REDUCE SCRAP Loss OF A PA CEMAKER LEAD
APPL YING LEAN-SIX SIGMA
Orlando Babilonia Ayala
Mani~facturing Engineering
Car/os A. Pons Fontana, Ph.D.
Industrial Engineering Department
Polytechnic University ofPuerto Rico
ABSTRACT what types of electrical pulses to send to the heart
A pacemaker is an electronic device that is and when those pulses are needed. The lead
p/aced under the skin to help control abnormal connects the generator to the heart.
heart rhythms. It consists of a battety, a In a pacemaker leads manufacturing plant, the
computerized generator, and lead (wires) with loss related to scraps from May 2008 to December
electrodes on one end. In a pacemaker leads 2008 was $81,223.92. Sleeve Head Assembly was
manufacturing plant, the loss related to scraps from identified as the loss higher generator related to
May 2008 to December 2008 was $81,223.92. scraps with a total loss of $49,765 representing a
Sleeve Head Assembly was identified as the loss 61% of the total scrap loss. The major cause for the
higher generator related to scraps with a total loss Sleeve Head Assembly scraps is related to leakage
of $49, 765 representing a 61% of the total scrap at the sleeve head joint.
loss. Appling DMAIC methodology from Lean Six- The objective of this research was to improve
Sigma, the possible causes and action were the pacemaker lead manufacturing process to avoid
evaluated. The major cause for the Sleeve Head leakage at the Sleeve Head Sub-assembly and
Assembly scraps is related to leakage at the sleeve reduce loss related with scrap. With an efficient
head joint. DOE (Design of Experiments,) was use manufacturing process, variability was reduced and
to optimize distal & proximal Sleeve Head more leads comply with the acceptance criteria.
Bonding. A factorial experiment 2” (for k ≥ 3 Less worked material were loss as scrap. Cycle
Factors) was run to determine the significant time of product was reduced. Manufacturing
factors. The experiment results appoint to prhne process will be leaned. The total manufacturing
with adhesive tab 5, use adhesive Tab 5 for the cost will decreased.
360° and one (1) grove layer. A change on DMAIC methodology from Lean Six-Sigma
mani~acturing process was implemented on April was use to study an existing pacemaker lead
07, 2009 to i-educe leakage defect at the sleeve manufacturing process that was not performing
headjoint. adequately. The possible causes and action were
evaluated to improve the manufacturing process to
PROBLEM STA TEMENT reduce leakage defect at the sleeve head joint.
A pacemaker is an electronic device that is The research demonstrated the benefit of Lean
placed under the skin of the chest or abdomen to Six-Sigma to improve the manufacturing process.
help control abnormal heart rhythms. It consists of The process is leaned. Defect waste and the
a battery, a computerized generator, and lead (wire) financial loss was decrease. Cardiologists are
with electrodes on one end. The battery powers the supplied with the pacemaker leads on time to avoid
generator, and a thin metal box surrounds it and the delay in the implantation surgery. The patient
generator. A computerized generator figures out (final customer) will be provided with a quality
Abril 2010 Revista FoliTechné /
pacemaker. Lead will remain being manufacturing in the wires that detect the movement, blood
in the site. temperature, breathing, or other factors that indicate
The pacemaker is the only opportunity for life the level of physical activity. The leads in the
for some people with heart disease. The pacemaker pacemaker send electrical pulses to and from the
leads has to be deliver to the patients when they heart and the generator. Pacemakers have one (1) to
need it without any defect. three (3) leads that are placed in different chambers
LITERATURE REVIEW of the heart. [6]
A pacemaker is use to help control abnormal LEAN Six-SIGMA
heart rhythms. The intention of the research was to The goal of any business is to produce the
reduce loss related with scraps in a pacemaker leads highest quality product or service in the shorter lead
manufacturing plant applying Lean Six-Sigma. A time possible with the least amount of resource
literature review was performed to provide to the investment delivered to the customer at the lowest
research the required background. possible cost. Lean Manufacturing seeks to
PACEMAKER improve flow in the value stream and eliminate
waste. Lean methods typically target seven types
A normal heartbeat is created by an electrical of waste; defects, wait time, over-production,
impulse that is generated within a specialized area transportation, motion, inventory and processing.
