Warpage Analyses On Ultra Thin Shell Biology Essay

Warpage is ever considered as a common issue related with injection modeling procedure and ever be the chief mark by mold interior decorators to avoid it. Increasingly hard to command warpage with excessively thin plastic merchandises. Therefore many researches and publications were made on this subject intentionally to analyze the most important factors influence warpage in plastic parts. In this survey, an extremist thin shell fictile merchandise is decided to be a topic of analysis. The portion with dimension aa x BB x milliliter and thickness Doctor of Divinity is evaluate by utilizing border gate. Thermoplastic Polycarbonate/Acrylonitrile Butadiene Styrene ( PC/ABS ) is used as a fictile stuff. Taguchi Method is applied in placing the optimal value of injection modeling parametric quantities and Moldflow Plastic Insight package is used to imitate the injection modeling procedure.

Two experiments have conducted to compare the consequence of warpage in extremist thin shell parts with same and differences temperature in nucleus and pit home base ( mold temperature ) . The consequences shows the different temperature on nucleus and pit home bases has no important factors in extremist thin shell parts molded but mold temperature is the most important factor in extremist thin shell parts. This determination is perfectly a good thing to larn of warpage consequence in the extremist thin shell produced.

Injection Molding Process is defined as a procedure used in bring forthing plastic-based merchandises. Efficiency of the injection modeling procedure is extremely influenced by right scenes of peculiar procedures. This procedure by and large begins from the phase of planing plastic parts, followed by planing casts, manufacturing casts, and puting parametric quantities before an injection modeling procedure takes topographic point and this causes a figure of unwanted defects such as dyer’s rocket lines, warpage, sink Markss which cut down value of the shaped constituents.Equally far as quality is concerned, warpage is one of common effects on shaped parts. It is of import for the merchandise design applied scientist to imitate the warpage consequence during design procedure to minimise the alteration cost on the cast and to maximise the quality of parts bring forthing. Many researches and publications were made on this subject, both on theoretical simulation and on experimental consequences to analyze the behaviour of warpage occurred at molded parts.

Tang [ 1 ] has applied Taguchi method to minimise warpage on thin home base parts. The gate dimension and the mold temperature were eliminated while ANOVA was used to find the most important factor affected warpage. As a consequence, runing temperature was found to be the most of import factor that contributes to the being of warpage.Huang and Tai [ 2 ] studied the effects of warpage that is seen in thin shell parts produced by injection modeling utilizing simulation package. Taguchi method used to find the optimal value of injection parametric quantities and this led to a determination that packing force per unit area is the most important factor that affects warpage and gate locations every bit good as make fulling clip have merely little effects over warpage.

A consequence acquired by Liao et Al. [ 3 ] besides agrees that packing force per unit area is the most influential parametric quantity in injection molding procedure. His survey was done intentionally to find the reactions of a thin walled portion harmonizing to shrinking and warpage issues where mould temperature, melt temperature, packing force per unit area and injection velocity were taken as the injection parametric quantities [ 4 ] . From the research, it is found that packing force per unit area is a large factor contributes to the happening of warpage.Z.Shayfull et Al. [ 5 ] proved that the temperature differences of the nucleus and pit sides have effects on the quality of fictile portion molded.Yu et Al.

[ 6 ] have studied the injection casting of thin home bases of micro sized characteristics. Zhao et Al. [ 7 ] and Shen et Al. [ 8 ] have investigated the effects of the procedure parametric quantities on the micromolding procedure and portion quality, nevertheless, probes for extremist thin shell injection casting is seldom to be reported.

M.C. Song et Al. [ 8 ] have explored effects of injection procedure parametric quantities on the casting procedure for extremist thin wall plastic parts.

The ultra-thin wall fictile portion is a peculiar sort of micro plastic parts. It is conventionally defined as the portion that have a nominal wall thickness of 1mm or less and a surface country of at least 50 cm2 with a flow length/thickness ratio above 100 or 150.Equally far as this issue is concerned, the challenge for the fabrication applied scientists presents is to bring forth extremist thin molded parts at minimal warpage. The purpose is to happen out the most influential factor in extremist thin shell injection casting, so as to cut down the times of test casting, better portion quality and can be a mention in farther probe of modeling defects ( warpage, weld line, e.g.

) of extremist thin shell plastic parts.GATING SYSTEM DESIGNProduct design applied scientists should be able to place types of to be used. It can be allocate at the surface which user ca n’t see the gate Markss after assembly. However sometimes it had to be placed on decorative surfaces and usually it will covered by lodging label.

Fig. 1 shows a thin shell parts ( A x B x C ) millimeter with thickness XX millimeter and gating system with pin point gate ( three-plate cast ) .

