Assembly Variation Analysis Objective Development for

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Assembly Variation Analysis Objective Development for Proactive Design integrity

Praveen Gomer

[email protected]

248-576-1987

mailto:[email protected]

SEE WHAT YOU’RE MISSING U2U Conference 2

Variation in System;

Tolerances are inevitable

Systematic allocation

of tolerances

Assembly/Performance

requirement

Tolerances based on manufacturability & historic data

GD&T concepts and its

Application

Introduction to Dimension Management

Dimensional

Management

Geometric effects on

functionality

Measurement

SEE WHAT YOU’RE MISSING U2U Conference


VSA : Modeling Operation Overview

4

• 3D data in *.model format • 2D drawing and GD & T • Assembly sequence • Mfg. Process Information • Manual Stack sheet

• ToL files • Process report with major

Contributors • Recommendations

• Definition of objectives and assembly sequence

• Applying GD & T on the participating features

• Performing derivative analysis • Comparing with manual stack up

• Observed that manual stack did not consider effects of relevant tolerances

• New DRF evaluation • Prediction of % yield • Identification of Sensitivities &

contributors

Deliverable Inputs

Value addition

Variation Simulation

Analysis

Execution


Variation Simulation Analysis – Execution Steps

CAD Data

Measurement Objectives Definition

Joints Creation

Application of Constraints and GD&T

Simulation

Result Analysis Using Analyzer

CAD Assembly Created


Design Specification

6

Proactive Reliability Process (Draft)

Design Specifications

& Selection Guidelines

EBR Diagram and Matrix*

Noise Matrix

Functional Block

Diagram

DFMEA

DVP&R

Standard Test Guidelines/Procedure

PF

Core Design Process

*Event Based Reliability and Performance Testing

Quantum Quality Matrix FMEA

Robust Reliability Design?

Reliability-Based DFSS

Y

Severity ≥ 9and SO>20?

N

Fault Tree Analysis(1)

Y

Design Change

Design Change

Design Change

N

Prioritize Noise

1: Must be performed all ISO 26262 Hazard Analysis based Effects

The individual component level will use the drawing to establish dimension related functions


Function Block Diagram

7

The Functional Block Diagram documents the input items, the items which will be used to create the design (the scope), and the output items (where the Primary function will provide its outputs).

The input Items receive dotted lines. The direction of the arrow will show that the input functions are coming into the design. Inputs are conditions for success. When the condition is of poor quality, the input becomes a cause. The functions required for the must be documented in a verb-noun format. Their purpose to be satisfied by each input needs to be defined (e.g. energy for work, signal/timing for action, start of a challenge, response time, etc.).

Functional Blocks are Items which have solid lines. Each functional block must have its function(s) described in a verb-noun format. Place the functional blocks in their time/energy transfer sequence. Show how inputs enter into specific functional blocks.

Identify the Primary Function(s) of the Functional Block Diagram. Primary Functions are outputs to other functional block diagrams of a vehicle. Outputs will be actions, energy transfers, information (digital/analog), reactive structures, etc.

Output Items receive dotted lines. Output items are used to question how poor quality Primary functions will be noticed as effects.

The functional block diagram is an important tool to be used in developing a design, creating a P-Diagram, or creating a Failure Mode and Effects Analysis.

© Chrysler, LLC

Design Specifications

& Selection Guidelines

P-DiagramNoise Matrix

Functional Block

Diagram

DFMEA DVP&R

Standard Test Guidelines/Procedure

Design Structure, Specifications,

Guidelines, and Standard Tests

Ideal Functions, Design Parameters, Noise

Factors, Noise Map to Standard Tests

Structure of Functions, Failure Modes, Causes,

Recommended Actions/Risk

Reduction

Functions

Ideal FunctionsFunction Flow, Ideal Functions, and Conditions for Success, Areas of Causes, and Areas of Effects

Test Conditions

PFStructure

Function Based DVP&R

Design Change Recommendations

Event Based Reliability and Performance

Testing


Boundary Diagram


Bearing Function Model


Crankshaft Function


DFMEA

11

• Each function can respond poorly and become a failure mode. There are three categories of failure modes: The magnitude can be wrong, have unacceptable variation, and the function can respond too quickly/slowly.

