sliding lens holder report (mate junior series)

8/3/2019 Sliding Lens Holder Report (Mate Junior Series)

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Sliding Lens Holder Final Review

Team Yellow

Dillon Lynch

Mate 340

December 6, 2010


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Introduction:

The goal of this project is to create a Lens Holder capable of taking accurate measurements of Liquid

Crystal Displays (LCDs). The light sources provided will either be Light Emitting Diodes (LEDs) or Backlit

filters. Team Yellows specific assignment is narrow band filters and the design is based on the use of a

backlit light source, in this case a quartz halogen light. The Light Measurement System (LMS) must be

able to mimic the human eye and thus be able to pick up and process a variety of colors. The light will

pass through red, green and blue filters where it will then be compared against a set of values received

using calibrated RGB dichroic filters. This is done in order to see how closely these values are too values

of a traditional CRT display. Consumers have become used to colors used in CRTs and therefore the

industry would like values for LCD displays to match as closely as possible.

User Needs:

The light measurement system has a variety of specific needs. In order to address these needs they were

separated into 7 performance goals being; Stability, Operation, Schedule, Ergonomics, Manufacturability,

Cost and safety. These goals were then given measurable objectives and a weighting factor as shown

below in table I. Stability is necessary in order to gain accurate readings and ensure repeatability over the

course of one hour, and reproducibility over the course of 5 days. Operation entails the alignment,

calibration and sample insertion of the sample. The sample must be aligned properly in order to take valid

measurements, must only require calibration once a day and should take less than a minute to load.

Schedule requires that the prototype must be completed and tested in 11 weeks. Ergonomics dictates

that the prototype must be easy to use and assemble and remain relatively small. It mus be manufactured

from cast Al 356 aluminum and abs plastic. The cost must remain below $500. And in order to remain

safe light must remain inside the LMS and there should be no sharp edges.


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Table I

Attributes Measureable Objectives Weighting FactorStability, Precision +/- .04 repeatability (1hr)

+/- .1 reproducibility (1 week)Spectral measurement time


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Conceptual Design Solutions:

During brainstorming two designs were created and discussed. One was a slide design that used a

sliding ABS Part that swapped out lenses in order to meet the design specifications of creating a stable

yet easily adjustable. The second design was a box and lid design in which the lens was placed then

enclosed in the two Al parts. The designs are shown in figures 2 and 3 respectively. A design matrix

(Table II) was used to determine the best design. After comparing the two the slide design was the clear

choice due to a higher total value in the decision matrix and became the primary design. This was

primarily due to the advantages in stability and operation provided by the slide. It had an operation value

of 9.5 versus the box designs value of 6 ( TableII ). This was due primarily to the ability to easily switch

out the three filters thus making sample insertion much faster. The slide also had a higher stability and

precision value due to the fact that the slide would align directly centered inside the filter holder with

collimator and focusing lens on either side.

Figure 1 System Block Diagram


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Table II

Conceptual Design Matrix

Box Slide

Attributes Score Weight Value Score Weight ValueStability andPrecision

6 3.5 21 8.5 3.5 29.75

Operation/Alignment 6 2.5 15 9.5 2.5 23.75Schedule 10 1.5 15 10 1.5 15Ergonomics 8 1 8 9.5 1 9.5Manufacturability 7 .75 5.25 6.5 .75 4.875Cost 8 .5 4 8 .5 4Safety 10 .25 2.5 10 .25 2.5Total - - 70.75 - - 89.375

Figure 2 Slide design holder plus slide


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Figure 3: Box design with sliding lid

Design Specifications:

The light source used must be an LS-1 tungsten-halogen light which produces a spectrum from 360-

1100 nm and generates approximately 1 milli-watt/cm2 @ 550nm. The Lens holder must be made of heat

treated T6 Al 356, The volume of the mold is approximately 866.33 cm3,

with the filter holder and gating

having a combined volume of 170 cm3. The slide was rapid prototyped from ABS Plastic with an

approximate volume of 36.533 cm3.The adjuster were also rapid prototyped and contain a volume of

approximately 10.30 cm3. The fiber optic cables will be made from 200m diameter fibers and must be

able to let light pass through with minimal loss. The spectrometer is an Ocean Optics USB4000 VIS-NIR

fiber optic spectrometer it has a 600 g/mm grating and a 350-1000nm spectral range. An exploded view

