Reduce defect generation in plastic blow molded part

1. Slide number: 1
6σ
Six sigma Green Belt project
PROJECT NO :- 1

2. Slide number: 2
6σ
D
Define
Improve
DEFINE
MEASURE
ANALYZE
CONTROL
Measure
Analyze
Control
IMPROVE

3. Slide number: 3
6σ
Department NPD-PE
BB mentoring project MR. RAM NARYANA
Name of Team Leader SANDEEP KUMAR
YADAV
Team Members MR. RAJEEV (MOLD.)
MR. LUVKUSH (MQC)
MR. ANIL (PE)
MR. RAHUL (DGN.)
Project Sponsor MKL BAWAL
Place the team
photograph here
Define
Team

4. Slide number: 4
6σ
Define - Project planning
Phases Planned Start date Planned
Completion date
Actual start date Actual completion
date
Status
Define 06.02.19 06.02.19 06.02.19 06.02.19 COMPLETE
Measure 07.02.19 22.02.19 12.02.19 24.02.19 COMPLETE
Analyze 23.02.19 31.03.19 25.02.19 10.03.19 COMPLETE
Improve 01.04.19 15.05.19 TO BE
CONT…….
Control 16.05.19 16.06.19 TO BE
CONT…….

5. Slide number: 5
6σ
Define
• Problem Statement
WARPAGE FOUND IN LUGGAGE BOARD
• Impact Score of the project
62 %
• Part number selected for study
L11101-001A1X
• Suspected Scientific reason(s) for the problem
- INTERNAL HEAT EXPENTION (CURING PROCESS)
- MOISTURE
- MFI (MATERIAL FLOW INDEX)
• Current average rejection in ppm for last 4 months
40000 PPM
• Target
2500 PPM
• Process stage(s) where the problem is detected
ASSEMBLY

6. Slide number: 6
6σ
Define
• Annual Savings in Rs. Lakh if the defect is made zero in the part number
selected for doing the study:-
636 PER PIECE PRICE
Per month rejection reduced 200
200 Part * Rs. 636 = 1,27,200/- per month

7. Slide number: 7
6σ
Define
Improve
DEFINE
MEASURE
ANALYZE
CONTROL
Measure
Analyze
Control
IMPROVE

8. Slide number: 8
6σ
Measure
Process Mapping clearly indicating the generating stage and inspection stages
HDPE
+
MIXING
(40% VIRGIN
+ 58% RG +
2% M.B)
INJECTION
M.B
PRE
BLOW
PINCH
OFF
NEEDLE
ENTRY
PARISON
OUT
AIR
BLOWING
AIR
EXHAUST
MOULD
OPENING
PART
DRAWN
MATERIAL
IN ACCUM
- ULATOR
PAST
BLOW
MOULD
CLOSE
COOLING
CURING
BOP PASTING
M/C TRIMMIMG
PL
TRIMMIMG
INSPECTION / FG

9. Slide number: 9
6σ
Measure
• Maximum and Minimum rejection in % for the last 6 months
• Suspected last manufacturing stage where the problem is generated
• MOULDING
Month Rejection %
Maximum rejection DECEMBER 4.97
Minimum rejection FEBURARY 2.70

10. Slide number: 10
6σ
Measure
• If Concentration chart is applicable, conclusions based on the Concentration chart
done on the product
• PAIRED COMPARISON
• PRODUCT PROCESS SEARCH
• VARIBLE SEARCH
• Number of lines/presses/machines used in the suspected last manufacturing
stage creating the problem
– 1
• Number of streams within the equipment
450 SET
• Response
– Attribute

11. Slide number: 11
6σ
Measure
Photograph of part
FRONT VIEW REAR VIEW

12. Slide number: 12
6σ
Measure
Photograph of defect part
GOOD PART
BAD PART

13. Slide number: 13
6σ
2-D DRAFT DIAGRAM
1.- RECIPROCATING SCREW 6.- PRE-HEATER
2.-COMPRESSED AIR 7.- GRINDING MIXING
3.- HOPPER 8.- ACTUATOR HYDRAULIC GENERATOR
4.- GRNULATOR 9.- DRAW PLATE
5.- BARREL 10.- CORE / PUNCH

