QUALITY CONTROL INSTRUCTIONS QCI NO. 100 REVISION E SPC PROCEDURE WRITTEN BY: R. Zielinski DATE: 2/3/92 APPROVED BY: APPROVED BY: Department Manager Quality Assurance Manager DATE: DATE: SF 118 1
CHANGE RECORD Rev. Description A Changed the ten to seven in paragraph 3.4 RCZ RCZ 3/16/92 3/16/92 Written By Approved By Date Effectivity Date Approved By Date Rev. Description B Added 2.4.2 to include use of SQC computer data storage and capability analysis, also revised control chart format (Attachments 1 and 2). Expanded section 4.0 to include specific steps to set up attribute control charts. DTN RCZ 10/18/96 10/21/96 Written By Approved By Date Effectivity Date Approved By Date Rev. Description C Added 2.1.1 to include designation of variable and attribute charts. Charles Rottner Ray Zielinski 11/28/01 12/3/01 Written By Approved By Date Effectivity Date Mark Lesinski 12/3/01 Approved By Date Rev. Description D Change Production Control to Manufacturing Engineering throughout, Modify paragraphs 2.4.2, 4.1.7, 4.1.20. Add paragraph 6.3 Charles Rottner Ray Zielinski 8/24/04 8/25/04 Written By Approved By Date Effectivity Date Mark Lesinski 8/25/04 Approved By Date Rev. Description E Added following statement to para.2.4.2. Unless specified by customer drawing or purchase order SVT will require a process capability (CPK) 1.33. Charles Rottner Michael Elhage 8/11/08 8/13/08 Written By Approved By Date Effectivity Date Approved By Date 2
1.0 SCOPE 1.1 This procedure covers implementation and maintenance of Statistical Process Control (SPC) in the manufacturing areas of Servotronics, Inc. 2.0 GENERAL REQUIREMENTS 2.1 Production hardware is subject to SPC charting. 2.1.1 The use of variable charts is the preferred method of SPC charting. Variable charts will be designated on the operation sheet with a stamp of SPC-V and attribute charts will be designated on the operation sheet with a stamp of SPC-A. 2.1.2 Unless otherwise specified, charting of variables data refers to the use of Individual and Range (Individual X, Moving R) charts. Ref. SF161. 2.1.3 Attribute control charts (p,np,c,and u charts) will be utilized when charting attribute data and specified where appropriate. Ref. SF162. 2.2 All lot sizes are subject to SPC and the requirements contained herein. 2.3 All chart header information must be completed prior to running the setup part. 2.3.1 Charting that is initiated on one shift will be continued by subsequent shifts where appropriate. 2.4 Dimensional characteristics under SPC control will specified on the operation sheets or other appropriate documentation. This determination will be made by Engineering, Quality, and Manufacturing as a team. 2.4.1 Each dimensional characteristic under SPC control shall have it s own chart. 2.4.2 When a control chart is completed, it shall be submitted to Manufacturing Engineering where the data will be entered into the SPC XL2000 or Mini-Tab computer file. A capability analysis will then be performed on the data. Unless specified by customer drawing or purchase order SVT will require a process capability (CPK) 1.33. 3.0 FREQUENCIES AND CORRECTIVE ACTION 3.1 Unless otherwise specified, the following general rules apply to Individual and Range variables control charts. 3
3.1.1 The following rules do not supersede Servotronics requirement to produce quality hardware. It is everyone s responsibility to strive to attain 100% quality in the components being produced and the processes being performed. Not only must the characteristic selected for SPC control be maintained, but all other requirements, whether specified by drawing or process documentation, must also be within the requirements of the documentation package. This is the responsibility of everyone involved in the process. 3.2 Except as noted, the number or frequency of parts to be charted will be in accordance with lot sizes and Table I. The sample sizes in Table I include the first and last part in each lot that must be charted. Setup parts shall be charted on a separate control chart. The lot run shall be considered to start when all dimensional characteristics are achieved and charting shall be in accordance with Table I. 3.2.1 When a sample frequency other than every part is used and an out-ofcontrol condition arises, plot every subsequent part until 5 consecutive parts are plotted in control. 3.2.2 The control limits (UCLX, LCLX, and UCLR) are to be obtained from the drawing and data package supplied. 3.3 If an individual or range data point is outside the control limit(s), the following action must be taken: 3.3.1 If the operator can solve the problem the appropriate adjustments shall be made and the corrective action documented on the control chart. 3.3.2 If an operator can not solve the problem, they shall notify their supervisor. 3.3.3 If the supervisor can solve the problem the appropriate adjustments shall be made and the corrective action taken documented on the control chart. 3.3.4 If the supervisor can not solve the problem Quality, Engineering and Manufacturing Engineering shall be notified. The problem shall be addressed and the appropriate action taken to correct the problem. All corrective action taken shall be documented on the control chart. When additional documentation is required it shall be referenced on the control chart. If the problem can not be solved within a reasonable amount of time (normally one shift), the Manufacturing Manager shall be notified. 4
3.4 If seven consecutive data points are trending in the same direction, the following action must be taken: 3.4.1 Proceed in accordance with 3.3.1 through 3.3.4. 4.0 CONTROL CHART SETUP 4.1 The chart header shall be filled out as follows (Ref. SF161 and SF162, attached). When additional chart pages are required, only the entries marked * need be entered in the header. 4.1.1 Chart No. (1) * Enter chart numbers: 1 of -, 2 of -, 3 of -, etc.. 4.1.2 Part No. (2) * Enter part number from data package. 4.1.3 Rev. (3) * Enter part revision letter from data package. 4.1.4 Part Name (4) Enter part name from data package. 4.1.5 Model (5) Enter model number, if provided, from data package. 4.1.6 Work Order (6) * Enter work order number from data package. 4.1.7 Deleted, no longer used due to Pro-Man System 4.1.8 Lot Size (8) * Enter number of parts to be produced per the data package. 5
