1、GEIA STANDARD STATISTICAL PROCESS CONTROL SYSTEMS EIA 557-B FEBRUARY 2006 GOVERNMENT ELECTRONICS AND INFORMATION TECHNOLOGY ASSOCIATION A Sector of the Electronic Industries Alliunc Copyright Government Electronics classification: excellent, good, poor), nominal data (i.e., unordered groupings such
2、as defect type), or pass/fail data. AUDIT: The periodic observation of procedures and performed activities to evaluate compliance with requirements. AVERAGE: The sum of the sample values divided by the number of sample values. A measure of location used to estimate the population mean. BINOMIAL DIST
3、RIBUTION: A specific discrete probability distribution for attributes data. CAPABILITY: The natural variation of the process due to common causes. CAPABILITY INDEX: A measure of the relationship between the specification limits and the capability. See EIA-738, I Guideline on the Use and Application
4、of Cpk“ and “The Use and Abuse of Cpk“ by Berton H. Gunter. CAUSE AND EFFECT DIAGRAM: A tool for individual or group problem-solving that uses a graphic description of the various process elements to analyze potential sources of process variation. Also called a Fishbone Diagram (after its appearance
5、) or Ishikawa Diagram (after its developer). cluster in the absence of a special cause. It is usually set at the average, median, or mode of the points being plotted, or (for a tunable process) at an achievable target value (to detect deviations from the value thought most desirable). attributes dat
6、a can be collected. CENTERLINE: A reference line on a control chart about which the chart points are expected to CHARACTERISTIC: A distinguishing feature of a process or its output on which variables or CHARACTERIZATION: A description of the characteristics of a product or process by CHECKLIST: A li
7、sting of the specified criteria that may be observed and checked off during an CHECK SHEET: A form for data collection. COMMON CAUSE: A source of natural variation that affects all the individual values of the process output being studied. In control chart analysis it appears as part of the random p
8、rocess variation. CONTROL CHART: A graphic representation of a process characteristic showing plotted values of some statistic gathered from that characteristic; a central line and one or two statistically derived control limits. Two basic uses are to determine whether a process has been operating i
9、n statistical control and to aid in maintaining statistical control. causes alone. Variation beyond a control limit may be evidence that special causes are affecting the process. Control limits are calculated from process data and are usually represented as a line (or lines) on a control chart. They
10、 are not to be confused with engineering specification limits. mathematical modeling, design of experiments or statistical data evaluation. audit or inspection. CONTROL LIMITS: The maximum allowable variation of a process characteristic due to common 6 Copyright Government Electronics about 95.44% l
11、ie within plus or minus two standard deviation units of the mean; and about 99.73% of all individuals lie within plus or minus three standard deviation units of the mean. PARAMETER: A numerical characteristic of a population. 7 Copyright Government Electronics the property of being in statistical co
12、ntrol. STABLE PROCESS: A process that is in statistical control. STANDARD DEVIATION: A measure of the spread or variation in a probability distribution (population standard deviation) or in a sample of values measured on the output from a process (sample standard deviation). parameter of the populat
13、ion from which the sample came. variation have been eliminated and only common causes remain. statistical techniques to document, correct and improve process performance. and ensure compliance with requirements. STATISTIC: A value calculated from or based upon sample data used to make inferences abo
14、ut a STATISTICAL CONTROL: The conditions describing a process from which all special causes of STATISTICAL PROCESS CONTROL (SPC): The conversion of data to information using STATISTICAL QUALITY CONTROL (SQC): Statistical methods and procedures used to document TARGET: The desired value for a statist
15、ic of a characteristic or parameter of a process node. TREND: The movement of a process in an increasing or decreasing direction. VARIABLES DATA: A measure of a characteristic where every value within a given interval is VARIATION: The difference among individual outputs of a process. The sources of
16、 variation can be YIELD: The number of units that pass some inspection criteria divided by the number submitted. possible. grouped into two major classes: common causes and special causes. 9 Copyright Government Electronics Republished ASQ, 1980. SHEWHART, WALTER A., From the Viewpoint of Quality Co