`

The inside informations of gating system with complete dimensions are shown in inside informations in Fig. 2.Fig. 3 shows the chilling channel with O6mm designed for the cast.ExperimentThere are many factors that affect the quality of plastic merchandises produced from injection modeling procedure.

It includes a design of fictile merchandise, fictile stuff used, types of pit insert stuffs, types of machines, machine parametric quantities, coolant design, coolant size, coolant liquid and room temperature. In this survey, merely a few major factors are taken into considerations and some premises are made which are ;Gate dimension factor is neglected because of its design is non indistinguishable for every portion.The temperature of the environment is assumed changeless.The coolant is assumed as pure H2O.The effects of other minor factors ( Other than runing temperature, mold temperature, make fulling and packing procedures ) are non to be under the subject of treatment.The layout of the chilling channels is assumed to keep a changeless temperature.

The effects due to the form and size of the cast and merchandise are neglected due to assorted forms of merchandise.The fictile stuff used in all of the simulations is formless thermoplastic PC/ABS blend, Cycoloy C2950HF from GE. Its viscousness is between 102 and 104 poise where the shear rate is in 102-103 s-1 scope. The scope of thaw temperature is between 220 oC and 400oC about.Basic physical and mechanical belongingss of PC/ABS are shown in Table 1.

Table 1: The physical belongingss of PC/ABSSpecific heat, Cp ( J/kgoC )1871Glass passage temperature, Tg ( oC )112Thermal enlargement coefficient, I± ( mm/moC )74Elastic modulus, E ( MPa )2.63 x 103Poisson ‘s ratio, I…0.23Thermal conduction, K ( w/moC )0.27Fig. 4 shows the two pits of thin shell generated with 67,270 pieces of 1mm length triangular.Two experiments have been conducted to acquire the best scene parametric quantities and to find the most important factors affected warpage on extremist thin shell parts. Four factors ( A-D ) are identified to be controlled in Experiment-I and five factors ( A-E ) controlled in Experiment-II. L9 34 is chosen for experiment-I and L16 45 are chosen for experiment-II.

These extraneous array discrepancy and parametric quantities control factors are shown in Table 2, 3,4,5,6 and 7 severally. The differences between Experiment-I and II is Experiment-I considered merely mold temperature, that means the temperature nucleus and pit side is same but Experiment-II considered the different temperature for pit and nucleus side. The injection clip is set 0.1s. This is because, from the simulation, if the injection clip more than 0.1s, some of combination parametric quantities will ensue short-shot on the shaped parts.The Signal-to-noise ( S/N ) ratio is calculated harmonizing to consequences ( warp in z-direction ) signifier warpage analysis of thin shell home base as shown in Table 8 and 9 in order to obtain the best parametric quantity puting agreement. From this technique, the per centum of part is calculated in finding which of the factor has important consequence on portion ‘s warpage.

Table 2: The three degree of effectual factor for experiment-I discrepancy

Factor

Degree

1

2

3

Mold temperature, A ( A°C )

607080

Melt temperature, B ( A°C )

260270280

Packing force per unit area, C ( MPa )

70 %80 %90 %

Packing clip, D ( s )

0.70.80.9Table 3: The four degree of effectual factor for experiment-II discrepancy

Factor

Degree

1

2

3

4

Mold temperature, A ( A°C )

65707580

Core temperature, B ( A°C )

65707580

Melt temperature, C ( A°C )

265270275280

Packing force per unit area, D ( MPa )

75 %80 %85 %90 %

Packing clip, E ( s )

0.750.800.850.

90Table 4: L9 Orthogonal array discrepancyfor experiment-I

Trial No.

Control Factor

A

Bacillus

C

Calciferol

1

1111

2

2122

3

3133

4

1223

5

2231

6

3212

7

1332

8

2313

9

3321Table 5: L16 Orthogonal array discrepancyfor experiment-II

Trial No.

Control Factor

A

Bacillus

C

Calciferol

Tocopherol

1111112122223133334144445212346221437234128243219313421032431113312412342131341423144231415432411644132Table 6: The combination parametric quantities for the control factors for experiment-I

Trial No.

Control Factor

A

Bacillus

C

Calciferol

1

60260700.7

2

70260800.

8

3

80260900.9

4

60270800.9

5

70270900.7

6

80270700.

8

7

60280900.8

8

70280700.9

9

80280800.7Table 7: The combination parametric quantities for the control factors for experiment-II

Trial No.

Control Factor

A

Bacillus

C

Calciferol

Tocopherol

16565265750.7526570270800.8036575275850.

