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Quality and Automated Process Gauging
Published in Stephan D. Murphy, In-Process Measurement and Control, 2020
Tolerances are set to ensure that the completed product will perform consistently and reliably according to specification and to ensure product uniformity. It is important to distinguish between the tolerances needed to ensure that the product will function and will continue to function reliably and the tolerances which serve only to control product uniformity. For convenience, the former will be referred to as function tolerances and the latter as uniformity tolerances. The basic dimensions to which these tolerances are applied will be referred to as function specifications and uniformity specifications. Unless specifically noted, it should be assumed that tolerances are symmetric, that is, the lower specification limit is the basic dimension minus one half the tolerance and the upper specification limit is the basic dimension plus one half the tolerance.
Measurement Strategies of CMM Accuracy
Published in Salah H. R. Ali, Automotive Engine Metrology, 2017
There are three types of tolerances: the form, position, and size tolerance. The form tolerance is the largest possible deviation of an element form. Deviation of work piece form is the value of the deviation of the real form to its nominal design form. Irregularities of surface can be decomposed into form, waviness, and roughness. Waviness is the important variable of the geometric dimension and tolerance in engineering metrology. Waviness includes five different effective parameters: straightness, flatness, roundness, cylindricity, and surface profile. Roundness is an essential parameter for any circle and cylinder measurements. To measure roundness, it should include a rotational factor to the measurement, conversely, diametric measurement.
System
Published in Sasho Andonov, Bowtie Methodology, 2017
A simple example for this is any kind of situation in the industry production. The production of products in industry by its ontology assumes that normal process will produce normal products. By definition, in the Statistical Process Control (SPC), a normal process* is a process adjusted to produce products that satisfy the specifications expressed by tolerances. Tolerances are limits for the variables of each process parameter. So, this way you have considerably more good products (success produced by normal functioning of the processes) compared with the number of scrap that are products resulting from abnormal functioning of the processes (failures).
An optimization model of make or buy decision and quality improvement of components using rebate
Published in Cogent Engineering, 2020
Cucuk Nur Rosyidi, Namrotul Uela Fatakunul Imamah, Wakhid Ahmad Jauhari
Improving quality of a product or component is not an easy task. Hence, a proper tolerance design is necessary to control the variance of the product (Mustajib & Irianto, 2010). Tolerance serves to limit the variability around the product quality characteristics target. According to Zhang (1996), tolerance is a critical issue in product and process design stage, since it will become the connector between product requirement and manufacturing cost. The tighter the tolerance of a component, the higher the manufacturing cost, and conversely the looser the tolerance of a component the lower the manufacturing cost (Chase et al., 1990). Quality loss will be incurred when product quality does not conform to the predetermined quality target. Therefore, quality improvement has to be performed continuously by reducing the variance of the product (Harrington, 1987).
Implementation of an operating procedure for quality control at production level in a RMG industry and assessment of quality improvement
Published in The Journal of The Textile Institute, 2018
Chowdhury Jony Moin, A. B. M. Sohail ud Doulah, Mohammad Ali, Ferdous Sarwar
Process capability indices, such as Cp and Cpk have been widely used as statistical tools to assess the manufacturing process performance. This is also a widely used statistical process control technique, to determine the ability for manufacturing process between tolerance limits and engineering specifications providing quantitative measures of process potential and performance (Statisti & Tehnike, 2009). It indicates the directions and magnitude of corrections and overall improvement. So, the producer can take steps to improve or redesign the process. For the process capability analysis following, four capability indices were widely used (Montgomery, 2007).Cp = Process Potential Index.Cpk = Process Performance Index.Cpu = Upper Process Performance Index.Cpl = Lower Process Performance Index.
A study of tolerance allocation and stack-up analysis to improve the assembly precision of an injection mold
Published in Journal of the Chinese Institute of Engineers, 2023
Yuo-Tern Tsai, Kuan-Hong Lin, Chun-Sheng Chen
The precisions of CNC machining and surface grinding must be considered since the parts are mainly processed by the machines. The common tolerances of CNC machining can be referred to the data in Table 3. The tolerances in the table are set for the measurements on linear or angular including chamfers and other circular parts. There are four classes of tolerance defined based on the sizes of parts: very coarse, coarse, medium, and fine. The data give general information on tolerance designing for the parts processed by CNC machining. For some advanced CNC machines, the processing tolerances may be smaller than the values in the table.