17、ntrol, Dover Publications, Inc., New York, 1986. TAGUCHI, GENICHI, Introduction to Quality Engineering, Asian Productivity Organization, Unipub-Kraus International Publications, White Plains, New York, 1986. VAUGHN, RICHARD C., Introduction to Industrial Engineering, Iowa State University Press, Ame
18、s, Iowa, 1967. WALPOLE, RONALD E., .U) Does the SPC system include requirements for determining and characterizing critical process nodes? (3.0) Does the SPC system include requirements for determining gage characteristics and capability? (.3.0) Does the SPC system include requirements for determini
19、ng process characteristics and capability? (33) Does the SPC system include requirements for documenting the process control system? (3.0) Does the SPC system include requirements to utilize appropriate on-line and off-line process control methods? (3.0) Does the SPC system include requirements for
20、determining SPC training needs and ensuring that those needs are fulfilled? (34) Does the SPC system include requirements for suppliers to implement and maintain SPC systems? (20) Does the SPC system include requirements to calibrate all inspection, measuring and test equipment used to measure proce
21、ss/product parameters? (XU) Does the SPC system include requirements for determining what preventive maintenance is needed and how frequently it must be performed? (3.0) Does the SPC system include requirements to perform periodic self audits? (3.0) Is the quality management system documented and ca
22、pable of being audited? (u) 14 Copyright Government Electronics .%.) Have the personnel performing product related SPC activities received adequate and appropriate training to perform those activities? (6.9) NOTE: The training program shall provide the necessary training to management, engineering,
23、technical personnel, production supervisors, operators, and support personnel. Has the training been tailored to individual functions and responsibilities within the organization? (6.9) NOTE: Suggested training topics are presented in Anxex D. Does the training include all of the SPC techniques that
24、 are being utilized? (0) Does the manufacturer have a documented program to encourage suppliers to use Are the SPC methods that suppliers are encouraged to use consistent with this standard? (u) NOTE: suppliers materials and components, criticality to the manufacturers processes, and resources of th
25、e supplier. The objective of statistical control limits is to use on-lineheal-time Statistical control limits should not be adjusted due to shifts/trends. (629 SPC? (6.:.i.L!) The suppliers SPC system may vary based on the complexity of the 17 Copyright Government Electronics & Information Technolog
26、y Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA-557-B Item YN Questions (text reference) 60 Are all instruments used to monitor critical characteristics calibrated in accordance with military standards, indu
27、stry standards, or equivalent international standards (e.g., ANSUASQ M1 and IS0 10012, etc.)? (6.11) Does the preventive maintenance program include use of the equipment manufacturers recommendations during collection of historical data and determination of product and process relationships? (9.12.
28、I) Does the preventive maintenance program contain procedures designed to minimize equipment-induced product and process variability? (6.12.2) Does the preventive maintenance program include identification of the inter- relationships of equipment and product/process characteristics? (6.3 2.3) Does t
29、he preventive maintenance program include a preventive maintenance schedule derived from operating and historical data using statistical andor analytical techniques for critical product and process equipment? (6.12.4) Is a self audit of the SPC system conducted at least once a year? (u) 61 62 63 64
30、65 18 Copyright Government Electronics & Information Technology Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-E IA- 5 5 7-B Annex D - Example of an SPC Plan Outline (SPC System I m p lem en ta t io n P Ian) The
31、SPC plan is a formal document that defines the system, establishes the methodology, identifies the resources, sets the goals and objectives, and schedules the implementation. As the implementation progresses, performance against the plan is evaluated and adjustments are made as necessary to ensure t
32、imely completion. The following may be used as an example: 1.0 PURPOSE This section should describe the purpose of the document, i.e., to formally define a Statistical Process Control System. 2.0 SCOPE This section should delineate areas of the company to which this plan applies and indicate that an
33、 SPC plan is evolutionary in nature. 3.0 GOAL This section should describe goals for utilizing SPC and the basic underlying philosophy of applications. Review of the “Introduction” paragraph of this standard (paragraph Id) should be of assistance. 4.0 GENERAL 4.1 Definitions This section should list