8546580280900.9057065270850.9067070265900.8577075280750.

8087080275800.7597565275900.80107570280850.75117575265800.90127580270750.85138065280800.85148070275750.

90158075270900.75168080265850.80The warp of thin shell parts in z-direction obtained from the simulation procedure are besides analyzed utilizing Analysis of Variance ( ANOVA ) where the degree of assurance is set at 0.05.

The consequences from ANOVA are compared with SN ratio method. The interaction consequence of factors is identified and the part of each factor towards the entire consequence is analyzed.RESULT AND DISCUSSIONTable 8 and 9 show the consequences of warpage analysis ( warp in z-direction ) for thin shell parts. In this instance, ‘the smaller the better quality ‘ equation from Taguchi method is chosen.

The equation of S/N is shown below ;MSD is the average square divergence and stands for the figure of observations where, is the figure of trials in one test. The sum-up of S/N values for the warpage of thin shell parts is shown in Tables 8 and 9.Table 8: Summary of the Results of warpage in thin shell parts

Trial No.

Control Factor

Deflection

Z-Direction

S/N Ratio

A

Bacillus

C

Calciferol

1

60260700.70.065923.6223

2

70260800.80.

057924.7464

3

80260900.90.046926.5765

4

60270800.

90.053325.4655

5

70270900.70.

061724.1943

6

80270700.80.052725.5638

7

60280900.80.055925.

0518

8

70280700.90.050925.8656

9

80280800.

70.044826.9744Table 9: Summary of the Results of warpage in thin shell parts

Trial No.

Control Factor

Deflection Z-Direction

S/N Ratio

A

Bacillus

C

Calciferol

Tocopherol

16565265750.

75

0.0562

25.005326570270800.80

0.0533

25.465536575275850.85

0.

0545

25.272146580280900.90

0.0478

26.411457065270850.

90

0.0545

25.272167070265900.85

0.0546

25.

256177075280750.80

0.0517

25.730287080275800.75

0.0454

26.858997565275900.

80

0.0561

25.0207107570280850.75

0.0452

26.8972117575265800.

90

0.0536

25.4167127580270750.85

0.0488

26.2316138065280800.85

0.

0458

26.7827148070275750.90

0.

0530

25.5145158075270900.75

0.0438

27.1705168080265850.

80

0.0590

24.5830The information of warp in z-direction for the thin shell parts besides analyzed utilizing Analysis of Variance ( ANOVA ) . The comparative per centum part of all factors is determined by comparing the comparative discrepancy. Then the grades of freedom, discrepancy, F-ratio, amounts of squares, pure amount of square and per centum part are computed. The illustrations of computations are shown below and the consequences of S/N ratio for warpage in thin shell are listed in Tables 8 and 9.

Table 10: The response tabular array of S/N ratio for WARPAGE in THIN SHELL FROM EXPERIMENT-iDegree

A

Bacillus

C

Calciferol

124.713224.981825.017224.9303224.

935525.074525.728825.

0731326.371625.963925.274225.

9692Diff.1.65840.98220.71151.

0389Table 11: The response tabular array of S/N ratio for WARPAGE in Thin SHELL FROM EXPERIMENT-II

Degree

A

Bacillus

C

Calciferol

Tocopherol

1

25.538625.520225.065325.620426.

4830

2

25.779325.783326.034926.

130925.1998

3

25.891625.897425.666525.

506125.8856

4

26.012726.021226.317625.964725.

6537

Diff.

0.47410.50101.25230.

62491.2831Fig. 5 – 8 show S/N response diagrams constructed for the warpage in a thin shell ( Experiment-I ) based on informations acquired from Table 10.

Fig. 9 – 13 show S/N response diagrams constructed for the warpage in a thin shell ( Experiment-II ) based on informations acquired from Table 11.From the S/N ratio response in Tables 10 and 11, the highest value from each factor is considered the best and chosen as the finest grouping of parametric quantities. Tables 12 and 13 show the sum-up of best parametric quantity scenes for the thin shell based on Experiment-I and II. The consequences can besides be seen from S/N response diagram shown in Fig. 5-8 for Experiment-I and Fig. 9-13 for Experiment-II.

