Quality Control on Flour Rice with Statistical Quality Control (SQC)

Method and Taguchi Method

Nurhayati Sembiring

, Elisabeth Ginting

and Sudikse Inggrid

Department of Industrial Engineering, Faculty of Engineering, Universitas Sumatera Utara , Jl. Almamater Campus

Universitas Sumatera Utara, Medan 20155

Keywords: Statistical Quality Control, Taguchi Method, Optimum, Quality Control, Method.

Abstract: This research was conducted on manufacturing companies engaged in the food industry. The production

process in the company applies the make to stock system. It produces rice flour dan sticky rice flour. Rice

flour is the most popular according to the market. Many defective products that arise during the flour

production process are due to product quality not meeting company standards. The company's daily rice

flour target can be reduced due to the high number of defective products produced. Company standard

determines the quality of rice flour where the product does not meet the perceived quality is not good. The

purpose of this research is to control the quality of rice flour and reduce the number of defects in rice flour.

Taguchi method is one methods that can be used to make improvements. The results of the Taguchi method

show that the optimum level of ash defects of more than 1% is 192 rpm milling spindle speed, 2.5 hours

of rice immersion duration and 197 ° C temperature. Optimum level for crude fiber defects consists of

spindle speed of milling machine is 179 rpm , the duration of soaking rice is 2.5 hours and the counting

process for 1 hour. Application of the Taguchi method, the amount of rice flour that is not suitable also

decreases because ash content reduces the average defect from 5.3 kg / day to 4.89 kg and for crude fiber

from 5kg / day to 4.61 kg.

1 INTRODUCTION

Statistical Quality Control (SQC) and Taguchi

method have been recognized as an effective

approach to process monitoring and diagnosis to

control the quality characteristics of methods,

machines, products, equipment for both companies

and operators (Srinivasan, 2011).

Statistical quality control (SQC) is divided into

product and process control. The quality of the

product can be control through the product and

process control in any manufacturing industry and the

product control has to perform when the product is in

finished mode.

Product control is a technique that is just as

important as process control in the field of statistical

quality control to maintain product quality. However,

in product control, sampling plan for attributes and

variables are available but sampling plan for attribute

is easy to perform in any industry or manufacturing

unit (Kumar, 2018).

Taguchi uses the delineation of experiments to

determine an ideal configuration for the parameters of

the process, as well as, to analyze the existing

interactions between the controllable factors (Souza,

2018).

SPC is an optimization philosophy concerned

with continuous process improvements, using a

collection of (statistical) tools for data and process

analysis making inferences about process behavior

(Chede, 2016).

The process of producing rice flour consists of

eight work stations namely, the outpouring, storage,

washing, grated, refinement, drying, filtering and

packaging. In many companies there is rice flour

whose quality does not meet company quality

standards.

Disability that occurs in rice flour is moisture

content of more than 1%, fiber is still rough and ash

content more than 1%. During the period January

2016 to January 2017 has an average of 22.72% /

month, so the company needs to do the control quality

so that the future will not harm the company either

materially or non-material.

Research focuses on the quality of rice flour to

reduce the number of rejects in the company. The

Sembiring, N., Ginting, E. and Ingrid, S.

Quality Control on Flour Rice with Statistical Quality Control (SQC) Method and Taguchi Method.

DOI: 10.5220/0010084402670272

In Proceedings of the International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches (ICOSTEERR 2018) - Research in Industry 4.0, pages

267-272

ISBN: 978-989-758-449-7

267

research was conducted quality control by using

statistical quality control (sic) method and Taguchi

method.

The result of this research is to know the number

of rejects that accumulate on the production floor and

to know the main cause of the rejects. And if

occurred, a plan must be devised to improve the

production then that plan must be put into action

(Qasim, 2014).

2 RESEARCH METHODS

The type of research is a type of experimental

research, i.e. which is a study that aims to investigate

the causal relationship and how many relationships

are by imposing treatment on one or more

experimental groups and comparing the results with

one or more control groups or groups that are not

subject to treatment (Paradis, 2016).

The results of this study are expected to minimize

defects in rice flour products. The object of research

observed is rice flour, which is about the quality of

rice flour that does not meet the specification or

standard and categorized a defect product.

Data collection methods used in this study are

through direct observation and interviews with

companies (Johnston, 2014). The Data processing

methods used in this study is (Besterfield, 1998):

1. Identification of factors that cause the deviation of

rice flour quality,

2. Determination of the number of levels and factor

level values for the accuracy of the experiment

3. Calculating the number of degrees of freedom, to

know how many minimum experiments

performed.

4. Selection of appropriate orthogonal matrices

depended on the value of factor and expected

interaction and the level value of each factor.

5. Implementation the Taguchi Method

This research stage can be explained briefly through

block diagrams. The Block diagram of this research

can be seen in Figure 1.