14. Slide number: 14
6σ

15. Slide number: 15
6σ
Measure
2. Data collection and analysis
to identify the possible causes
for the problem
D
Define
Improve
Measure
Analyze
Control

16. Slide number: 16
6σ
Measure
Process parameter audit findings
Process parameter Standard Observed Conclusion Correction
done
PRE BLOWING DELAY 10 ±2 10 OK NONE
PRE BLOWING TIME 15 ±5 17 OK NONE
PARISON INJECTION TIME 10 ±5 12 OK NONE
MOTOR RPM( FOR
HOMOGENEOUS MIXTURE)
1400 ±100 895 NOT OK CORRECTION
DONE
MOULD CLOSE SPPED 75 75 OK NONE
MOULD POSITION 380/100/10/0 400/100/10/0 OK NONE
INJECTION PRESSURE 55 ±5 58 OK NONE
INJECTION SPEED 65 ±5 68 OK NONE
SHOT SIZE % 65 ± 8 70 OK NONE
DIE GAP % 5 ± 2 4 NOT OK CORRECTION OK
BLOW PRESSURE 6 ±1 6.3 OK NONE
MOOG START DELAY 2 ±1 2 OK NONE
PRE BLOW PRESSURE 2 ±0.5 2.3 OK NONE
Date:27.02.19
Shift: A
Operator: OMENDRA
Machine SIKA 150 LTR
Selected:

17. Slide number: 17
6σ
Measure
Machine and Tool condition audit findings
Machine /Tool Condition Standard Observed Conclusion Correction
done
HEAD TO MOULD GAP 165 MM 165 MM OK NONE
FRONT DISTANCE 225 MM 225 MM OK NONE
BACK DISTANCE 225 MM 225 MM OK NONE
DIE CORE SIZE Ø 600 MM Ø 600 MM OK NONE``
BLOW PIN TYPE NEEDLE BLOW NEEDLE BLOW OK NONE
DIA CORE TYPE DIVERGENT DIVERGENT OK NONE
MOULD DIMENSION 1430/630/1050 1430/630/1050 OK DONE
Date: 27.02.19
Shift: A
Operator: OMENDRA
Machine SIKA 150 LTR
Selected:

18. Slide number: 18
6σ
4.7 4.9
3.7
2.7
0
2
4
6
8
10
NOV. DEC. JAN. FEB.
Rejn %
Monthly rejection trend for the period from NOV. to FEB.
Measure
Double click on the graph to update the graph for your project

19. Slide number: 19
6σ
Measure
Reasons for Abnormal rejections in Monthly analysis
Abnormal
month
Possible reasons Actions taken
NOVEMBER PRE BLOW UNEVEN
WALL THIKNESS NOT UNIFORM
ADDITIONL AIR SUPPLY ADDED
STUCKED MATERIAL REMOVE FROM FROM
DIA CORE
DECEMBER RIB THIKNESS HIGH
HEAT EXTRACT DELAYED
BLOWING EXHAUST DELAY
TOP SEALING EDGE ISSUE
MIXING RATIO CHANGE
BLOWING TIME INCREASE
NEEDLE PIN CHANGED
PINC OFF HUB SETTING CHANGED
JANUARY BLOWING A & B DELAY AIR DROP FOUND, CHANGE PNEUMATIC
ACCESSORIES , NEEDLE PIN CHANGE
FEBURARY TEMPRATURE FLUCTUATION
ACCUMULATRE PUSH OUT
LEKAGE FROM DIE CORE
SSR CHANGED
INJECTION PRESSURE SET
CORE POSITION RESET
REFERENCE TAKEN FROM KAKOTORA SHEET

20. Slide number: 20
6σ
Daily rejection trend for the month of FEBURARY
Measure
0
0.5
1
1.5
2
2.5
3
1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728
Rejn 2.70 %
Double click on the graph to update the graph for your project

21. Slide number: 21
6σ
Machine Pareto using data for the period of FEBURARY
Measure
Double click on the graph to update the graph for your project
TOTAL PROD.:- 11250 NOS.