Table 12: Best scene of combination parametric quantities FOR EXPERIMENT-I

Factor

Parameters

Mold temperature, ( A°C )

80

Melt temperature, ( A°C )

280

Packing force per unit area, ( MPa )

80 %

Packing clip, ( s )

0.9Table 13: Best scene of combination parametric quantities FOR EXPERIMENT-II

Factor

Parameters

Cavity temperature, ( A°C )

80

Core temperature, ( A°C )

80

Melt temperature, ( A°C )

280

Packing force per unit area, ( MPa )

80 %

Packing clip, ( s )

0.75Furthermore the difference between degrees in Table 10 and 11 besides shows which factor is most important that give effects on warpage thin shell parts. From Table 10 for Experiment-I, the most major factor that affects on length of weld line in thin home base is mold temperature ( A ) and followed by packing clip ( D ) , melt temperature ( B ) and packing force per unit area ( C ) . Otherwise, for Experiment-II, the most major factor that affects on length of weld line in thin home base is melt temperature ( C ) and followed by packing clip ( E ) , packing force per unit area ( D ) , core temperature ( B ) and pit temperature ( A ) .Table 14: MOST SIGNIFICANT FACTORS AFFECTED ON WARPAGE THIN SHELL PARTS

Most Significant Factor

Experiment-I

Experiment-II

1.

Mold temperature ( A )Melt temperature ( C )

2.

Packing clip ( D )Packing clip ( E )

3.

Melt temperature ( B )Packing force per unit area ( D )

4.

Packing force per unit area ( C )Core temperature ( B )

5.

N/APit temperature ( A ) .The differences consequences of analysis in Table 14 are due to a different degree, and factor in the analysis that was done. In Experiment-I merely four factors are considered and the degree of factors is three, but in Experiment-II, five factors are considered and the degree of factors is four. In Experiment-II, the thaw temperature is the most important factors compared to the mold temperature in Experiment-I.

This is because, in Experiment-II, cast temperature has divide into nucleus and pit temperature to analyze the consequence of difference temperature of cast on warpage in thin shell parts. Two more simulation have been done based on best scene of combination parametric quantities in Tables 12 and 13 to acquire the really best puting combination parametric quantities in order to acquire the minimal warpage. Table 14 shows the consequences of warp z-direction for the best scene combination parametric quantities.Table 14: Best scene of combination parametric quantities

Parameters Puting

Factor

Parameters-I

Parameters-II

Mold Temperature, ( A°C )

80N/A

Cavity temperature, ( A°C )

N/A80

Core temperature, ( A°C )

N/A80

Melt temperature, ( A°C )

280280

Packing force per unit area, ( MPa )

80 %80 %

Packing clip, ( s )

0.900.

75

Deflection

Z-Direction, ( millimeter )

0.04490.0449Consequences in Table 14 shows the warp in z-direction is same if merely packing clip is changed.

So, from the experiment conducted, the best parametric quantities and warpage for thin shell parts as per Table 14.The warp z-direction informations in Tables 8 and 9 are besides analyzed utilizing Analysis of Variance ( ANOVA ) that computes the amounts of squares, grades of freedom, discrepancy and per centum part. The illustrations of computations are shown below and the consequences ANOVA of warpge in thin shell parts are summarized in Table 15 and 16.Table 15: ANOVA TABLE FOR THIN SHELL PARTS FROM EXPERIMENT-I

Beginning

degree Fahrenheit

Second

Volt

F

P ( % )

Mold Temperature, ( A°C )

2

18.300 x 10-05

9.138 x 10-05

–

50.14

Thaw

temperature, ( A°C )

2

7.034 x 10-05

3.

517 x 10-05

–

19.27

Packing

force per unit area, ( MPa )

2

3.110 x 10-05

1.553 x 10-05

–

8.52

Packing clip, ( s )

2

8.

060 x 10-05

4.031 x 10-05

–

22.08

Pooled mistake

0

0.000

100.00

Entire

8

36.500 x 10-05

Table 16: ANOVA TABLE FOR THIN SHELL PARTS FROM EXPERIMENT-II

Beginning

degree Fahrenheit

Second

Volt

F

P ( % )

Cavity Temperature, ( A°C )

3

1.

455 x 10-05

4.851 10-06

–

4.45

Core

Temperature, ( A°C )

3

1.855 x 10-05

6.

184 10-06

–

5.68

Thaw

temperature, ( A°C )

3

1.458 x 10-05

4.860 10-05

–

44.63

Packing

force per unit area, ( MPa )

3

3.

538 x 10-05

1.179 10-05

–

10.83

Packing clip, ( s )

3

1.

124 x 10-05

3.746 10-05

–

34.40

Pooled mistake

0

0.000

100.00

Entire

12

3.

267 x 10-04

The per centum of part for each factor is listed at the last column in Tables 15 and 16. The per centum part of each factor for warpage in thin shell parts can be seen clearly in Table 17.It can be observed that in Experiment-I, mold temperature contributes the most which is 50.14 % followed by packing clip 22.08 % , melt temperature 19.27 % and packing force per unit area 8.