34、 definitions that are applicable to SPC, common to industry, and the company. The “Definitions and Terminology” annex of this standard A) should be of assistance. 4.2 References and Publications This section should list references and publications that are useful in an SPC system. The “References” a
35、nnex of this standard (Annex 13) should be of assistance. Additional specifications and standards may be added to this section, including any in-house quality system specifications, inspection procedures, procedures for nonconforming product, etc. 4.3 SPC Committee This section should denote, by pos
36、ition, the members of an SPC steering committee or team and their responsibilities for maintaining the SPC system plan. The committees purpose is to develop and oversee the implementation of an overall SPC plan. This committee or team may use the following approach as a guideline in planning and org
37、anizing the SPC system: 4.3.1 statistician who thoroughly understands the concepts, technical use and applications of SPC. The committee should be headed by a senior manager or designee. 4.3.2 Provide initial SPC training for the management team to ensure their knowledge of the concepts and philosop
38、hy of SPC. Visit other manufacturers that have had success with their SPC systems. Identify potential pitfalls and roadblocks. 4.3.3 Provide overall awareness training to middle management and line supervisors through the use of seminars or group meetings. Present the concepts, organization plans an
39、d objectives. 4.3.4 Set the objective of the implementation to install and maintain a Statistical Process Control system across the entire process. The SPC system will focus on maintaining consistent processes and Include managers of each function on the committee, including a quality engineer or 19
40、 Copyright Government Electronics & Information Technology Association Provided by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-EIA-557-B reducing variability to provide continuous quality, reliability, and service improvement through
41、 the use of statistical techniques. 4.3.5 production, engineering and quality personnel may form into quality improvement teams for a particular process group. 4.3.6 capability studies, on and off-line control, documentation, training, etc. 4.3.7 the establishment of an SPC system as a major compone
42、nt of the overall operations process. 4.3.8 services as needed to ensure effective execution of the plan. 4.3.9 process flow. 4.3.10 prioritize problems and causes. Use results of this analysis to select the process group to execute the initial introduction of SPC techniques. Look for a chance for e
43、arly success to reinforce the benefits of SPC. Provide the in-depth technical training for the appropriate individuals involved in the initial introduction. 4.3.11 Develop quantifiable performance metrics. Determine initial metrics and set targets for improvement. For example, a product quality meas
44、ure such as quality costs can be used to track overall improvement. Review performance and issues at regularly scheduled staff meetings. Present the concepts, organization plans, and objectives. 4.3.12 Provide operator training just prior to and during the introduction of SPC into their area. Involv
45、e the line supervisors in the operator training. 4.3.13 Use the statistical methodology of paragraph .ii, for implementation of SPC in the selected process group. 4.3.14 Revise existing procedures and develop new procedures as necessary, to include the SPC system in the overall quality system and op
46、erations process. 4.3.15 After a successful start with the initial implementation, review the strengths and weaknesses of the implementation process, adjust the strategy as necessary, expand the SPC system implementation to the other areas until the entire process has been included. 4.4 Training Thi
47、s section should describe the approach to SPC training, including who trains, who receives the training, how often, how the concept of training is approached (i.e., team training, self managed work teams, self study, etc.), and a general listing of topics and techniques for SPC training, (i.e., Pare
48、to charts, basic statistics, problem solving techniques, etc.). Suggested topics for an SPC training program are: From the process flow, group related processes and associated operations so that Identify the organizational responsibilities for performing process characterization, Prepare a timed act
49、ion plan that commits the involvement of all levels in the organization to Determine the resources needed. Use in house experts, external consultants or purchased Develop and document the rationale for determining the critical operations in the overall From historical data, use problem-solving techniques such as Pareto analysis, etc., to a. Definitions, terminology and philosophy of SPC b. Basic problem solving 0 Pareto analysis 0 Cause and effect diagrams 20 C