of the heart and travel down specific pathways to By eliminating waste, manufacturers can do more
stimulate the cardiac muscle to contract. If any part with less; capital equipment, floor space, operator
of the conduction system is dysfunctional for some effort, direct and indirect labor, and inventory.
reason, the normal heartbeat may become too slow Lean Manufacturing systems are designed to be
(l3radycardia) or fast (Tachycardia). These are clearer, safer, better organized, produce better
abnormal heart rhythms or arrhythmias and in some quality and he more productive [2].
cases, physicians will recommend implantation of a Six Sigma is a business management strategy that
pacemaker to correct it [4]. emphasizes the improvement of process for the
Pacemakers are electronic devices that are purpose of reduction variability and making general
placed under the skin of the chest or abdomen to improvement. It seeks to identifij and remove the
help control abnormal heart rhythms. The causes of defects and errors in a process using a set of
pacemaker’s generator sends electrical pulses that quality management methods including statistic [1].
may stimulate the upper chambers of the heart Six Sigma uses a powerful framework knowing
(atria), lower chambers (ventricles) or both. These as DMAIC, a system that brings measurable and
signals make the heart contract in a more regular significant improvement to existing processes that
rhythm than the chamber would otherwise to are falling below specifications. DMAIC is an
prompt the heart rhythm to beat at a normal rate [5]. acronym for five interconnected phases: Define,
A pacemaker consists of a battery, a Measure, Analyze, Improve and Control.
computerized generator, and lead (wires) with In the Define phase, the project team identifies
electrodes on one end. The battery powers the a project for improvement based on business
generator, and a thin metal box surrounds it and the objectives and the needs and requirements of the
generator. A computer chip figures out what types customers. In the Measure phase, the team begins
of electrical pulses to send to the heart and when with the proper metrics to evaluate the success of
those pulses are needed. The lead connects the the project. The initial capability and stability of
generator to the heart. The computer chip uses the the project is determined in order to establish a
information it receives from the leads connected to measurement baseline. Valid and reliable metrics to
the heart. It also may use information from sensors monitor the progress of the project are established
8 Reci’aa Foh7’ec’hné Abril 2010
during the Measure phase; input, process and METHODOLOGY
output indicators are identified. Through the DMAIC methodology was used to determine
Analyze phase, the team can determine the causes the causes of defect to improve the process and
of the problem that needs improvement and how to comply with specifications. It consisted in
eliminate the gap between existing performance determining the current manufacturing process
and the desired level of performance. This involves conditions and provides improvements to reduce
identi& identi~ing the key variables that are most scraps loss.
likely to create process variation and defects. The
Improve phase is where the process transitions into DEFINE
solutions. Critical inputs have been verified and The loss related to scraps from May 2008 to
optimized toward nailing down the problem causes. December 2008 in a pacemaker leads (wire)
Once problem causes are determined in the Analyze manufacturing plant was $81,223.92. Table 1
phase, the team finds, evaluates through testing, shows the pace maker lead scrap per component
and selects creative new improvement solutions. (item) identified by letters from A to K, Item B
Success in the Control phase depends upon how was identified with the higher amount of scrap with
well the team did in the previous four phases. a 61% of total scrap following by Item F with a
Solutions are now implemented and tools are put in 22% of total scrap. However, monetary loss was
place to ensure that the key variables remain within higher for item F with a total loss of $49,765
the acceptable ranges over time so that process representing a 61% of the total scrap loss.
improvement gains are maintained. The team
develops a project hand off process, reaction plans, Table 1: Pace Maker Lead Scrap per Component
and training materials to guarantee performance and
I otal Percentage Percentage
long-term project savings. Documenting the project Item Piece of Total Scrap Cost of Total
is very important so that the new procedures and Scrap Scrap Scrap Cost
lessons learned are maintained and provide concrete A 3 0.15% $ 2.75 0.00%
B 1,257 60.84% S 3,396.79 4.18%
examples for the organization [3].