(Figure 4) is provided allowing to see how the LMS system is assembled


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Figure 4 Exploded View of LMS containing all parts

Fabrication and Assembly:

Metallurgical Analysis of Cast LMS Base:

Casting Process:

The LMS lens holder was cast from Al 356 an alloy this alloy consists of 6.5% Si, 0.3% Mg, and 0.2% Fe

and 93% Al. Al 356 is a favorable element due to its high fluidity and feeding ability, which is due to the

silicon present in the alloy. In order to begin casting a mold was created using Solidworks and printed

using ZCast 501. After creating the base, the Al 356 was melted in a furnace set for 720C. The base

was then held in placeby sand as the alloy was poured into the mold until the risers had filled (Figure 5).

The volume for the base and gating was calculated to be 170 cm3. Afterwards the base was allowed to

cool for several hours, after which the ZCast was removed and the cast base was machined to remove

the risers and gating.


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Figure 5 Peter Pouring the Al 356 into the ZCast mold

Heat Treatment:

The LMS base need to be heat treated after being casted. T6 heat treatment was used in order to

increase the strength of the bas this means the Al 356 was solution heat treated and artificially aged2. T6

is used primarily for alloys that are not cold worked after solution heat treatment, so that mechanical

properties, dimensional stability, or both, can be substantially improved by precipitation heat treatment2.

After deciding that the ZCast method most closely resembles sand casting the treatment required that the

Al 356 alloy must be solution heat treated at 350C for twelve hours. After being solution heat treated the

base was quenched then placed back in the furnace this time set at 155C for three hours. In order to

verify the heat treatment had been successful pieces of the heat treated and as cast gating were

hardness tested. The T6 heat treated sample had an average hardness value of 57.1 HRB with a

standard deviation of 2.37 HRB. The as cast Al 356 had a hardness value of 55.8 HRE and a standard

deviation of 2.03 HRE. All measurements can be seen in Table III. Since HRE is on a different scale then

HRB the as cast part is HRB equivalent hardness is approximately 39.06 HRB. After conducting a two

sample t-test it is proven that the T6 heat treated alloy is significantly harder than the as cast part. Since


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the T6 part was harder than the as cast part, and matched the standard hardness values of standard heat

treated T6 Al 356 it can be concluded that the heat treatment was successful.

Table III: Hardness Measurements

Hardness Values

As- Cast

(HRE)

T6

(HRB)

54.1 54

53.3 56.9

56.9 56.5

58.2 57.6

56.4 60.6

63.4

62.6

56.9

Average 55.78 58.56

Microstructures:

The microstructures of both the as cast and T6 heat treated Al 356 alloys were observed from pieces of

the gating. The alloy was cast at 750C allowed to cool at room temperature then T6 heat treated as

described above (figure 6).During equilibrium cooling, proeutectic alumunum forms before the alloyreaches the eutectic temperature. Once the alloy is cooled below the eutectic temperature the remaining

liquid forms into a lamellar structure. In the as-cast micrograph (figure 7) there are oval like white areas,

this is the proeutectic aluminum. The dark grey rods are the interdendritic silicon that forms after the

passing the eutectic temperature. The grey colored speckles within the aluminum matrix are silicon

precipitates that form due to supersaturation. The light grey blade regions are some unidentified Si

compound. After solution heat treating, the proeutectic aluminum is no longer able to be seen and the

non-strengthening silicon precipitates dissolve. The silicon interdentritic particles spheroidize due to the

heat treatment (figure 8), however, the unidentified silicon compounds stay in the same shape


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Figure 6: The Al-Si phase diagram. 7 percent of Si is present in A356 Al alloy, the red dot shows what

temperature the alloy was cast at. Blue shows the temperature it was solution heat treated at and green

shows the temperature it was aged at.

A. B.

C. D.

Figure 7: As-Cast A356 Al unetched, A. 5x, B. 10x, C. 20x, D. 50x.


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A. B.

C. D.

Figure 8: T6 A356 Al unetched, A. 5x, B. 10x, C. 20x, D. 50x.

Testing Methodology:

The first step in testing the finished lens holder would be to assemble the holder with the lens removed.

The fiber optic cables would then be aligned properly in order to maximize light passage. Next the

spectrometer needs adjusted to the light source. The following step is to remove the filters remove filters,

activate light source and spectrometer, allowing the unfiltered light to be picked up by spectrometer.

Using spectrasuite calibrate the spec to 100% transmission with an integration time of 300 milliseconds.