• Before assessing the failure modes, the magnitude of the function (what it is and how it might be measured/controlled should be understood). Example: “engage pin” might really mean “move distance.” Understand the actual and simple physics of the function.

• These three categories produce the Seven Failure Modes: omission, excessively, incompletely (the magnitude failure modes), erratically, unevenly (the variation failure modes), too slowly, and too quickly (the timing/rate of energy transfer failure modes)

• These concepts are simple and direct but they do need to be practiced to be really understood.


Moving Towards the DFMEA

12

When the functions from the Items within the scope of the Functional Block Diagram (FBD) perform flawlessly, the Primary Functions will perform flawlessly.

When one of the functions performs poorly, the Primary function will perform poorly.

A function which performs outside acceptable levels becomes a Failure Mode and is described in one of seven ways of performing poorly (The Seven Failure Modes or 7FM).

Before a DFMEA can be performed, the Functions must be documented. For the DFMEA—DVP&R path, the operating specification for the Primary Functions must be documented.

For the Design path, the quality of the inputs (operating ranges/specs), all functions, and the Primary functions must be documented. The operational noise factors will also need to be documented. The following format can be used to document, in a single overview page, all this information.

© Chrysler, LLC


Moving Towards the DFMEA

13

The following function table can be expanded to include two more topics which are inputs and noise factors. Noise factors are determined through regional studies local studies. Local studies performed by taking the Functional Block Diagram into a P-diagram (covered later)

The input specifications define the functional quality of the input (target, max, min, quality etc).

In the example on this page, where the acceptance criteria/test target states “Design:” shows where the DRE needs to address the quality of the action/energy transfer (function). If the function is to be provided by a supplier design, this would be the next level down’s Primary function (supporting this level’s Primary function) which would require its own DFMEA/DVP&R.

© Chrysler, LLC

System, Sub-system, Part/Component Detail Function(s)

Primary Function Performance Specification

Criteria (DVP&R)

List the Item to be Studied Verb-Noun Acceptance Criteria/Test Target

1 PCM Provide Power Design: PWM Spec output to position the

actuator2 Actuator Move Actuator Pintle Design: Distance and speed/reaction time

specification in reaction to PCM signal3 Oil Control Valve Control Oil Flow Design: Flow Quantity, Oil Pressure, Response

Time (document the specifications required to

perform work)4 Cam Phaser Assembly Position Cam Shaft Primary Function: Required for DFMEA/DVP&R

Path: Response time, position accuracy

5 Cam Shaft Activate Valves Out of scope6 Cam Shaft Target Wheel Provide Reference Target Design: Define max angle error7 Oil Circuit Provide Oil Flow Design: Define min flow, pressure, oil quality8 Valve Cover Position Actuator Design: GD&T Target and USL/LSL9 Cam Sensor Provides Cam-Position-Signal Design: Define response time, max angle error

10 Crank Sensor Provides Crank-Position-Signal Design: Define response time, max angle error


Function Block Diagram

14

In this example, Time Cam Event is the Primary function. The sub-functions are supplied in sequential order from the PCM, Actuator, Oil Control Valve, to the Cam Phaser Assembly. Another sequence is from the Oil Circuit to the Oil Control Valve to the Cam Phaser Assembly. The team can now follow time/energy through a design.