22. Slide number: 22
6σ
Measure
3. Identification of SSV’s
(Suspected Sources of
variation)
D
Define
Improve
Measure
Analyze
Control

23. Slide number: 23
6σ
Measure
Final list of Suspected Sources of Variation (SSV’s) for the physical
phenomenon of the problem
No. Suspected Sources of Variation (SSV’s) Design SSV or
Variation SSV
Category
1 RAW MATERIAL PROPERTIES VARIATION P.C
2 INTERNAL HEAT EXPANSION VARIATION PPS
3 MOULD TEMP. HIGH VARIATION PPS
4 ABSENCE OF PROPER COOLING VARIATION PPS
5 THICKNESS VARIATION OR UNEVEN PACKING DESIGN VS
6
7
8
9
10
11
12
13

24. Slide number: 24
6σ
Measure
Final list of Suspected Sources of Variation (SSV’s) for the physical
phenomenon of the problem
No. Suspected Sources of Variation (SSV’s) Design SSV or
Variation SSV
Variable/
Attribute
1 RAW MATERIAL PROPERTIES VARIATION VARIABLE
2 INTERNAL HEAT EXPANSION VARIATION ATTRIBUTE
3 MOULD TEMP. HIGH DESIGN VARIABLE
4 ABSENCE OF PROPER COOLING VARIATION VARIABLE
5 MELTING OF RAW MATERIAL DESIGN VARIABLE
6 THICKNESS VARIATION OR UNEVEN PACKING DESIGN VARIABLE
7
8
9
10
11
12
13

25. Slide number: 25
6σ
D
Define
Improve
DEFINE
MEASURE
ANALYZE
CONTROL
Measure
Analyze
Control
IMPROVE

26. Slide number: 26
6σ
Suspected Sources of
Variations (SSV’s) for the
physical phenomenon of the
problem
MOISTURE
DENSITY OF RM
MATERIAL FLOW INDEX
PARISON TIME
REFILL TIME
BLOWING PRESSURE
NOZZLE TEMPRATURE
CYCLE TIME
CURING TIME
INJECTION PRESSURE
BLOWING -2
NEEDLE AIR TIME (BLOWING -2)
PC – Paired Comparison, PPS – Product/Process search, CS – Component search MCS – Modified Component search MVA – Multivari analysis VS –
Variable search, OBS – Observation, ANOVA – Analysis of Variance, RA – Regression Analysis
Phase – 1- Problem Definition (Identifying SSV’s)

27. Slide number: 27
6σ
Phase – 2- Measure and Analyze
Analysis # 1
• Objective:
To study whether the input materials (or) molding process
causing the problem
•Technique/Tool used:
- PAIRED COMPARISON

28. Slide number: 28
6σ
Phase – 2- Measure and Analyze
Suspected Sources of Variation for the Problem
statement (SSV’s) :-
For input materials:
* HDPE (HIGH DENSITY POLYETHYLENE) material properties:
1. Moisture
2. Density
3. MFI

29. Slide number: 29
6σ
Phase – 2- Measure and Analyze
As per data, lowest and highest
no. are in same category , this is
not the cause of problem.
MOISTURE
RESPONSE MOSITURE (%)
GOOD 0.005
GOOD 0.005
GOOD 0.005
BAD 0.007
BAD 0.007
GOOD 0.007
BAD 0.007
BAD 0.009
GOOD 0.01
GOOD 0.01
BAD 0.01
BAD 0.02
BAD 0.02
BAD 0.02
GOOD 0.03
GOOD 0.03
RAW MATERIAL:-
GRADE:- PPC015/RELIANCE/NATURAL/ PE54GB
PARAMETER:- PERCENTAGE (%)
SPEC.:- 0.005-0.04

30. Slide number: 30
6σ
Phase – 2- Measure and Analyze
Phase – 2- Measure and Analyze
As per data, lowest and highest
no. are in same category , this is
not the cause of problem.
DENSITY
RESPONSE DENSITY g/cm3
GOOD 0.954
BAD 0.954
GOOD 0.954
GOOD 0.954
BAD 0.954
GOOD 0.954
GOOD 0.954
BAD 0.954
BAD 0.955
BAD 0.955
BAD 0.956
GOOD 0.956
BAD 0.956
BAD 0.957
GOOD 0.957
GOOD 0.957
RAW MATERIAL:-
GRADE:- PPC015/RELIANCE/NATURAL/ PE54GB
PARAMETER:- G/CM3
SPEC.:- 0.954-0.959

