1. Breaking Force Analysis Report
for 5042-7293 Vcsel Lower
Housing Black (FL)
Burn mark defects
2. Burn mark
Flow mark
Defects highlight:
Defects List:
Burn mark
Flow mark
Defects Quantity:
800 pcs in Hi-Optel
50kpcs in Enplas warehouse
3. Root Cause Investigation
Enplas checked in-house stock and found all condition are same as
picture below.
Flow Mark
Flow line formed at points or areas where
divergent flows of molten resin meet inside
the cavity.
Note:
{{Avago define flow mark would not affected
the part functionality, so part is safe to use}}
Burn mark
While the molten resin flows crowed to bursting point
inside the cavities and gas cannot be released/escape
from gas venting points will gets transformed into
something similar to charcoal on the surface of a
molded part we called it welding mark.
Note:
{{Avago worry for the burn mark will weaken the part
strength, request for Breaking force reference test}}
Explanation on defects formation:
4. Breaking test on burn mark area refer to normal sample
Conducted breaking test
Enplas conduct a breaking force test to
check weather burn mark will weaken the
part strength.
Normal (Reference)
sample
Burn mark sample
Null Hypothesis H0: All the break force groups have equal stress on the average
5. Breaking test work instruction
Placed properly the “L” rib of part to be tested
Set “zero”
6. Operate the push gauge
down until the rib broken
Left(L) Rib
Breaking test work instruction
9. Breaking test data analysis
2.500 2.700 2.900 3.100 3.300 3.500 3.700
Reference
Burn
Breaking Force in KgF
TestSamples
The Breaking Force of Burn Mark spot reference with
normal part in KgF
The median gap value between 2 sets
samples breaking force are small
(0.65% differences).
Reference Difference
Min 2.900 2.900
Q1 3.025 0.125
Median 3.060 0.035
Q3 3.240 0.180
Max 3.520 0.280
Burn Difference
Min 2.720 2.720
Q1 2.920 0.200
Median 3.080 0.160
Q3 3.200 0.120
Max 3.380 0.180
Normal Boxplot Burn Boxplot
No. Reference (L/F) Burn (L/F)
1 3.20 2.98
2 3.04 2.80
3 3.52 2.72
4 3.04 3.38
5 3.36 3.12
6 3.02 2.98
7 3.04 3.20
8 3.24 3.36
9 2.90 3.32
10 3.24 2.78
11 3.02 3.02
12 3.02 3.00
13 3.30 3.20
14 3.06 3.26
15 3.06 3.04
16 3.04 3.20
17 3.08 3.26
18 3.52 3.20
19 3.44 3.02
20 3.06 3.02
21 2.90 2.90
22 3.08 2.90
23 3.26 3.16
24 2.92 2.88
25 2.94 3.36
26 3.04 2.76
27 2.98 2.72
28 3.28 3.20
29 3.10 3.20
30 3.04 3.14
Mean 3.1247 3.0693
Mode 3.0400 3.2000
Standard 0.1726 0.1980
Raw data
10. Differences of breaking force between
burn mark sample & normal sample
Total model samples is n=30,
Reference sample is μ =3.1247kgF; Burn mark sample is μ =3.0693kgF,
Difference gap: 0.055kgF (1.77%) Small differences.
P value = 0.253338 > 0.05;
Result: Not Significant different between 2 sample mean values.
H0 hypothesis accepted.
Conclusion: The burn mark samples have no significant difference with normal samples
breaking force. Therefore, burn mark is appearance defects but not affected part function.
11. The Request of Concession
1. Part surface is not inspected for cosmetic attributes
and this surface of bottom housing will not explore
after assembly into mother’s body.
2. Burn mark wouldn’t further lead to any functional
issue. Based on breaking test analysis, the burn mark
area P-value is 0.253338 > 0.05 which strengthen is
no significant different from normal samples. The
confident level for the test is 95%.
3. Raw material is expensive and lead time of purchase
new material is more than six months.
4. Mold have improved in Enplas Vietnam and FAI
sample is submitted to Avago for approval.
