Ian DavisonLinda DonoghueDavid Fransman

Noah Zenker

Introduction

Critical to all aspects of manufacturing, from design to packaging and beyond

Quality StandardsStatistical Process ControlQuality Inspection EquipmentFailure Testing

Linda Donoghue

Six SigmaDeveloped by the Motorola CompanyMethod of improving quality by reducing

variability in products and processesData driven decision makingDefined 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 repeatabilityOnly 3.4 defects per million allowedResults in fewer defects, lower costs, greater

customer voice

Figure 36-19 DeGarmo's Materials & Processes in Manufacturing

Lean Manufacturing

Maximize efficiency while minimizing wasteDesires continuous operation with 100%

partsFirst-time quality

In-process quality checksPlanningPin points priority areas of quality

consideration

ISO Standards

International Organization for Standardization

Main purpose is to create internationally agreed upon standardsLess variabilityGreater promotion of worldwide competition

Voluntary, but highly regarded standards

ANSI StandardsAmerican National Standards InstituteNational standards which help meet the

internationally declared ISO standardsValuable for market acceptanceUnlike ISO, ANSI does not create the

standards, only supervises the development and use of standards

ISO and ANSI in ManufacturingOften set the bar for government regulations

Operator qualificationsDimensioning and tolerancesAcceptable use of machinery and toolsRequirements for automation software, coding,

symbols, and terminologySafety and testing requirementsMaterial handling requirements

GMPGood Manufacturing PracticeGuidelines for manufacturing processes that

affect quality in Food productionMedical devicesPharmaceuticals

Lawfully enforced by the FDAIncludes batch records, distribution tracking,

testing, operator training, etc.

Noah Zenker

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

Statistical Process Control – Graphical Representation

Benefits of SPCProvides a method of surveillance and feedback for keeping

processes in controlSignals when a problem with the process has begun and is

about to affect quality adverselyDetects assignable causes of variation or root causesReduces the need for inspection due to predictabilityMonitors process quality at the sourceProvides a mechanism to make process changes and track

the effects of those changesOnce causes of variation have been eliminated, SPC

provides ongoing process capability analysis with comparison to the desired outcome

Requirements for SPCProcesses being considered for SPC must:

Be well defined

Have attributes with observable measures

Be repetitive

Be sufficiently critical to justify monitoring

SPC Implementation Pitfalls Measurement variability

The process of measuring must be uniform throughout the process.

Incorrect goals for SPCControl charts should be constructed so as to detect

process trends rather than individual nonconforming events

Poor follow-upSPC 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.

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

SPC ConclusionSPC significantly improves profit and adds

value by:Improving product and service qualityImproving productivityStreamlining processesReducing wasteReducing environmental emissionsImproving capacity and predictive outcomes

Ian Davison

Quality Inspection MethodsThere 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.

Quality Inspection EquipmentThere 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.

Single Purpose Inspection GaugesThere 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.

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).

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.

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.

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.

Visual Inspection EquipmentThere are three types of visual inspection

equipment: Optical Comparators (also known as a

shadow graph)Toolmakers MicroscopeCNC Optical measurement instruments

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 read-out.

Tool Makers MicroscopeA 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 read-out 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.

CNC Visual Measurement SystemsHighly 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.

David Fransman

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.

Failure Testing MethodsTensile 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

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

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

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

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

Failure Testing Defines QualityPerformance

Does the product withstand the customers operating conditions?

LongevityDoes the life of the product be what your

customer wants?Safety

When a product fails could it potentially cause harm to the customer?

ConclusionQuality Systems in Manufacturing

Quality StandardsStatistical Process ControlQuality Inspection EquipmentFailure Testing

Questions ? ? ?