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Once adjusted so that there are no peaks the filters can then be loaded. To obtain chromaticity values

upload the data received from spectrasuite into excel along with 1931 CIE chromaticity scale. Using excel

sum all transmission, and tristimulous values to find the x, y, and z from the filters. To measure

reproducibility 6 measurements must be taken in an hour and statistical analysis is used to determine

standard deviation if the calculated value is less than .04 it is reproducible. Repeatability is tested by

having multiple testers retest the spectrometer over 5 days then use statistical analysis to f ind a standard

deviation if the standard deviation is below .1 then the process is repeatable. In order to make the testing

process more accurate we would make sure all group members are familiar with the standard operating

procedures before allowing them to test the LMS.

Project Plan:

The first step in completing the project was to assign every member of the group a specific job. Marissa

became Team leader/Gant chart, Tom develops all the standard operating procedures, Sam is assigned

to functional requirements and specifications, Peter is responsible for the bill of materials and I was

assigned to do all the drawings. The first step of the project was to identify all the parts necessary and

which design we were going to use. After the slide design was chosen I began work on all the drawings.

Sam then decided all the specifications needed. Peter created a projected budget and maintained our

current bill of materials. Marissa created the Gant chart. Tom created the procedure to accurately

measure the incoming light. The fiber Optic cabling was made with all members of the group. After the

CAD drawings were finished the mold and casting were done as a team and the ABS part was created.

The next step was for Brian to machine the rough parts to the exact specifications. As a team the pieces

were be assembled, then Tom tested the parts and as a team adjustments were made and the final lens

holder completed. The project was completed in 11 weeks. This is listed in further detail in the Gant Chart

(Figure 6) and Table III.


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Table III

Cost analysis analysis:

We had a budget of 500 dollars which we were far below and after calculating all the manpower hours we

calculated a total man power cost of $ 33,175. This could be easily reduced by having less people doo

each task as the entire group wasnt needed to complete most of the work. (figure ()

Figure 8 Gant chart with assigned roles and times


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Figure 9 cost analysis

Conclusion and Color analysis:

The narrow band filters did not match the phosphor color values even though the angular offset was

almost nonexistent though the distance offset was great enough to cause them to be statistically different

as shown in Table IV. Our Filters were however statistically similar to the dichroic filters and last years

data as shown in figures 10 and 11 and table V. Table VI shows that we met our needs for reproducibility

and repeatability. In conclusion Narrow band filter are not the best choice to replace CRTs due to their

color values yet the light measurement system meets the all the user needs and is thus able to take

successful measurements.


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Table IV

NB

(Y/X)

Phosphor

(Y/X)

Angular

Offset

Distance

Offset

Red 0.432 0.432 0% 0.113

Green 2.089 2.088 1.07% 0.007

Blue 0.811 0.811 0% 0.005

Figure 10 Chromaticity trending showing values from both clases vs the standard

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

red x

red y

green x

green y

blue x

blue y

Chromaticity Value

ColorCooridinate

Chromaticity Trending

Class 2009

Yellow 2010

Standard


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Table V

2009 2010 P-value Match

Red X 0.634 0.736 .023 No

Red Y 0.269 0.318 .008 No

Green X 0.31 0.316 .386 Yes

Green Y 0.612 0.66 .058 Yes

Blue X 0.136 0.132 .174 Yes

Blue Y 0.111 0.107 .111 Yes


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Table 6

Repeatability Reproducibility

Target

2

Actual 2 Target 2 Actual 2

Red x


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Sources

(1)Ashby , Michea l , Hugh Scherc l i f f , and Dav id Cebon. Mater ia ls

eng ineer ing , sc ience , p rocess ing and des ign . 2nd . Ox fo rd :

But tewor th -He inemann, 2007. Pr in t .

( 2 ) "Temper Des igna t i ons f o r Hea t - T r ea t ab le A luminum A l l oys . " ASM Handbooks

On l i ne 4 . ( 2002 ) : n . pag . ASM Handbooks On l i ne . Da t abase . 6 Dec 2010 .

.

0

10000

20000

30000

380 480 580 680

C

ounts

Wavelength (nm)

Red Filter

0

20000

40000

60000

380 480 580 680

Counts

Wavelength (nm)

Green Filter

0

5000

10000

15000

380 480 580 680

Counts

Wavelength (nm)

Blue FilterFigure 11 measured color values

sliding lens holder report (mate junior series)

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