31. Slide number: 31
6σ
Phase – 2- Measure and Analyze
Phase – 2- Measure and Analyze
As per data, lowest and highest
no. are in same category , this is
not the cause of problem.
MATERIAL FLOW INDEX
RESPONSE MFI (g/10min)
BAD 1.0
BAD 1.2
GOOD 1.2
GOOD 1.2
BAD 1.3
GOOD 1.3
GOOD 1.4
BAD 1.4
GOOD 1.4
GOOD 1.5
BAD 1.5
GOOD 1.5
BAD 1.5
GOOD 1.5
BAD 1.6
BAD 1.6
RAW MATERIAL:-
GRADE:- PPC015/RELIANCE/NATURAL/ PE54GB
PARAMETER:- G/10 MIN
SPEC.:- 1.0-1.7

32. Slide number: 32
6σ
Phase – 2- Measure and Analyze
Analysis # 1
• Objective:
To study whether the Input material Properties are causing
the problem
•Conclusion's:
The SSVs related to Input material Properties are not the
cause for the problem

33. Slide number: 33
6σ
Phase – 2- Measure and Analyze
Analysis # 2
• Objective:
To study whether the Variable process parameters are
causing the problem
•Technique/Tool used:
•PRODUCT / PROCESS SEARCH

34. Slide number: 34
6σ
Phase – 2- Measure and Analyze
Suspected Sources of Variation for the Problem statement (SSV’s)
* For Blow Molding Process:-
1. PARISON TIME
2. REFILL TIME
3. BLOWING PRESSURE
4. NOZZLE TEMPRATURE
5. COOLING TIME
6. CYCLE TIME
Analysis # 2

35. Slide number: 35
6σ
Phase – 2- Measure and Analyze
S.No Variable UOM S.No Variable UOM
1 Pre blow pressure Bar 34 Accu. Puch out delay Sec.
2 Loader rotor Mixing Time Sec 35 Pre blow delay - 1 Sec.
3 Regrainding material % 36 Pre blowing time -1 Sec.
4 Parison length mm 37 Pre blow delay - 2 Sec.
5 Injection Pressure Bar 38 Pre blowing time -2 Sec.
6 Injection Speed mm/sec 39 Mould high pressure Sec.
7 Blow pressure Bar 40 Needle delay Sec.
8 Barrel Temperature Z1 C 41 Oil Temperature C
9 Barrel Temperature Z2 C 42 Mold Open Limit mm
10 Barrel Temperature Z3 C 43 Mold Opening Speeds1 mm/sec
11 Barrel Temperature Z4 C 44 Mold Opening Speeds2 mm/sec
12 Barrel Temperature Z5 C 45 Mold Opening Speeds3 mm/sec
13 Barrel Temperature Z6 C 46 Opening Stroke1 mm
14 Barrel Temperature Z7 C 47 Opening Stroke2 mm
15 Barrel Temperature Z8 C 48 Opening Stroke3 mm
16 Barrel Temperature Z9 C 49 Opening Pressure1 Bar
17 Barrel Temperature Z10 C 50 Opening Pressure2 Bar
18 Die Heater C 51 Opening Pressure3 Bar
19 Chiller Temperature C 52 Mold Close Limit mm
20 MTC temprature C 53 Mold Closing Speeds1 mm/sec
21 Blow delay Sec 54 Mold Closing Speeds2 mm/sec
22 Air exhaust Sec 55 Mold Closing Speeds3 mm/sec
23 Top sealing Sec 56 Closing Stroke1 mm
24 Moog start Sec 57 Closing Stroke2 mm
25 Blow pin entry Sec 58 Closing Stroke3 mm
26 Exhaust delay Sec 59 Closing Pressure1 Bar
27 Time Sec 60 Closing Pressure2 Bar
28 Parison Time Sec 61 Closing Pressure3 Bar
29 Refilling Speed RPM 62 Tonnage Tons
30 Back Pressure Bar 63 Mold Temperature C
31 Refilling stroke mm 64 Melt Temperature C
32 Refillin Time Sec 65 Water Temperature C
33 Vaccume On time Sec
BLOW MOULDING MACHINE PARAMETER