© Chrysler, LLC

4 Cam Phaser Assy

1 PCM

Oil Pump

9 Cam Sensor

10 Crank Sensor

5 Cam Shaft6 Cam Shaft

Target Wheel3 Oil Control

Valve2 Actuator

Valve Cover

8 Timing Drive

7 Oil Circuit

Crank Shaft

Oil Temperature Sensor

Oil Pressure

Battery Voltage

Provide oil-temp-signal

Provide oil-pressure-signal

Provide Duty Cycle

Move Actuator Pintle

Control Oil Flow

Primary Function: Position Cam-shaft

Control liftProvides Reference

Target

Drive Cam-Phaser

Position Actuator

Provides Cam-Position-Signal

Provides Crank-Position-Signal

Provides Reference Target

Provides Power

Provide Oil Pressure

Provide Oil Flow

Produce Torque

Work Energy

Work Energy

Response Time

Response Time

Response Time

Timing

Timing

Engine

Driveline

Drivability/Customer

Only to Consider Effects

Noncompliance with Regulatory Requirements

Pedal Position

Engine Speed (Crank Sensor)

Challenge

Challenge

· Too much overlap· Not enough overlap· Misfire· Rough Running Engine· Poor Emissions· Walk Home· Engine Delay· NVH· Slow to respond· Knock

Provide Engine Speed

Provide Customer Request

Specifications can be developed for the inputs, functions, and Primary functions.


Valve train Variation Simulation Analysis

15

Unstable valve train dynamics

Noise, inadequate lash compensation, incorrect valve motion, failed valve

train

Poor Valve Sealing

Poor Valve to Valve Seat Sealing

Binding spring coils, dropped valve, engine

failure

Lash Adjuster Stoke Calculation

Cam Bore Machining Stock Calculation

Installed Valve Spring Height Calculation

Sealing between Valve and Valve Stem Seal

Valve Seat Machining Stock Calculation

Packaging of Valve Train System in Cylinder Head

Contact pattern between Roller Rocker Arm and Valve Tip

Valve Tip Height Variation

Valve train dynamics problems at Camshaft

Excessive wear on roller finger follower failed valve

train

Interface between Cam lobe and Roller Rocker Arm

Potential Effects of Failure Dimensional Objectives Identified


Cam – Crank max – min Position Error


Sign off Step 0

17


CoE Check 1 Activity

18


CoE Check 2

19


Coe Check 3

20


Chrysler PTVSA- Operation Model

21

Chief Engineer

Dimensional

Engineering Lead

Engines

Drive Line

/ Axles /

Trans

Engine

Systems

Adaptation

/ Vehicle

Integration

PLM / Data

Exchange

Project Lead

Domain

Experts

Process

Experts

Technologist

/ Modeling

Pro

gra

m m

anagem

ent

Pro

duct E

ngin

eers

Data Exchange

Chrysler Location Offsite Location


Chrysler PTVSA- Program Process

22

Identify PQC

Gage Design

Support

Document SOP/Learning

for Future Programs

Product Development Team

VSA Team

Legend

Program Timeline & Objectives

Mapping of VSA

Execution Plan to

Program Timeline

Provide Recomm-endations

Report VSA Program

Level Status

Finalize design/

tolerance changes

Change Release for

parts

Perform VSA

Mapping of VSA Execution Plan to Program Timeline

List of Objectives: • Fitment of Piston

Squirter • Spay Pattern Variation

Plot for Piston Squirter due to tolerances

Report VSA Program Level Status


Chrysler PTVSA- Execution Process

23

Function Objectives +Program Targets

Program Timing

Dimension Management Objectives Functionality Validation Component & subsystem fitment Sealing & leakage Prediction Packaging & Clearance Evaluations

Concept

VSA

Function Model & DFMEA

Drawings Objective Tracking Program Dashboard

Lau

nch

SEE WHAT YOU’RE MISSING U2U Conference - 24 -

Product Functionality Validation Compression Ratio calculation Crank to Cam Timing Front End Accessory Drive (FEAD) angle misalignment Stroke Determination (Lash Adjusters) Valve Rocker Contact Pattern Determination Sensor gap determination

Component & subsystem fitment All Engine component fitment e.g. Cylinder Head , All Covers , Oil Pan , etc.

Sealing & leakage Prediction RTV sealing land at component & assembly level. Bead Compression for Rear Seal Retainer (RSR). Determine compression for seals.

