This research investigated the effects of processing conditions on the shrinkage and warpage (S&W) behavior of a box-shaped, polypropylene part using conventional, microcellular, and microcellular co-injection molding. Three sets of 26-1 fractional factorial design of experiments (DOE) were employed to perform the experiments and proper statistical theory was used to analyze the data. After the injection molding process reached steady state, molded samples were collected and measured using an optical coordinate measurement machine (OCMM), which had been evaluated using a proper repeatability and reproducibility (R&R) measurement study. By analyzing the statistically significant main and two-factor interaction effects, the results show that the supercritical fluid (SCF) content (nitrogen in this case, in terms of SCF dosage time) and the injection speed affect the S&W of microcellular injection and microcellular co-injection molded parts the most, whereas pack/hold pressure and pack/hold time have the most significant effect on the S&W of conventional injection molded parts. Also, this study quantitatively showed that, within the processing range studied, a reduction in the S&W could be achieved with the microcellular injection molding and micro- cellular co-injection molding processes.

1.
Chandra
A.
,
Gong
S.
,
Yuan
M.
,
Turng
L. S.
,
Gramman
P.
, and
Cordes
H.
,
Polym. Eng. Sci.
,
45
,
52
52
(
2005
).
2.
Chandra
A.
,
Gong
S.
,
Turng
L. S.
, and
Gramman
P.
,
J. of Cellular Plastics
,
40
,
371
371
(
2004
).
3.
Kharbas
H.
and
Turng
L. S.
,
International Polym. Proc.
,
19
,
77
77
(
2004
).
4.
Yuan
M.
,
Turng
L. S.
,
Caulfield
D.
,
Hunt
C.
, and
Spindler
R.
,
Polym. Eng. Sci.
,
44
,
673
673
(
2004
).
5.
Kharbas
H.
,
Nelson
P.
,
Yuan
M.
,
Gong
S.
,
Turng
L. S.
, and
Spindler
R.
,
Polymer Composites
,
24
,
655
655
(
2003
).
6.
N. P. Suh, in Innovation in Polymer Processing-Molding, J.F. Stevenson (ed.), Hanser Publishers, Munich, 93 (1996).
7.
Park
C. B.
,
Doroudiani
S.
, and
Kortschot
M. T.
,
Polym. Eng. Sci.
,
38
,
1205
1205
(
1998
).
8.
Shimbo
M.
,
Baldwin
D. F.
, and
Suh
N. P.
,
Polym. Eng. Sci.
,
35
,
1387
1387
(
1995
).
9.
Seeler
K. A.
and
Kumar
V.
,
J. Reinforced Plastics and Composites
,
12
,
359
359
(
1993
).
10.
Kwag
C.
,
Manke
C. W.
, and
Gulari
E.
,
J. Polym. Sci., Part B: Polym. Phys.
,
37
,
2771
2771
(
1999
).
11.
Royer
J. R.
,
Gay
Y. J.
,
Desimone
J. M.
, and
Khan
S. A.
,
J. Polym. Sci., Part B: Polym. Phys.
,
38
,
3168
3168
(
2000
).
12.
Kwag
C.
,
Manke
C. W.
, and
Gulari
E.
,
Ind. Eng. Chem. Res.
,
40
,
3048
3048
(
2001
).
13.
Zhang
Z.
and
Handa
Y. P.
,
J. Polym. Sci., Part B: Polym. Phys.
,
37
,
977
977
(
1998
).
14.
Handa
Y. P.
,
Kruus
P.
, and
O’Neill
M.
,
J. Polym. Sci., Part B: Polym. Phys.
,
34
,
2635
2635
(
1996
).
15.
Turng
L. S.
,
J. Injection Molding Tech.
,
5
,
160
160
(
2001
).
16.
Xu
J.
and
Pierick
D.
,
J. Injection Molding Tech.
,
5
,
152
152
(
2001
).
17.
Trexel, Inc., Website: http://www.trexel.com/.
18.
N. Santhanam, “Analysis of residual stresses and postmolding deformation in injection–molded components,” Ph.D. thesis, Cornell University, Ithaca, New York (1992).
19.
Santhanam
N.
,
Chiang
H. H.
,
Himasekhar
K.
,
Tuschak
P.
, and
Wang
K. K.
,
Adv. Polym. Technol.
,
11
,
77
77
(
1992
).
20.
Park
C. B.
and
Cheung
L. K.
,
Polym. Eng. Sci.
,
37
,
1
1
(
1997
).
21.
D. C. Montgomery, Design and Analysis of Experiments, John Wiley & Sons, New York, (1997).
22.
D. S. Ermer and R. Y. E-Hok, Contributed Publications of the Measurement Quality Division, American Society for Quality, 2 (1997).
23.
D. J. Wheeler and R. W. Lyday, Evaluating the Measurement Process, SPC Press, Inc., Knoxville, (1989).
This content is only available via PDF.
You do not currently have access to this content.