Goal Setting

Data collect ion

Primary Data

-Interviews

- Rice Data

Data processing

-SQC

-Taguchi

Problem Solving Analysis

Conclusions and recommendations

Problem Formulation

Secondary Data

- Product Defects Data

- Company History

- A general description of the

company

Problem Identification

Figure 1. Block Diagram of Research.

3 RESULTS AND DISCUSSION

3.1 Quality Control Tools

The Method used to maintain standards in

manufacturing products is by testing sample from

output to specification (

Neuburger, 2017). This quality

control tool is in charge of controlling the quality of

statistical to find out the quality data of rice flour that

is still within the control limits. The results of the

quality control tools produced are as follows:

1. Map Control

Control charts are used to see if the proportion of

ash defects in homogenized rice flour or not

(Blitzkow,2013). In this study map, c is used

because the disability that occurs in rice flour is in

the form of attribute data (Ahme, 2011). The result

of the control chart on the type of ash disability (>

1%) and fiber are still rough is that all data is in

control.

2. The Cause and Effect Diagram

This diagram is used to determine the causes of

rice flour in detail (Liliana, 2016). The result of

causes and effect diagrams for ash disability are

some factors causing disability such as human

factors, machinery, methods, materials and

environment (Belouafa, 2017). And the main

factor is the speed the rotary grinding machine,

drying temperature and long immersion of rice.

The cause and effect diagram for fiber defects is

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

268

still rough due to several factors such as humans,

machine, materials, and methods. The main factors

that cause are the speed of rotary grinding

machine, the process of dissolution and the long

immersion of rice.

3.2 Identification of Causes of Rice

Quality Diversity

The cause of rice quality drift irregularities can be

seen in the following figure 2.

Ash Content (>1%)

The quality of rice is not good

Lacking to keep working

environment clean

Not filtered on flour

machine all over the dust

and other debris

Rolling speed of the grinding

machine is too fast

Maintenance is not good

Not Thorough While

Working

Working Environment is dirty

Cleanliness of storage tanks

Rice immersion duration

Drying Temperature

Figure 2. Diagram of cause as a result of Ash Content (>

1%).

Figure 2 shows that the cause of ash disability (> 1%)

is the human, machine, method, environment, and

material factor.

Based on the results of the way with that the main

factor is the machine, namely the rotational speed of

the milling machine, the duration of rice immersion

and the drying temperature. For the factors causing

irregularities in the fiber is still rough can be seen in

Figure 3.

Fiber Still Rough

Characteristics of different rice

Less experienced

Immediate rice immersion

time

Maintenance is not good

Not Thorough While

Working

There is rice that is not

completely dissolve d by a

scar

The process of dissolution is

too fast

Rolling speed of the grinding

machine is too fast

Figure 3. Diagram of Causes of Fiber Still Rough.

Figure 3 shows that the cause of fiber defects is still

rough is the human factor, machine, method, and

material.

Based on the results of the interview with the

company that the main factor is the machine, the

rotational speed of the milling machine, the duration

of rice immersion and the dissolution process.

3.3 Determining the Number of Levels

and Level Values

Determining the number of important levels means

for the accuracy of the experimental results (Lamont,

2015). The more levels that are studied the

experimental results will be more researched because

the data obtained more. Determination of this level is

done on the following considerations:

1. The value of each level is within the range set by

the company.

2. Point levels are indicating extreme values.

3. The level can still be handled by the existing

process technology.

Level determination for ash content (>1%) can be

seen in Table 1. The level determination for fiber is

still rough can be seen in Table 2.

Table 1. Determining the Number of Levels and Ash Levels

(> 1%).

Num Control Factor

Level

Machine Play Speed

Milling

179

rpm

192

rpm

B Old Immersion of Rice

hours

2,5

hours

The process of

dissolution

187

C 197

Quality Control on Flour Rice with Statistical Quality Control (SQC) Method and Taguchi Method

269

Table 2. Determination of Number Level and Fiber Level

Levels Still Rough.

Num Control Factor

Level

Machine Play

Speed Milling

179

rpm

192

rpm

Old Immersion

of Rice

hours

2,5

hours

The process of

dissolution

hours

3.4 Calculation of the Number of

Degrees of Freedom

The calculation of degrees of freedom is done to

calculate the minimum amount of research that must

be done to investigate the observed factors

(

Krishankant, 2012).

The computation of degrees of freedom and the

proposed combination will later affect the selection in

the orthogonal matrix table.

V = Number of Levels – 1

In this study, the degrees of freedom for each

type of disability is the same:

1. Factor A = 2 levels

2. Factor B = 2 levels

3. Factor C = 2 levels

Calculation of degrees of freedom can be seen in

Table 3.

Table 3. Calculation of Degrees of Freedom.

Control

Factor

Degrees Free (DB) Total

A 2-1 1

B 2-1 1

C 2-1 1

TOTAL 3

3.5 Selection of Orthogonal Matrices

In selecting an appropriate orthogonal matrix, an

equation of orthogonal matrices is required which

presents the number of factors, the number of levels

and the number of observations made. The general

form of the orthogonal matrix is La (bc).

