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  • Production variable examples 
  • Reference:
  • Measurement Variability - Consistent measurements cannot be expected from software processes that are not documented and generally followed. The process of measuring must be uniform throughout the process.
    Incorrect goals for SPC - Control charts should be constructed so as to detect process trends, not individual nonconforming events.
    Poor follow-up - SPC only signals the possible existence of a problem.  Without detailed investigations, as in an audit, and instituting corrective action, SPC will not provide any benefit.
  • Qc presentation

    1. 1. Ian Davison Linda Donoghue David Fransman Noah Zenker
    2. 2. Introduction Critical to all aspects of manufacturing, from design to packaging and beyond Quality Standards Statistical Process Control Quality Inspection Equipment Failure Testing
    3. 3. Linda Donoghue
    4. 4. Six Sigma Developed by the Motorola Company Method of improving quality by reducing variability in products and processes Data driven decision making Defined by the statistical levels expected for compliance  standard deviation of less than six sigma from the mean to the most extreme specification limits Requires high precision and repeatability Only 3.4 defects per million allowed Results in fewer defects, lower costs, greater customer voice
    5. 5. Figure 36-19 DeGarmo's Materials & Processes in Manufacturing
    6. 6. Lean Manufacturing Maximize efficiency while minimizing waste Desires continuous operation with 100% parts First-time quality In-process quality checks Planning Pin points priority areas of quality consideration
    7. 7. ISO Standards International Organization for Standardization Main purpose is to create internationally agreed upon standards Less variability Greater promotion of worldwide competition Voluntary, but highly regarded standards
    8. 8. ANSI Standards American National Standards Institute National standards which help meet the internationally declared ISO standards Valuable for market acceptance Unlike ISO, ANSI does not create the standards, only supervises the development and use of standards
    9. 9. ISO and ANSI in Manufacturing Often set the bar for government regulations Operator qualifications Dimensioning and tolerances Acceptable use of machinery and tools Requirements for automation software, coding, symbols, and terminology Safety and testing requirements Material handling requirements
    10. 10. GMP Good Manufacturing Practice Guidelines for manufacturing processes that affect quality in Food production Medical devices Pharmaceuticals Lawfully enforced by the FDA Includes batch records, distribution tracking, testing, operator training, etc.
    11. 11. Noah Zenker
    12. 12. What is Statistical Process Control? Constant in-process sampling of a production variables  Data points are compared to average (Control chart)  Problems isolated  Modifications made to flagged area(s)  Repeat  Never ends while product still being produced
    13. 13. Statistical Process Control – Graphical Representation
    14. 14. Benefits of SPC  Provides a method of surveillance and feedback for keeping processes in control  Signals when a problem with the process has begun and is about to affect quality adversely  Detects assignable causes of variation or root causes  Reduces the need for inspection due to predictability  Monitors process quality at the source  Provides a mechanism to make process changes and track the effects of those changes  Once causes of variation have been eliminated, SPC provides ongoing process capability analysis with comparison to the desired outcome
    15. 15. Requirements for SPC Processes being considered for SPC must:  Be well defined  Have attributes with observable measures  Be repetitive Be sufficiently critical to justify monitoring
    16. 16. SPC Implementation Pitfalls Measurement variability  The process of measuring must be uniform throughout the process.  Incorrect goals for SPC  Control charts should be constructed so as to detect process trends rather than individual nonconforming events  Poor follow-up  SPC only signals the possible existence of a problem.  Without detailed investigations, as in an audit, and instituting corrective action, SPC will not provide any benefit.
    17. 17. Example of SPC in action  Statistical Process Control used by Raytheon  Wanted to monitor solder defects in surface mount assembly (Insufficient or excess solder)  Raytheon used SPC to constantly monitor the soldering application  Solder screen condition  Solder screen tension  Squeegee pressure  Squeegee speed  Solder past viscosity  Solder paste particle size  SPC gave Raytheon:  Improved process capability  Higher quality  Increased yield in surface mount assembly
    18. 18. SPC Conclusion SPC significantly improves profit and adds value by: Improving product and service quality Improving productivity Streamlining processes Reducing waste Reducing environmental emissions Improving capacity and predictive outcomes
    19. 19. Ian Davison
    20. 20. Quality Inspection Methods There are two main ways to inspect the quality of a part for dimensional accuracy and quality specifications. Tactile: Using an instrument that comes in contact with the part to measure and quantify aspects of a part or component. Visual: Using an instrument that does not come in contact with the part, but uses visual methods of comparison to quantify aspects of a part or component.
    21. 21. Quality Inspection Equipment There are two main categories of quality inspection equipment. Gauges: a piece of equipment designed specifically to measure a single part or component. Metrology Equipment: A piece of equipment versatile enough to measure a wide range of parts, typically requiring a custom fixture to hold each part.
    22. 22. Single Purpose Inspection Gauges There are two kinds of gauges: Go/No Go Gauges, and Variable Measurement Gauges. Go/No Go example: Testing the size of a .125” pin with a bilateral .005” tolerance. If the Pin fits through a hole of size .130” without jamming and does not fit through a hole of size .1245”, the pin will pass a Go/No Go quality inspection. If the pin does not fit through the .130” hole or slips through a .1245” hole, the pin will not pass a Go/No Go quality Inspection. A Variable Measurement Gauge would be a measurement instrument designed to measure one type of part but be able to output a wide range of measurements. These kinds of gauges can also be used to monitor the manufacturing process and catalog trends of certain aspects or dimensions of a particular part.