C 110 5.32% $ 2,093.66 2.58%
DOE (Design of Experiments) is a systematic D 5 0.24% $ 54.71 0.07%
approach to investigation of a system or process. It 5 32 1.55% $ 1,222.43 1.51%
is a structured, organized method that is used to F 450 21.78% S 49,764.96 61.27%
determine the relationship between the different G 3 0.15% S 336.74 0.41%
factors (Xs) affecting a process and the output of H 2 0.10% S 238.97 0.29%
1 106 5.13% $12,388.56 15.25%
that process (Y). A series of structured tests are
J 83 4.02% 59,837.92 12,11%
designed in which planned changes are made to the K 15 0.73% $1,886.43 2.32%
input variables of a process or system. The effects Total 2,066.00 units S 81,223.92
of these changes on a pre-defined output are then
assessed. Refers to experimental methods used to The item F (Sleeve Head Assembly) had been
quantif5’ indeterminate measurements of factors and selected for the research to reduce the scrap loss.
interactions between factors statistically through Figure 1 illustrates a Sleeve Head Assembly
observance of forced changes made methodically as Diagram. The defects found in the Sleeve Head
directed by mathematically systematic tables [1]. Assembly were evaluated and the major of scraps is
A combination Lean Manufacturing and Six related to leakage. Refer to Table 2. Sleeve Head
Sigma (Lean Six Sigma) provides a structured leakage occurred at the joint where the two (2)
improvement approach and effective tools to solve Sleeve Head Subassemblies (Proximal and Distal)
problems. This creates rapid transformational are connected. The leakage causes non-compliance
improvement at lower cost. in the pace/sense inter-circuit bOy dielectric test
A/nil 2010 Resist;, PollTechnd 9
and in the pace/sense inter-circuit impedance test. sleeve head is filled with urethane adhesive (Tab 6)
The pace/sense inter-circuit on the lead does not and the sleeve heads are slide together maintaining
meet dielectric test requirements for finished leads their orientation. The joint are place in a dry box
tested. for 15 minutes. Refer to Figure 4.
Proximal Subassembly Distal Subassembly
Figure 1: Sleeve Head Assembly
Table 2: Sleeve Head Assembly Defects
QTY Leak 0G With LeakMonth
Defect Defect Defect from Total
Defect Figure 2: Gap in the Distal Sleeve Head
Aug-08 86 67 78%
Sep-08 358 III 31%
Oct-08 175 122 70%
Nov-08 76 49 64%
Dec-08 148 32 22%
Jan-09 52 38 73%
Total 895 419 47%
The lead Manufacturing Process was reviewed. Figure 3: Proximal Sleeve Head Assembly
The Sleeve Head Assembly is built into the lead at Operation
the beginning of the manufacturing process. The
causes for the leakage were during the seal process
of the gap between the distal and proximal Sleeve B- S
Head subassemblies on the Sleeve Head sub
assembly operations. A significant area of concern
was the groove on the proximal Sleeve Head and Figure 4: Distal Sleeve Head Assembly Operation
the gap that existed when the part was made to the
distal Sleeve Head. Refer to Figure 2. MEASURE
During the Proximal Sleeve Head Assembly Three (3) functional tests are performed to the
operation, the electrode ring is assembled into to leads: Leak Test, Impedance Test and Dielectric
the proximal sleeve head assembly. The tubing Test. All leads (I000o) are tested as part of the
band is positioned over electrode ring and threaded manufacturing process. The leakage at the Sleeve
portion of sleeve head. Urethane adhesive (Tab 6) Head creates an ionic bridge decreasing the
is applied in the distal slot of the sleeve head and let resistance. It causes non-compliance in the
dry for 5 minute in a dry box. Refer to Figure 3. pace/sense inter-circuit impedance test and
On the Distal Sleeve Head Assembly operation, the dielectric test.
distal sleeve head assembly is threaded onto the For the qualification process, 32 lead will be
helix, rotate until distal sleeve head assembly and submitted to the three (3) tests. Refer to equation
proximal sleeve head are close to each other. The (I) for test 2 and 3.