The orthogonal matrix used in this study was L8

(23). The arrangement of

orthogonal matrix L8

(23) can be seen in Table 4.

Table 4. Orthogonal Array Matrices.

Experiments

Column / Factor

1 2 3

1 1 1 1

2 1 1 2

3 1 2 1

4 1 2 2

5 2 1 1

6 2 1 2

7 2 2 1

8 2 2 2

3.6 Implementation of Taguchi Method

The Taguchi method is used to investigate the

interaction between factor and factor level in the

quality of rice flour. Characteristics used are smaller

the better (Cheng, 2016

Calculation of confirmatory experiments using

factor and factor level that has been determined to

produce optimal condition and done as many as 6

times experiment by calculating the average value of

flour and the variability of rice flour. (Amirul 2016)

The results of the Taguchi experiment can be seen in

Table 4

ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramiﬁcation Researches

270

Table 4. Optimal Level Result of Taguchi Experiment.

Ash Content (>1%)

Factor

Percent

Contributio

n (%)

Optimu

m Level

Value of

Optimum

Level

Rotating

Speed of

Milling

Machine

(A)

36,30 2 192 rpm

Lama Old

Immersion

of Rice (B)

- 2 2,5 jam

Drying

Temperatu

re (C)

11,85 2 197

Fiber Still Rough

Factor

Percent

Contribution

(%)

Optimum

Level

Value of

Optimum

Level

Rotating

Speed of

Milling

Machine (A)

- 1 179 rpm

Lama Old

Immersion

of Rice (B)

16,17 2 2,5 jam

Drying

Temperatur

e (C)

26,73 1 1 jam

The interpretation results for the calculation of the

amount of flour defect can be seen in Table 5.

Table 5. Interpretation Result of Calculation of Total Flour.

Response (Afkir

Flour Rice)

Predic

tion

Optimization

Type of Disability Ash Level (> 1%)

Experim

ents

Taguchi

Average

(µ)

5,08 4,48 ≤ µ

prediction

≤

5,68

Variabil

ity

(SNR)

-13,78 -14,38 ≤ µ

prediction

≤ -13,18

Average

(µ)

4,89 4,16 ≤ µ

confirmation

≤ 5,62

Confirm

ation

Experi

Ment

Variabil

ity

(SNR)

-13,84 -14,57 ≤

confirmation

≤ -8,22

Types of Fiber Defects Still Rough

Experim

ents

Taguchi

Average

(µ)

4,67 4,90 ≤ µ

prediction

≤

5,26

Variabil

ity

(SNR)

-12,85 -13,35 ≤ µ

prediction

≤ -12,35

Confirm

ation

Experi

Ment

Average

(µ)

4,61 3,86 ≤ µ

confirmation

≤ 5,36

Variabil

ity

(SNR)

-13,67 -14,27 ≤

confirmation

≤ -

12,77

The result of experiment from table above can

be seen that by Taguchi method (Mitreva, 2016) to

confirmation experiment decrease at mean value (μ)

flour of defect rice and decrease of defect variation

that happened compared to average value of defect

of rice flour per day, where for type disability ash

content (> 1%) suffered a defect per day of 5.33kg /

day, after the experiment Taguchi decreased to 5.08

and through confirmation experiments of 4.89. The

same is true for fiber defects still rough, where the

average defect per day is 5kg / day. After the

experiment Taguchi decreased to 4.67, and through

confirmation experiments of 4.61.

4 CONCLUSION

Based on the research that has been done, the

following conclusions are obtained:

1. The cause of the number of reed rice flour to the

type of disability ash content, the cause effect

diagram caused by the terms of machine, material,

human, method and environment, with the main

factor is the rotational speed of grinding machine,

rice immersion duration and drying temperature

Cause the number of reed rice flour the type

defect is still rough, the cause effect diagram is

caused in terms of machine, material, human and

method, with the main cause is the process of

dissolution, the speed of rotary grinding machine

and the duration of rice immersion.

Quality Control on Flour Rice with Statistical Quality Control (SQC) Method and Taguchi Method

271

2. After the Taguchi experiment and confirmation

experiment, it can be seen that the average number

of rejects decreased after the Taguchi experiment

and the confirmation experiment.

3. Combination of optimum factor level which has

significant influence with Taguchi experimental

design as the basis of quality improvement of rice

flour on ash disability type is Rolling Speed of 192

rpm Milling Machine, 2.5 hours Rice Soaking,

2.57C Drying Time and Temperature. The

combination of optimum factor level which the

significant effect on fiber type of defect is still

rough is Rolling Speed of 192 rpm Milling

Machine, 2.5 Hours Soaking Rice, and Drying

Temperature 197oC. Rotary Speed of Grinding

Machine 179 rpm, Length of Immersion of Rice

2.5 hours, and 1- hour Dissolution Process.

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