52 % . In Experiment-II, the most contribution factors is melt temperature 44.63 % , packing clip 34.40 % , packing force per unit area 10.83 % , nucleus temperature 5.68 % and pit temperature 4.

45 % .Table 17: Summary of PERCENTAGE CONTRIBUTION for WARPAGE IN THIN SHELL PARTS

Experiment-I

Experiment-II

Parameters

%

Parameters

%

Mold Temperature, ( A°C )50.14ThawTemperature, ( A°C )44.63Packing Time, ( s )22.08Packing Time, ( s )34.40ThawTemperature, ( A°C )19.

27PackingPressure, ( MPa )10.83PackingPressure, ( MPa )8.52Core Temperature, ( A°C )5.

68Cavity Temperature, ( A°C )4.45From the consequences, it can be seen that ‘s although mold temperature is the most important factor in Experiment-I, It is no longer important factor in experiment-II when the cast temperature is divided into pit and nucleus temperature. This is proved by puting parametric quantities as Shown in Table 14. The best puting parametric quantities from Experiment-I and II is same except packing clip but the consequence of warpage for both best scene parametric quantities is same that is 0.0449mm.DecisionPrevious surveies in injection casting procedure used fixed temperature value for mold temperature ( pit temperature and nucleus temperature ) . For case, M.

C. Song et Al. [ Ten ] did non considered mold temperature in their survey in research on effects of injection procedure parametric quantities on the casting procedure for ultra-thin wall plastic parts. Tang [ 3 ] and Huang and Tai [ 4 ] maintained same temperature for pit and nucleus temperature in simulation and experimental of warpage on thin home base and thin shell home base. In contrast, this research focuses the comparing on consequence of same temperature in pit and nucleus side and consequence of difference value of temperature on nucleus and pit on thin shell parts. The decisions of the research are as follows ;Taguchi extraneous array can efficaciously cut down the figure of tests in mold testing. The effectual factors can be determined utilizing ANOVA.

For thin shell parts, consequences show that the differences pit and nucleus temperature is non a important factors as shown in Experiment-II but the mold temperature ( pit and nucleus temperature are same ) is the most important factors in part warpage as can be seen in Experiment-I.The influence of all factors that contributes to warpage has been characterized believed to be helpful in finding more precise procedure conditions in finding injection modeling parametric quantities.There are several factors affected warpage on the shaped portion such as feed systems design, chilling channel size, chilling channel places and gate sizes that need to be determined foremost in order to plan a fictile injection cast.

This survey has proven that the differences pit and nucleus side has no important effects on warpage of thin shell and simulation package can assist us cut downing clip taken to prove the cast with the optimal quality of portion produced.[ 1 ] Huang MC, Tai CC. The effectual factors in the warpage job of an injectionmolded portion with a thin shell characteristic. Journal of Material Processing Technology 110 ( 2001 ) 1-9.

[ 2 ] S.H. Tang, Y.J. Tan, S.M.

Sapuan, S.Sulaiman, N. Ismail, R.

Samin, The usage of Taguchi method in the design of platis injection mold for cut downing warpage, Journal of Material Processing Technology 182 ( 2007 ) 418-426.[ 3 ] Liao SJ, Chang DY, Chen HJ, Tsou LS, Ho JR, Yau HT, et Al. Optimum procedure conditions of shrinking and warpage of thin-wall parts. Polym Eng Sci 2004 ; 44 ( 5 ) :917-28.[ 4 ] Think Thin, Asiatic Plastics News, July/August 1996, pp. 12-14.[ 5 ] Z. Shayfull, M.

F. Ghazali, M. Azaman, S.M.

Nasir, N.A. Faris, Effect of Differences Core and Cavity Temperature on Injection Molded Part and Reducing the Warpage by Taguchi Method, International Journal of Engineering & A ; Technology, Vol: 10, 2010, pp. 133-140.[ 6 ] L.

Y. Yu, C.G. Koh, L.

J. Lee, Experimental probe and numerical simulation of injection modeling with micro-features, Polym. Eng. Sci. 42 ( 5 ) ( 2002 ) 871-888.[ 7 ] J. Zhao, R.

H. Mayes, G. Chen, Effects of procedure parametric quantities on micro casting procedure, Polym. Eng.

Sci. 43 ( 9 ) ( 2003 ) 1542-1554.[ 8 ] Y.K. Shen, S.

L. Yeh, S.H. Chen, Three-dimensional non-newtonian calculations of micro-injection casting with the finite component method, Int. Comm. Heat Mass Transfer 29 ( 5 ) ( 2002 ) 643-652.