Process Capability
Process Capability
A process is the value-added transformation of inputs to outputs. The inputs and outputs of a process can involve machines, materials, methods, measurement, people, and the environment. Each of the inputs is a source of variability. Variability in the output can result in poor service and poor product quality, both of which often decrease customer satisfaction. It is necessary to analyze the amount of common cause variation present in an in control process. Process capability is the ability of a process to consistently meet specified customer-driven requirements. There are many methods available for analyzing and reporting process capability.
• Customer Satisfaction and Specification Limits
Quality is defined by the customer. A customer who believes that a product or service has met or exceeded his or her expectations will be satisfied. The management of a company must listen to the customer and translate the customer’s needs and expectations into easily measured critical to- quality (CTQ) variables. Management then sets specification limits for these CTQ variables.
Specification limits are technical requirements set by management in response to customer’s needs and expectations. The upper specification limit (USL) is the largest value a CTQ variable can have and still conform to customer expectations. Likewise, the lower specification limit (LSL) is the smallest value a CTQ variable can have and still conform to customer expectations.
For example, a soap manufacturer understands that customers expect their soap to produce a certain amount of lather. The customer can become dissatisfied if the soap produces too much or too little lather. Product engineers know that the level of free fatty acids in the soap controls the amount of lather. Thus, the process manager, with input from the product engineers, sets both a USL and a LSL for the amount of free fatty acids in the soap.
If a process consistently meets these requirements, the
A process is the value-added transformation of inputs to outputs. The inputs and outputs of a process can involve machines, materials, methods, measurement, people, and the environment. Each of the inputs is a source of variability. Variability in the output can result in poor service and poor product quality, both of which often decrease customer satisfaction. It is necessary to analyze the amount of common cause variation present in an in control process. Process capability is the ability of a process to consistently meet specified customer-driven requirements. There are many methods available for analyzing and reporting process capability.
• Customer Satisfaction and Specification Limits
Quality is defined by the customer. A customer who believes that a product or service has met or exceeded his or her expectations will be satisfied. The management of a company must listen to the customer and translate the customer’s needs and expectations into easily measured critical to- quality (CTQ) variables. Management then sets specification limits for these CTQ variables.
Specification limits are technical requirements set by management in response to customer’s needs and expectations. The upper specification limit (USL) is the largest value a CTQ variable can have and still conform to customer expectations. Likewise, the lower specification limit (LSL) is the smallest value a CTQ variable can have and still conform to customer expectations.
For example, a soap manufacturer understands that customers expect their soap to produce a certain amount of lather. The customer can become dissatisfied if the soap produces too much or too little lather. Product engineers know that the level of free fatty acids in the soap controls the amount of lather. Thus, the process manager, with input from the product engineers, sets both a USL and a LSL for the amount of free fatty acids in the soap.
If a process consistently meets these requirements, the