Design and Dynamic Control

of a Production Line

Project Team

Aslıgül Börühan

Ayşe Doğan

Ayşe Melis Gökkan

Ceren Yeni

Yazgül Yurğun

Advisors

Murat Fadıloğlu

Sinem Özkan

Company Advisor

Seçkin Menteş

Established in 1978, located in Çiğli

Teknik Balans

Workforce of 80 employees

Industrial balancing machines,

automative service and garage equipments

Symptoms

● Inefficient organization of work space

● Poor layout

● Delays in satisfying customer demand

Problem

● Inefficiency throughout the process

4 different types of wheel balancing machines on the production line

Pull production system with no stock

Assembly Line Balancing (ALB) andProduct Sequencing to

Minimize cost and production time Increase productivity

• Large number of tasks • Long production lead times • High variability between production times

● Insufficient production capacity

Solution Methodology

Heuristic Method TARGET 14 Model 1 products per day

8 working hours – 1 hour¹ = 7 hours

7 hours/14 units= 0.5 hour/unit²

125 min³ 30 min/station= 5 stations

¹Two breaks and a lunch time

²Every 30 minutes a product should be manufactured

³Production time of the fastest model

● Kilbrage- Westers Algorithm is used to assign tasks.

Mathematical Programming Method

● LINGO’s optimal solution, identical to the result of our heuristic

Innovatively using buffer stocks to reduce

the damage due to process time variability in

mixed model lines!

Obtained fromLINGO Software

2x

Mo

de

ls

Cycle Time in Minutes

M4* (Slowest Product) M1* (Fastest Product)

•According to a generated scenario for

showing the usage of buffer stocks

Validation & Verification of the Solution

Parameters:

Model Formulation

N = Total number of tasks in the problem S = Number of stations 𝑃𝑅𝑘 = Subset of all tasks that precede task k, k=1,…,N 𝐷𝑘 = Performance time of task k, k=1,… ,N

𝑉𝑘𝑠 = 1, if task k is assgined to station s

0, otherwise

𝐴𝑘𝑠 = 1, if station s is utilized

0, otherwise

Decision Variables:

𝑠=1

𝑆

𝑉𝑘𝑠 = 1 for 𝑘 = 1 ,… , 𝑁

𝑉𝑘𝑠 ∈ 0 , 1 ; 𝐴𝑠∈ 0 , 1

Min

𝑠=1

𝑆

𝑠 . 𝑉𝑙𝑠 ≤

𝑠=1

𝑆

𝑠. 𝑉𝑘𝑠

𝑘=1

𝑁

𝐷𝑘 . 𝑉𝑘𝑠 ≤ 𝐴𝑠. 𝐶𝑦𝑐𝑙𝑒𝑇𝑖𝑚𝑒 ∀𝑠 = 1, … , 𝑆

∀k=1,..,N; 𝑙 ∈ 𝑃𝑅𝑘

𝑠=1

𝑆

𝐴𝑠

𝑠=1

𝑆

𝑉𝑘𝑠 = 1 for 𝑘 = 1 ,… , 𝑁

𝑉𝑘𝑠 ∈ 0 , 1 ; 𝐴𝑠∈ 0 , 1

Min CycleTime

𝑠=1

𝑆

𝑠 . 𝑉𝑙𝑠 ≤

𝑠=1

𝑆

𝑠. 𝑉𝑘𝑠

𝑘=1

𝑁

𝐷𝑘 . 𝑉𝑘𝑠 ≤ CycleTime ∀𝑠 = 1, … , 𝑆

∀ k = 1,..,N ;𝑙 ∈ 𝑃𝑅𝑘

(1.1)

(1.5)

(1.4)

(1.3)

(1.2)

(2.1)

(2.5)

(2.4)

(2.3)

(2.2)

(1.1) Objective function for solving the ALB Type 1 Problem (minimizing number of workstations)

(2.1) Objective function for solving the ALB Type 2 Problem (minimizing cycle time)

(1.2) & (2.2) Assignment Constraints

(1.3) & (2.3) Precedence Constraints

(1.4) Cycle Time Constraint for a given Cycle Time

(2.4) Cycle Time Constraint for given number of workstations

(1.5) & (2.5) Binary variable values

Bricker D. L. and S. H. Juang (1993), “A Mathematical Programming

Model of the Assembly Line Balancing Problem”

Das S. K, C. Jaturanonda and S. Nanthavanij (2013), “Heuristic

Procedure for the Assembly Line Balancing Problem With Postural Load

Smoothness,” International Journal of Occupational Safety and

Ergonomics 19 ,531–541.

Literature Review

Kilbridge, M. D., & Wester, L. A Heuristic Method of Assembly Line

Balancing. The Journal of Industrial Engineering, 12(4), 292-298, (1961).

Mendes, A.R., Ramos, A.L., Simaria, A.S. and Vilarinho, P.M. (2005).

Combining Heuristic Procedures and Simulation Models for Balancing A PC

Camera Assembly Line, Computers & Industrial Engineering, 49, 413-431.

How did we achieve it?

Capacity of the line is 17

Model 1 products per day

Reducing the wastes [rework, waiting in queues,

lateness, keeping stock, idle time etc.]

Improving processes

Increasing the utilization

Better layout and material flows

Dynamic schedule

Reducing the effects of changeovers

Maximum ThroughputMinimum Cycle Time

Production Time in Old System

Production Time in Improved System

Model 1 230 min 125 min

Model 2 255 min 134 min

Model 3 296 min 153 min

Model 4 386 min 214 min

100120140160180200220240

0 10 20 30

Pro

du

cti

on

Tim

e

Scheduled Products

M4* (Slowest Product) M1* (Fastest Product)

Worker

Utilizations

Worker 1

98%

Worker 2

99%Worker 3

98%

Worker 4

99%Worker 5

87%

Comparison and Quantification of Improvements

85% INCREASE

IN PRODUCTION

CAPACITY!

Applicability of Proposed Approach

Choice of buffer size is justified!

Dynamic controlof the system withstate variables

13PRODUCTS IN A DAY

Decision Support System

has the flexibility of adding a

new model and changing the

operation descriptions

updates itself according to the

new data

gives the daily schedule

enables to see the process

details and recorded errors

creates a database

Design of the Line

Standard Job Description

Forms

Ön etiket yapıştırılır

Etiket

Temizleyici

Sünger

Sünger ile üstünden geçilir Sünger

Ön etiket alanı ölçülürMetre

Kalem

İş Tanımı Sirion Serisi Sabit Balans Makinası Üretim Hattı

Güvenlik Ekipmanları

Operasyon Tanımı Opeasyon Resmi Gerekli

MalzemelerGerekli Araçlar Uyarılar

NOTLAR

Ürün Modeli Sirion Pro-Sİstasyon

Numarası1

Arka uyarı etiket yapıştırılır

Arka uyarı etiketinin altına Mess

Matic etiketi yapıştırılır

Arka etiketler için ölçüm sacı takılrÖlçüm sacı

Etiketler

Etiketler

Etiketler

Etiketler230 V etiketi yapışıtırılır

TEKNİK BALANS STANDART İŞ FORMU

can be used for educationalpurposes

helps standardize tasks