10 Ret ista I’obTechné Abn] 2010
• Test 1: Leak Test (4.0 psi) the cube. Refer to Figure 6 for the 2 Design and
• Test 2: Impedance Test (R 5Okfl) Table 3 for the 2~ design matrix.
• Test 3: Dielectric Test (I < 2mA)
V Ix R(Example: bOy 2mA x 50k ohms) (I)
ANAL YZE
An impedance distribution was calculated to
evaluate the impedance variability. The results on
the impedance test do not follow a uniform
distribution, obtaining values out of specifications.
Refer to Figure 5.
Figure 6: The 2~ Design
Avar In~.dnce
——
•4~~ ‘UI
.‘y_. IL
b~ Table 3: The 2~ Design Matrix._ %S1n.. mgyd- Ifl~I.I,~4K,~ Run A B cN I’m—Is—N —M~ .IJg,~ q..d. as,~ 2 + -
— ._
s~ b~IdbIINg 3 . + -
I — —=—-- I %~ c‘s.M’—wn 1s bM.Ss 4 + + -
an’ •j’m
% 0d. S - - +Is..M b~’
n_c__a —N.— Nh•l IlL 6 + - +
7 - + +
8 + + +
Figure 5: Impedance Distribution
The factors in the experiment were:
The cause of non-conformities in thc lead • A-Primer (Tab 5)
leakage test was the lack of process steps to seal the
• 8-360° Adhesive
gap between the distal and proximal Sleeve Head
• C-Layers in Grove
assemblies. Likely suspect were prime on part,
360° adhesive type (Tab 5 or 6), dry time, number The experiment results appoint to prime with
of groove layers and piece alignment and handling. adhesive tab 5, use adhesive Tab 5 for the 360° and
The immediate decisions were cleaning parts with one (I) grove layer. Refer to Figure 7. In addition,
1-leptane, add a thick coat of adhesive and use the experiment showed that the combination of the
adhesive Tab 6 in grove. The factors to optimize three (3) factors have significant effect in the
were to prime parts with adhesive tab 5, the 360° response. Refer to Figure 8, Figure 9 and Figure
adhesive type (Tab 5 or Tab 6) and number of 10.
groove layers. A new procedure was developed with the
information obtained in the DOE. During the new
IMPROVE
Proximal Sleeve Head Assembly operation, the
DOE (Design of Experiments) was use to electrode ring is assembled to onto the proximal
optimize distal & proximal Sleeve Head Bonding. sleeve head assembly. The tubing band is
A factorial experiment 2I~ (for k > 3 Factors) was positioned over electrode ring and threaded portion
run to determine the significant factors. This study of sleeve head. Refer to Figurell. During the
included 3 factors, therefore, design was a 2~ new operation, Heptane Cleaning and Priming,
factorial design and it had eight (8) runs or proximal sleeve head distal to ring outside is
treatment combinations. Geometrically, the design cleaned with heptane, using a swab. Adhesive-
is a cube with the eight runs forming the corners of Polyurethane Tab 5 is applied on proximal sleeve
Abril 2010 Revista PoliTechné Ii
head 3600 (including the groove) entire surface Main Effects Plot (data means)
distal to ring. Refer to Figure 12. In addition, the P,Trer (lab 5) ~O Adsom
52
Fill Proximal Sleeve Head Groove operation was IS
added. In this operation, urethane adhesive Tab 6 is 4.4
applied in the distal groove of the proximal sleeve 4.0
NO Ye
head and filled 360° around distal face of the _______________________ Tabs TaboUveon&oo,, I
5.2
electrode ring. Refer to Figure 13. On the new
45
Distal Sleeve Head Assembly operation, the distal
4.4
sleeve head assembly is threaded onto the helix, N
4,0
rotate until distal sleeve head assembly and
proximal sleeve head are close to each other. A Figure 9: Factors with Sign jfkant Effect in the
small bead of adhesive Tab 5 is applied to the Response (C)
inside of distal sleeve head. The sleeve heads are
slide together maintaining their orientation. The
joint are place in a dry box for 15 minutes. Refer to
Figure 14.