    23. 23. Indicators – The Most Basic Tactile Inspection Instrument •Dial indicators and digital drop indicators are the most basic form of tactile measurement instrumentation second to a ruler, calipers, and micrometers used for dimensional inspection and would fall into the metrology equipment category. Indicators can be used on their own mounted to a versatile stand, or incorporated permanently into a single purpose gauge. •Dial indicators can measure parts with an accuracy between .001” and .005” depending on the unit. •Digital drop indicators can measure down to 0.00005” accurately (arguable).
    24. 24. Variable Measurement Gauge Above is an example of a fixture for a variable measurement gauge. The part would be clamped by the De-Sta-Co clamp and put under a drop indicator. The indicator would be zeroed on the surface that the pins come out of (Datum Surface) and then the probe would be lifted and placed on the part surface. The measurement would be recorded.
    25. 25. Go / No Go Gauge  Above is an example of a Go / No Go Gauge. This particular gauge was used to ensure the slot width of a not yet released part was within specification. The Go shim of this gauge has a thickness of .012”, the No Go shim of this gauge has a thickness of .01335”. Both shims were made with a Wire EDM. The shims were verified with a drop indicator, a toolmakers microscope, and an optical comparitor. The latter two of which will be detailed later in this presentation.
    26. 26. Coordinate Measurement Machine (CMM)  The CMM is typically a CNC machine that uses a tactile probe to trace the profile of a part and measure particular internal and external features.  The CMM works in 3 dimensions and the X and Y axes typically ride on a compressed air buffer.  CMM’s can also use visual, laser, white light, or air cushion touchless probes.  Some of the best CMM’s have a resolution of 0.000004”.  The CMM is one of the most precise pieces of tactile quality inspection equipment.
    27. 27. Visual Inspection Equipment There are three types of visual inspection equipment: Optical Comparators (also known as a shadow graph) Toolmakers Microscope CNC Optical measurement instruments
    28. 28. Optical Comparator  An Optical Comparator is a measurement device with an XY table, a stage, a light source, various lenses, and a projection screen.  The light is shone on a part placed in a fixture on a the stage, the shadow is cast into the lens, the shadow is then reflected through mirrors and cast onto the screen.  The screen has graduations on it and an origin.  Typically a quality inspector would zero the XY read-out with the origin placed on a feature, the table jogged until the origin lies on the desired feature to be measured, and the measurement recorded from the readout.
    29. 29. Tool Makers Microscope A tool makers mic is a more direct version of a comparator. There is a combination of top and back stage lighting and a set of crosshairs in the microscope eye piece. Typically there is a digital readout integrated with the stage. The crosshairs are zeroed on the edge of a part, the stage jogged until the crosshairs are at the other edge of the desired feature, and a measurement taken from the read-out.
    30. 30. CNC Visual Measurement Systems Highly advanced optical measurement systems using both lasers and digital imaging in conjunction with software able to recognize and measure features from images taken by the machine. Multiple features can be measured in one run. Measurement accuracy down to a few microns.
    31. 31. David Fransman
    32. 32. Failure Testing Failure testing: a way of ensuring a product will not fail under different circumstances and situations of stress, weather, temperature, and etc. Testing allows an engineer to match up their predictions to real life applications. The results will help the designer rethink the product and make necessary changes to meet the customers needs. Since quality control ensures a product meets customer needs, testing can be considered a way to influence product quality.
    33. 33. Failure Testing Methods Tensile testing Determines how a material reacts to the applied tensile forces. You can find ultimate tensile strength, modulus of rigidity and stain. Inexpensive after initial investment Simple to implement. Images.google.com
    34. 34. Failure Testing Methods Cont. Wear testing Determines the effects of continuous contact between two surfaces.  You can find the friction factor and amount of wear to a surface. Simple to implement Inexpensive after initial investment is made. Images.google.com
    35. 35. Failure Testing Methods Cont. Chemical Resistance Test Determines the ability of a material to resist changes in its physical properties when exposed to certain chemicals. You can find the rate at which a chemical reacts a product. Testing with certain chemical can be dangerous. Images.google.com
    36. 36. Failure Testing Methods Cont. Fatigue Testing Determines the number of times an object is able to withstand before failing. You can determine how long it takes the product to fail. Testing machines are used to apply cyclic loads so you can easily model test to mimic a real life cycle pattern. Images.google.com
    37. 37. Failure Testing Methods Cont. Testing at the extremes. Test done beyond the normal operation conditions of a product. You can determine the time it takes to fail. You can also detect unsafe failure at these certain conditions. Images.google.com
    38. 38. Failure Testing Defines Quality Performance Does the product withstand the customers operating conditions? Longevity Does the life of the product be what your customer wants? Safety When a product fails could it potentially cause harm to the customer?
    39. 39. Conclusion Quality Systems in Manufacturing Quality Standards Statistical Process Control Quality Inspection Equipment Failure Testing Questions ? ? ?