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Introduction to Statistical Process Control

Autor:   •  March 16, 2018  •  13,875 Words (56 Pages)  •  617 Views

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The primary goal of SPC is to minimize production cost. This is accomplished with a “make it right the first time” program. This type of program can eliminate cost associated with making, finding, and repairing substandard products. Besides, SPC attain a consistency of product and services that will meet production specifications and customer expectations. Reduce product variability to a level that is well within specifications so the process output will match the desired design quality. This consistency leads to process predictability, which benefits the company by helping management meet quantity targets.

INTRODUCTION TO TEXTILE HUMIDIFIER AND HUMIDIFICATION SYSTEM

The humidity is an important part in the manufacturing process of textile which is yarns and fabrics. Humidity control in the textile industry is essential to maintain product quality and reduce imperfections. The proper textile humidity will improve the moisture regain, maintain the yarn strength, reduce the yarn broken problem, reduce static build-up, maintain product weight, reduce fly and micro-dust, provide free cooling, and provide a healthier and more comfortable working environment.

The reason of humidification is because of all the textiles are hygroscopic. That is, they absorb or release moisture depending on the relative humidity of the surrounding air. If the atmosphere is drier than the textile’s equilibrium relative humidity then the textile will give up its moisture to the air. If the air is very humid then the textile’s moisture content will increase. This moisture loss and gain occurs at every stage from the initial processing of the fibers through to final garment manufacturing, distribution and use by the consumer.

The most effective way to humidify a textile plant is to use a compressed air and water spray system, such as the Jetspray from Condair. Rows of precision engineered nozzles are mounted in the roof space and combine compressed air and water, releasing a fine mist. This mist resembles pressurized steam and contains droplets of just 7.5µm, which rapidly evaporate to raise the humidity to the required level.

This type of spray system is easy to install and provides very reliable and hygienic humidity control. It is also flexible and easy to locate, which is convenient in situations where machinery and processes can periodically be relocated. The capacity of the humidification system can be increased in size or modified simply by adding more nozzles. On a quality system, an individual control panel should be able to accommodate rows of nozzles releasing a total of up to 600 liters of water per hour. This could typically humidify a textile manufacturing area of around 100,000m3.

Optimal humidity in textile manufacturing has many benefits that will enhance profitability. These include improving product quality, maintaining product weight, reducing machine downtime and improving employee comfort. The most important thing to remember when considering humidity control is to get good advice from an expert with experience in the textile industry. There are many different issues involved with humidification of textile plants and as the issues described above demonstrate, getting it wrong can be an expensive mistake.

2.0 Basic concepts of statistical process control

2.1 Introduction to Quality Concepts and Statistical Process Control

Statistical Process Control is a tool that’s applies basic statistics to control processes. A process is any collection of people, material, methods, equipment, measurement, and environment that produces a certain output. Statistical process control is a method of gathering and analyzing data to solve practical quality problems. The term statistical means that we will be drawing conclusion from numbers. Processes refer to the fact that we will be concerned with a specific production process and its ability to produce output having consistent quality. Control means that we will monitor a process and adjust it when necessary so that it will perform in the manner that it is intended to perform. A process is not predictable if special causes of variation exist. Special causes of variation can usually be found and corrected, particularly if you know when they are occurring. At times, even special causes of variation are difficult to find. Some refer to the total variation of a process as the natural tolerance of the process. Keep in mind that a process will produce parts according to its own inherent variation regardless of the product specification. The important things is to control the process, then make sure that the natural tolerance is less than the specification tolerance, which defines whether or not the product is acceptable. It is intended that most parts produced will be near nominal size. This is called process capability.

2.1.2 What is Quality?

Quality can mean different things to different people and can be interpreted in a variety of ways by an individual. Quality may be thought to have two main division is the quality of a manufactured product and the quality of services received. From a manufacturing standpoint quality is simply conformances to specification. The ultimate customer could describe quality as fitness for use. When trying to edge out the competition, quality can be interpreted as producing the very best product or providing the very best service. In some industries a set of classification have been established by design quality.

For example, several level of design quality in the textile manufacturing industry that we are chosen is Jetspray, from top of the line expensive design down to cheap design than the quality base on the fabrics. At each level, however, the buyer would expect good conformance quality. In fact, textile manufacturer encourage in level comparison to show that Jetsparay have conformance quality in their level.

Quality also can link to customer satisfaction. Some companies have used that definition for years, but there is now a broad move toward defining quality as total customer satisfaction. To use that definition, a company must know its customer, and in the multilevel markets, it must know the customer at each level for which it produce. The customer is becoming the driving force for quality.

One more recent development in the definition of quality is that of exceeding the customer expectations. When the service is so good that the customer feels “special” when a product has an outstanding feature, or when the combination of product, service and delivery leaves the customer truly amazed, the customer expectation have been loyal customer base.

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