4.1.9 Machine / Equipment (9) Enter machine description or test equipment used. e.g. MTC2, MOOG, Test Stand #, etc. 4.1.10 Document (10) * Enter document that references feature under SPC control. e.g. Op Sheets, EIs, etc. 4.1.11 Op. / Sec. No. (11) * Enter operation number or section number (para. no.) under SPC control from data package. 4.1.12 Dim. / Spec. (12) * Enter dimension or specification and tolerance under SPC control from data package. 4.1.13 Dim. / Spec. Description (13) * Enter brief dimension or specification description: I.D., O.D., hole, current, stroke, etc.. 4.1.14 Date (14) Enter date. If operation spans one or more days, enter next date above and in line with the S/N box for the piece started on that day. 4.1.15 Employee No. (15) Enter operator employee number. 4.1.16 Notes (16) Enter sequential number for note pertinent to piece being run. Enter note reference number and note in appropriate locations on the back of the chart. NOTE: Paragraphs 4.1.18-4.1.22 are for IX-MR charts only. 6
4.1.17 Serial No. (17) Enter the sequential number for the piece being produced. If a large lot is being run, enter the sample sequence number as defined in Table I - 1, 2, 4, 6; 1, 5, 10, 15 etc.. 4.1.18 Measurements (18) Enter the actual dimension or performance parameter that is measured for each part:.0940,.0942,.0938, etc.. 4.1.19 Moving Ranges (19) In the space provided enter the difference between each measurement and the preceding one. The first entry must be zero since a preceding measurement is not available. e.g. (19).0940.0940.0943.0938 (20) 0 0.0003.0005 4.1.20 Measurement Plot (20) Establish an appropriate scale on the chart so the required information can be adequately plotted. Upper control limits (UCLx) and lower control limits (LCLx) should be established and labeled on the left side of the chart. A line from the left to the right side of the chart should be drawn to signify these limits. These limits should be placed on the chart by Manufacturing Engineering before parts are produced. Control limits are established by recording the first 20 consecutive measurements and giving them to Manufacturing Engineering to be entered into the computer software to be calculated. Use the control limits from the previous run as a reference point to achieve continuous improvement. Plot the actual measurement values (18) on the chart. Place a point on the chart at the intersection of the measured value (horizontal line) and the corresponding measurement sequence number (vertical line). Connect the points using straight lines. 4.1.21 Moving Range Plot (21) Establish an appropriate scale on the chart so the required information can be adequately plotted (minimum value of the moving range). 7
The upper control limit (UCLR) should be located and label on the left side of the chart. A line from the left to the right side of the chart should be drawn to signify this limit. This limit should be placed on the chart by Manufacturing Engineering before parts are produced. Plot the calculated moving range points on the chart. Place a point on the chart at the intersection of the moving range value (horizontal line) and the corresponding measurement sequence number (vertical line). Connect the points using straight lines. NOTE: Paragraphs 4.1.23-4.1.26 are for attribute charts only. 4.1.22 Sample Size (22) Enter the number of parts chosen per sample. 4.1.23 No. Defects (23) Enter the number of defects found within the sample size (22). 4.1.24 Chart Type (24) Enter type of attribute chart that will be utilized for SPC control of this feature (p, np, c, u). This should be entered by Manufacturing Engineering. 4.1.25 Attribute Plot (25) Establish an appropriate scale on the chart so the required information can be adequately plotted. Appropriate upper and lower control limits (UCL and LCL) should be established and labeled on the left side of the chart. A line from the left to the right side of the chart should be drawn to signify these limits. These limits should be placed on the chart by Manufacturing Engineering before parts are produced. Plot the appropriate non-conformance ratio (dependent on sample size (22), number of defects per sample (23), and chart type (24)) on the chart. Place a point on the chart at the intersection of the measured value (horizontal line) and the corresponding measurement sequence number (vertical line). Connect the points using straight lines. 5.0 IDENTIFICATION 5.1 Charted parts will be marked for identification. 8
5.1.1 Enter the applicable operation / section number and the number that corresponds with the measurement of that part. e.g. Op. 30 / 10 5.1.2 Subsequent operations which are under SPC control can be added to the bag or tag. Number on tags or bags for different operations are independent from one another. e.g. Chart number 10 from one operation does not need to be number 10 when the hardware is started at the next operation. The component must retain the identification throughout the manufacturing process. This identification must be present when the components are submitted for final inspection. 6.0 FINAL INSPECTION 6.1 Move lot to final inspection for verification. 6.2 Verify lot per requirements of Q.C.I. 101. 6.3 Store completed control charts with attached computer generated capability analysis in Quality Assurance 9
TABLE I (Reference Para. 3.2) LOT SIZE FREQUENCY I. 1-49 Every part charted II. 50-99 Every other part charted III. 100-199 Every fifth part charted IV. 200 and up Every tenth part charted 10
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