Field Failure & Special Purpose Analysis Root Cause for Field Failure (Dowel shearing issues) Machining Stock Determination Valve Cleanup Condition Crankshaft cast to machining stock determination Inventory Determination (tappet size determination) Front End Accessory Drive (FEAD) Belt length calculations. Incorporating manufacturing data.

Packaging & Clearance Evaluations Piston to valve clearance with dynamic position. Packaging evaluation with Assembly sequence impact All Engine components clearance with surrounding static & dynamic.

GDT AVS All Major Engine Component ‘s GDT validation and Tolerance Allocation

based on functionality and process. Tolerance Allocation based on VSA Study.

Top Level Objectives

VSA

Product Functionality Validation

Component & Subsystem Fitment

Packaging & Clearance Evaluation

Sealing & Leakage Evaluation

Field Failure & Special purpose

Consideration of Geometry effect.

Analysis based on magnitude of relevant parameters in system.

Pareto ranking of key characteristics to determine measurement plan.

Incorporation of process capability data.

What If Analysis to explore alternative design options.

Key Differentiators

GDT AVS (Allocation and Validation)

VSA – Objective Spectrum

24


Dimension Management : Project Traceability

25

Status Tracker

WO No system to trace

project throughout its

development stages

Dimension Management Scorecard / Dashboard

At Program level tracking of all objective.

Identification of all Performance / Fit / Sealing requirement

& tracking throughout Product development stages.


PTVSA : Tigershark 2.0L - Dashboard


Issue to be resolved

Key Issues - Tracker

27

Work Order Description Status Closure Date

453 Fitment of Fuel Rail with Intake Manifold. Interference of 0.349mm was observed between fuel rail hole and intake manifold dowel tab. GD&T on Intake Manifold needs to change to solve the issue. Required tolerance highlighted in the report.

15 Mar 2012

461 Update Required for acceptability of results projected by VSA Stacks for Flushness between Front Cover/Block/Cylinder Head/Oil Pan/Valve Cover.

472 RTV Sealing for Oil Pan. Lower limit of 2.5mm Violated. Update required if this is accepted by COC/Engineer.

482 Sealing Land Measurements observed to have high defect rates. Interference observed at T-Joint between Cylinder Head Gaskets and Timing Chain Cover. High defect rate observed for clearance between cylinder block and rivets on cylinder head gasket

488

Valve Cover Clearances less than design limit specified.

493

Volume Mismatch observed between Model (42.022 CC) and Drawing (42.83 CC). Need confirmation if failure rate is acceptable as it has a direct impact on Fuel Economy.

557 Sealing Edge from Valve Stem Seal enters into the chrome plated area of the valve which was a area of concern as per Ken. 19-Mar-2012

572 Fitment issues observed between Ac Compressor and Ladder Frame.

589 Thermostat Fitment Issue. Issue Currently Resolved.

593 Fitment Issues for Guide Timing Chain

628 Piston to Valve Clearance violates 1.5mm clearance limits. Clearance Reduced from previous study.

629 The ETC Surface crosses the boundary of the Intake Manifold sealing groove by 1.042mm. This indicates a possibility of leakages from the area. Requirement is the groove to always remain inside the sealing surface of ETC.

647 Fore-Aft Variation for Tigershark Pulleys greater that +/-0.5mm Limit.

691 Crank Sprocket to Camshaft Sprocket Alignment indicated the possibility of high thrust load as per Tom Edelmayer.

697 Fitment issue with Oil Jet Cooler Assembly.

721,

723,723,724

FEAD Clearance less than specified limits. Low Clearance conditions for Water Pump, Tensioner, Ac Compressor and Damper. Interference between AC Bracket and Oil Pan Assembly

738 NVH Brace Fitment Study

X Status Description :

Discussed Waiting for further updates

Closed Re-Analysis

X X

X

X

X

X


Engine systems Dimension Control

Simulation Analysis supports Exhaust systems right from conceptual design phase to post production phase by evaluating different objectives between these stages.