Cube Plot (data means)
Tabs Figure 10: Factors with Significant Effect in the
Response (13)
Tab S
Primer (Tabs)
Figure 11: New Proximal Sleeve Head Assembly
Figure 7: Factors with SignWcant Effect in the
Response (A) Operation
Preto Qia~t of the Stw,da-dized Effects
Aa=.09
2.09~3
~ 7’ 7’ Sa rth9
ABC / C bys~~asn Figure 12: Heptane Cleaning and Priming
Operation
c~H3>~
~
A ~ H
B
0.0 0,5 1.0 1.5 20 —
sta.dsnlzed effect
Figure 8: Factors with Sign Wcant Effect in the Figure 13: Fill Proximal Sleeve Head Groove
Response (B) Operation
12 Revista PollTechne Abril 2010
reduced and more leads comply with the acceptance
criteria. Less worked material is loss as scrap.
REFERENCES
Figure 14: New Distal Sleeve Head Assembly [1] Breyfogle Ill, Forrest W. Implementing Six
Operation Sigma. Second Edition. New Jersey: John
Wiley & Songs, 2003.
CONTROL
[2] Hobbs, Dennis P. Lean Manufacturing
Standard Operating Procedures (SOPS) were Implementation. First Edition. USA: J.
updated. Three (3) additional operations were Rosshing, 2004.
added to the Sleeve Head Sub Assembly process.
Personnel were trained in the procedures changes [3] Ming-Hsien Caleb Li, and Abbas Al-Refaie..
and were certified in the operations. “Improving wooden parts quality by adopting
DMAIC procedure.” Quality & Reliability
CONCLUSION Engineering International 24.3 (Apr. 2008):
35 1-360. Academic Search Complete. EBSCO.
Appling DMAIC methodology from Lean Six-
18 Oct. 2008
Sigma, the causes of scrap and action were
evaluated. The assembly that generated more scrap [4] www.medicinenet.com pacemaker article.htm
was the sleeve head due to leakage at the joint.
[5] www.nhlbi.nih.gov/health/dci/Diseases/pace
DOE (Design of Experiments) was use to optimize pace whatis.html
distal & proximal Sleeve Head Bonding. A
factorial experiment 2 was run to determine the [6] www.yourtotalhcalth.iviIlage.com
significant factors. Factor evaluated were Primer pacemaker.html
(Tab 5), 3600 adhesive (Tab 5 or Tab 6) and layers
in Grove. The experiment results appoint to prime
with adhesive tab 5, use adhesive Tab 5 for the
3600 and one (1) grove layer. In addition, the Orlando Babilonia se gradud
experiment showed that the combination of the del programa de MaestrIa en
three (3) factors have significant effect in the Ingenieria de Manufactura,
response. A new procedure was development with en la colaciOn de grados de
the information obtained in the DOE. Personnel 2009. El señor Babilonia
were trained in the procedures changes and were posee tin grado de
certified in the operations. bachillerato en IngenierIa
The research improves the manufacturing MecOnica y sus intereses en investigacidn van
process of a pacemaker lead. Variability was alineados al area de Gerencia de C’alidad.
Abril 2010 Ikiicta Pill 13