Process Control in Textile Manufacturing

Abhijit Majumdar, Apurba Das, R Alagirusamy, V K Kothari

• Publisher: Woodhead Publishing
• Year: 2012
• Print ISBN: 9780857090270
• eBook ISBN: 9780857095633
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Complex raw materials and manufacturing processes mean the textile industry is particularly dependent on good process control to produce high and consistent product quality. Monitoring and controlling process variables during the textile manufacturing process also minimises waste, costs and environmental impact. Process control in textile manufacturing provides an important overview of the fundamentals and applications of process control methods.Part one introduces key issues associated with process control and principles of control systems in textile manufacturing. Testing and statistical quality control are also discussed before part two goes on to consider control in fibre production and yarn manufacture. Chapters review process and quality control in natural and synthetic textile fibre cultivation, blowroom, carding, drawing and combing. Process control in ring and rotor spinning and maintenance of yarn spinning machines are also discussed. Finally part three explores process control in the manufacture of knitted, woven, nonwoven textiles and colouration and finishing, with a final discussion of process control in apparel manufacturing.With its distinguished editors and international team of expert contributors, Process control in textile manufacturing is an essential guide for textile engineers and manufacturers involved in the processing of textiles, as well as academic researchers in this field.- Provides an important overview of the fundamentals and applications of process control methods- Discusses key issues associated with process control and principles of control systems in textile manufacturing, before addressing testing and statistical quality control- Explores process control in the manufacture of knitted, woven, nonwoven textiles and colouration and finishing, with a discussion on process control in apparel manufacturing

Part I

General issues

1

Basics of process control in textile manufacturing

Vedpal

V. Jain, Indian Institute of Technology Delhi, India

Abstract:

New technologies are constantly being developed and the service life of products is becoming shorter due to changes in customer taste. Statistical process control (SPC) methods for short production runs are therefore increasingly important. Multistage process surveillance and fault diagnosis have become a necessity. Process control incorporating SPC and hybrid approaches are discussed in this chapter. Overall the chapter helps in building a sound understanding about process control with a flavour of different approaches that are helpful in analysing a process which further helps in taking appropriate decisions.

Key words

statistical process control

control charts

manufacturing

quality

hybrid systems

1.1 Introduction

In today’s dynamic manufacturing environment there is a constant need for improvement in processes. A company cannot rest on past performance and expect to remain successful. Customers’ expectations change rapidly and manufacturing processes have become very demand-driven. More precise specifications present a new challenge that may require the upgrading of existing processes and modern technologies. As a result, process control has become more challenging. Pressure on time and resources, the need for faster delivery, defect-free products, and the reliability and durability of parts and processes, are some of the critical factors facing manufacturing enterprises. Process control plays a key role in building recognition in a competitive market.

Modern technology is capable of the simultaneous control of many variables and the collection of data may appear easy. However, process control also involves costs, for example:

• expenditure on initial analysis of the process,

• expenditure on implementation and integration.

It is important to be aware of the goals and benefits of process control at the outset. Process control can add value if used effectively in decision making, for example:

• If the process is under control, the desired product quality will be achieved.

• If process analysis shows a technology is not serving its purpose, it can be modified or replaced to improve product quality, save costs or improve productivity.

Some basic steps in process control are shown in Fig. 1.1. Some of the tools in process analysis, measurement and control are shown in Fig. 1.2. These techniques are discussed later in the chapter.

1.1 Some steps in process control.

1.2 Process control tools and techniques.

1.2 Process mapping, analysis and control

Product quality is directly dependent upon the process quality. To achieve an excellent quality and defect-free operations process mapping becomes very important. It starts with understanding the process, its approach and the application level and presenting the information with graphical representation. Once the process mapping is done, the control and analysis part comes into picture. This allows us to determine whether the process is in control or not and to analyse if the quality improvement efforts have the desired effect.

This is discussed in detail in the following subsections.

1.2.1 Process mapping

One of the fundamental steps in understanding or improving a process is process mapping. Information about the activities/steps that take place in a process is gathered and mapped so as to create a model representing the complete process. Complex interactions may be represented in a simplified manner. Activities can be grouped into several sub-processes. By the use of process maps, improvement teams are better able to understand the process and become more efficient in ensuring effective control and finding opportunities for improvement.

To ensure process control is effective, the correct product attributes must first be identified. Data or information about the product is collected. The specific characteristics of the product are referred to as the critical attributes and determine the type of measurement. Not all attributes will be critical for the customer. Some may be very important while others may add little value to the product. It is necessary to use appropriate tools to determine a ranking procedure. Among these may be failure mode and effect analysis (FMEA), which analyses the manner in which failure is observed, the causes of the failure, and the effect of failure on the product and other operations.

A process flowchart is an important tool in the construction of a process and provides a snapshot of the complete process. Standard symbols are used for drawing the flowchart. Through process flowcharting, a conclusion may be drawn as to why any redundant operations are being carried out, the final objective being to seek opportunities for process improvement.

A cause-and-effect diagram is also known as...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Woodhead Publishing Series in Textiles
• Foreword
• Part I: General issues
• Part II: Process control in fibre production and yarn manufacture
• Part III: Process control in fabric manufacture, coloration and finishing
• Index