36. Slide number: 36
6σ
Phase – 2- Measure and Analyze
PARISON TIME RESPONSE COUNT
WOW 10.2
WOW 10.2
BOB 10.3
WOW 10.3
BOB 10.4
BOB 10.4
WOW 10.6
BOB 10.6
BOB 10.6
WOW 10.6
WOW 10.8
BOB 10.8
Top Count
Total Count
Bottom Count
Conclusion- ELIMINATED
1
REFILL TIME RESPONSE COUNT
WOW 2.013
BOB 2.017
BOB 2.103
WOW 2.124
WOW 2.142
BOB 2.153
BOB 2.155
WOW 2.155
BOB 2.195
BOB 2.197
WOW 2.203
WOW 2.226
Top Count
Total Count
Bottom Count
Conclusion- CANCEL
LOWER &
HIGHER IN
SAME
GROUP
2

37. Slide number: 37
6σ
Phase – 2- Measure and Analyze
BLOWING PRESSURE RESPONSE COUNT
BOB 2.00 1
WOW 2.01
WOW 2.01
BOB 2.01
BOB 2.01
BOB 2.02
BOB 2.02
WOW 2.03
WOW 2.04
BOB 2.04
WOW 2.05
WOW 2.05
1
1.5
2.5
Top Count
Total Count
Bottom Count
Conclusion- NOT CAUSE
1.5
3
NOZZLE TEMP. RESPONSE COUNT
BOB 170
BOB 170
WOW 180
BOB 180
WOW 190
WOW 190
BOB 190
WOW 200
BOB 210
BOB 210
BOB 220
WOW 220
Top Count
Total Count
Bottom Count
Conclusion- ELIMINATED
4

38. Slide number: 38
6σ
Phase – 2- Measure and Analyze
BLOWING RESPONSE COUNT
BOB 105.2
BOB 105.2
BOB 105.4
WOW 105.4
WOW 105.7
BOB 105.9
WOW 106
WOW 106.4
BOB 106.7
WOW 106.7
BOB 106.8
WOW 106.9 1
3
1
4
Top Count
Total Count
Bottom Count
3
Conclusion- NOT CAUSE
5
CYCLE TIME RESPONSE COUNT
WOW 358
WOW 358
BOB 360
BOB 361
BOB 363
WOW 365
WOW 368
BOB 370
WOW 372
BOB 375
WOW 376
BOB 377 1
2
1
3
Top Count
Total Count
Bottom Count
Conclusion- NOT CAUSE
2
6

39. Slide number: 39
6σ
Phase – 2- Measure and Analyze
Analysis # 2
• Objective:
To study whether the Variable process parameters are
causing the problem
•Conclusion's:
The SSVs related to Variable process parameters are not
cause for the problem

40. Slide number: 40
6σ
Phase – 2- Measure and Analyze
Analysis # 3
• Objective:
• To study whether the Design parameters of molding
process causing the problem
•Technique/Tool used:
Variable search

41. Slide number: 41
6σ
Design Parameters identified for Optimization
A–INJECTION PRESSURE
B–MOOG PROFILE (MATERIAL RATIO)
C-NEEDLE AIE FLO(BLOWING-2)

42. Slide number: 42
6σ
No Parameter ( - Setting ) ( + Setting )
A
INJECTION PRESSURE (BAR)
65
60
55
55
50
45
B MOOG PROFILE (% RATIO) (40+60) (30+70)
C BLOWING -2 (SEC.) 105 112
Parameters setting :-

43. Slide number: 43
6σ
Results
(-) setting (+) setting
2.7 0.08
2.3 0.80
2.1 0.09
2.3 0.09
0.60 0.72
Conclusion:
Process optimisation trails 08.03.19
CAUSE CONFIRM
(D/d) ratio 3.3
2.21
Average of Ranges(d)
Median
0.66
Range
Difference between
Medians(D)
Component: YHB LUGGAGE BOARD
II Run
III Run
Runs
I Run

44. Slide number: 44
6σ
Prioritizing the Parameter
No Parameter ( - Setting ) ( + Setting )
A
INJECTION PRESSURE (BAR)
65
60
55
55
50
45
B MOOG PROFILE (% RATIO) (40+60) (30+70)
C BLOWING -2 (SEC.) 105 119

