A $ 152.00 $ 152.00 Plated Steel Flat Bar1/8" x 1 1/2" 3 mts large 1 N/A $ 270.00 $ 270.00 Pic 16F877A 1 N/A $ 136.00 $ 136.00 Webcam Acteck Atw-1200 high definition usb 1 N/A $ 315.00 $ 315.00 Jumper wire female/male extension 10 cm 10 N/A $ 4.00 $ 40.00 Jumper wire female/male extension 15 cm 10 N/A $ 4.00 $ 40.00 telephone cable 2 N/A $ 4.50 $ 9.00 tin welding (meter) 1.5 N/A $ 6.00 $ 9.00 solder paste 1 N/A $ 19.00 $ 19.00 Copper plate 15x20 cm 1 N/A $ 48.00 $ 48.00
Labor $ 6,736.60
Mecatronic engineer 1 6 $ 104.17 $ 625.00 Mechatronics technician 1
$ 36.46 $ -
mechanical engineer 2 12 $ 62.50 $ 1,500.00 Welder 1 48 $ 13.67 $ 656.04
COMPARATIVE
Estimated Cost Analysis Real Cost
Materials $ 786.64 Materials
$ 786.64
Tools and equipment
$ 6,792.00
Tools and equipment $ -
Sotware $ 1,859.00 Sotware $ -
Indirect costs $ 9,437.64 Indirect costs
$ 786.64
Materials $ 7,419.70 Materials
$ 6,736.60
Labor $ 7,114.13 Labor
$ 6,530.80
Direct Costs $ 14,533.83 Direct Costs
$ 13,267.40
Total Cost $ 23,971.47 Total Cost
$ 14,054.04
*Note 1: the cell without price is because the university had the tool, equipment or software and it doesn't represent a cost for us. * Note 2: The members of the team did all the labor but the classification of the work was according with activities that they develop and the cost is just an estimate of what could cost outside the project.
mechanical auxiliar 2 48 $ 39.06 $ 3,749.76 $ 6,530.80
Direct costs total $ 13,267.40
Indirect costs + Direct costs
$ 14,054.04
CONCLUSION
Within the commercial industry, it's very important to know the processes that
are carried out within the company, if this processes are known we can find the
answer to many questions such as: how many pieces are produced per hour?
What is the cost of producing those parts in one hour? In addition, another
aspect to take into account is the quality of our elaborated product. For this
reason, complying with established standards is necessary so that production
does not diminish, it avoids rejections by quality control, that is always involved
in the manufacturing processes and increase the company profits.
The automotive industry has a complexity in its processes that makes really
important the inspections of the elements manufactured to meet the quality
standards that are required.
With the development of a checking fixture system to be implemented within the
company, great benefits are obtained, such as reducing the analysis times of
the parts, and then the quantity of manufactured parts increases considerably.
Throughout the project there were many important considerations to create the
right design. Establishing the facility to handle the checking fixture was
extremely important to maximize the benefits sought. In the same way, the
collection of the information obtained with this device raised an important point
to determine the functionality of the system.
Considering the above mentioned, and after having realized the design of the
checking fixture developed during this project, it is summarized that the
industry, especially the automotive industry, will obtain better results in its
processes thanks to the implementation of these measurement devices.
LESSONS LEARNED
The establishment of lessons learned throughout a project is a stage in the
process that can't be omitted. For this reason, the lessons learned by the work
team are listed as follow.
Knowledge of GD&T.
Thanks to the training provided for the development of the project, the entire
team acquired knowledge about these areas of metrology.
Programming of activities for the project development.
It was necessary to establish priorities in this project to achieve the established
goal on the checking fixture development. Based on the main activities, the
project could be monitored.
Quotation of materials for the project development.
For some of the team members it was a completely new experience to observe
the quote process for the purchase of the materials to be used.
Measurement of the piece.
Establishing the correct real measurements of the piece assigned to us was a
process through which we had to determine the optimal ways to measure the
most complex areas.
General sizing symbols.
As we had mentioned earlier, the team received training during the project.
During one of them, we could understand the meaning of many symbols of
general dimensioning that until now were unknown for us.
Reverse engineering
It is the process carried out of extracting design information from the Chevy c1's
component, something that is already man-made, and with this information we
can create something new, the checking fixture in this case.
Design objectives.
For the checking fixture creation, it was necessary to define the objectives of
our design from the beginning. The first objective that had to be fulfilled was the
establishment of the general idea for the final product. In the same way, the
issue of costs of preparing the checking fixture was significant in the search for
optimization to minimize costs, as well as the knowledge of the technologies
that were available to us to formulate the steps of the project development.
Take into account the lessons learned from the project gives us a greater
benefit, gives us more experience to carry out future projects and also
increases the value of our participation in this project.
BIBLIOGRAPHY
Colvin, Fred H.; Haas, Lucian L. (1938). Jigs and Fixtures: A Reference
Book. New York and London: McGraw-Hill Book Company.
Henriksen, Erik K. (1973). Jig and Fixture Design Manual. New York, N.Y.:
Industrial Press Inc.
ABC Group (2014). Checking fixture/ Gauge standard. Toronto, Ontario:
ABC Group.
Barrera, Adriana; Pulido, Alejandro (2016). The Mexican automotive
industry: current situation, challenges and opportunities. Mexico City:
ProMéxico.
ASME Y14.5M, Dimensioning and Tolerancing.
McCale, Michael R. (1999). "A Conceptual Data Model of Datum
Systems" (PDF). Journal of Research of the National Institute of Standards
and Technology.
Henzold, Georg (2006). Geometrical Dimensioning and Tolerancing for
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