45. Slide number: 45
6σ
Phase – 2- Measure and Analyze
Root cause analysis summary
N
o.
Root causes identified for the
problem
Technique/Tool
used for
pinpointing
Department
responsible for
controlling
Process owner
responsible for
controlling
1 MOOG PROFILE RATIO
INJECTION PRESSURE
BLOWING -2
VC PRODUCTION PE
2
3
4
5
6
7
8
9
10
11
12
13

46. Slide number: 46
6σ
D
Define
Improve
DEFINE
MEASURE
ANALYZE
CONTROL
Measure
Analyze
Control
IMPROVE

47. Slide number: 47
6σ
Phase – 3 - Improve
Validation of the Root cause(s) -
Summary
Tool used: B vs C
Date on which Validation:
Shift on which validation was done:
Are the root causes validated : Yes/No

48. Slide number: 48
6σ
Phase – 3 - Improve
Validation data for Root cause(s)

49. Slide number: 49
6σ
Phase – 3 - Improve
Analysis of Data for Validation
Number of samples used for doing B vs C 3,3 or 6,6
Validation done with Batches/Pieces
If the Validation was done with Batches what
was the batch quantity
Historic rejection level
Total count
Average of B condition
Average of C condition
Amount of Improvement
Sigma of B condition data
K value
K* Sigma of B condition data

50. Slide number: 50
6σ
Phase – 3 – Improve – Actions Summary
No Root cause(s) Actions Planned Planned
Completion date
Resp Actual
completion
date
Status

51. Slide number: 51
6σ

52. Slide number: 52
6σ
Phase – 3 – Improve
Photograph of actions

53. Slide number: 53
6σ
D
Define
Improve
DEFINE
MEASURE
ANALYZE
CONTROL
Measure
Analyze
Control
IMPROVE

54. Slide number: 54
6σ
D
Define
M & A
Measure &
Analyse
I
Improve
C
Control
CONTROL
1. Result verification

55. Slide number: 55
6σ
Daily rejection trend after
Phase – 4- Control (Result Verification)
Month:
Double click on the graph to update the graph for your project
Daily rejection trend before
Month:
Result verification for the problem

56. Slide number: 56
6σ
Defect Pareto after for month
Phase – 4- Control (Result verification)
Double click on the graph to update the graph for your project
Defect Pareto before for month

57. Slide number: 57
6σ
Monthly trend after
Phase – 4- Control (Result Verification)
0
1
2
3
4
5
Apr May June Jul Aug Sep
KPI
Period:
Double click on the graph to update the graph for your project
0
1
2
3
4
5
Oct Nov Dec Jan Feb Mar
KPI
Monthly trend before
Period:
Result verification for the KPI

58. Slide number: 58
6σ
Phase – 4 Control (Result verification)
Projected annual savings before
the start of the project in
Rs. Lakhs:
Actual savings realized now in
Rs. Lakhs:

59. Slide number: 59
6σ
D
Define
M & A
Measure &
Analyse
I
Improve
C
Control
CONTROL
2. Standardization and
Learnings

60. Slide number: 60
6σ
Ongoing monitoring by Black Belt for 6 months for
sustenance of results
Black Belt :-
Mr.Shailendra Rahigude
Problem Statement :-
Size variation in HA Crank Shaft journal
diameter .
(Specs : 69.971 to 69.990 mm)
Part name / number :-
HA4 Crank Shaft , 04.005.09.0.00
Rejection trend – Current Vs. Earlier Actions Monitoring Status
MultiVari analysis
Highest variation in m/c
no 5412
Funneling # 1
Funneling Summary
MultiVari analysis
Funneling # 2
Funneling # 3
Cause(s)
P – P variation highest
due to operator
intervention
Hardware analysis
Wheel slide axis having
taper 0.35 mm.
MultiVari analysis
72
68
11
14
7
2 1
7 5
9
3 6 5
8
1 2 2 5
0 2
0
10
20
30
40
50
60
70
80
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
06
-
07
07
-
08
08
-
09
2007-08 2008-09
Qty.
Before Current
HA Crank Shaft – Journal Dia. minus Between Centers alignment for m/c no. 5412
0.04
0.03
0
0.01
0.02
0.03
0.04
0.05
0.06
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar
2008 - 09
In
mm Specs : 0.05 mm