Variation Simulation Analysis- A predictive application for exhaust systems to avoid defects, improve cycle time, lower the costs, understand the process capability and control processes.

Variation Simulation Analysis- provides engineering direction for part or assembly development by validating GD&T and predicting the assembly joints behavior in exhaust systems.

GD&T and VSA

JS/JC

LX-3.0L(RHD/LHD)

CUSW PF 2.0L & 1.4L

DS-Gas

JK

WK/WD

JK

D-Series-DD/DP/DJ/D2

DS-Dsl

Completed Projects till Sept 2011 (Count 60)

GD&T and VSA

UF/UT-2.4L and 3.2L

KL-2.4L

KL-3.2L

DS-Gas

DS-DSl

Fuel SystemsVSA

6.4L Air Induction

D-Series-DD/DP/DJ/D2

3.0L Dsl Air Induction

Upcoming Projects-2012


Engine System Dimension Control Maturity va

lue

Support

Platform wise VSA Engagement

FY 2009 FY 2010

• Engine System Packaging & Functional Evaluation

•Engine System GD&T creation

•Engine System Gauging concept

•Field Failure or Plant Build Issue Evaluation

•Providing Design solution

Exhaust System Engineering

• Individual analysis Request based Work

• Fitment Analysis

•Subsystem clearance Analysis

FY 2012

•Involving in Joint definition

•Involvement in tooling kick off

•Involvement in Gauge review

• Feature functionality based VSA analysis

• Assembly Constraining- LX Dsl • Tooling kick off for LX & CUSW

• Tunnel to Hanger Clearance-Plant Issue • Tiger shark 2.0L Brace Fitment Analysis- Design Solution

• 2011 WK 3.6L Hot End Exhaust Steady Rest Bracket Fitment • Tiger Shark 2.0L Hot End Exhaust Fitment and sealing study


VSA for Solution-LT tip prominent

30

ASSEMBLY OVERVIEW

BODY FRAME EXHAUST

TAIL PIPE LH

EXHAUST TIP LH

EXHAUST TIP RH

EXHAUST TAIL PIPE RH

MUFFLER ASSEMBLY

EXTENSION PIPE EXHAUST PIPE ASSEMBLY

FRONT (Y-PIPE)

LOOSE FLANGES-NOT WELDED TO PIPES

VSA PROPOSAL 1 NORMA JOINT REMOVED

NORMA JOINT REMOVED

LOOSE FLANGES-NOT WELDED TO PIPES

VSA PROPOSAL 2

Problem Statement:

Cold End exhaust LT Tip more prominent as compared to RT tip

VSA Analysis output:

Design variation

Major contributors in system

Feature sensitivity

Design Recommendation

Advantages:

Number of parts reduced.

Number of Exhaust Joints reduced

Number of assembly operations reduced

Reduced tip variation.


Value Proposition: Reusability Concept

Power train variation for a particular Engine has been calculated separately & used as input for System level analysis across different platforms.

Re usability model

concept

5.7L 3.6L

1.4L 2.4L/2.0L

• Once a System level Model is created it can be reused to perform different tasks

– Evaluate different design proposals

• Different routing for clearance evaluation

• Various Joints (Exhaust System Joints) to understand system behavior

– Evaluate Supplier’s tolerance and Datum proposal

• Source Package tolerance and Datum evaluation

• Supplier’s feedback evaluation

– Evaluate different assembly concepts

• Torque sequence to negate assembly variations contributions

• Quick manufacturing data feedback by plugging data back into VSA model

Advantage:

• Reduction in Lead time

– Evaluation of different design configurations

– Gives decision making time on the basis of VSA

• Reduction in Execution effort (650 Hours of effort saved by implementing reusability concept till Sep-2011)


GDT allocation & Validation (AVS) GDT allocation & Validation work involves following major activities : Functionality tagging at feature level.

- Identification of functional / fit / assembly requirement of feature - Interrelationship among other feature - Relationship with Datum – Direct / Indirect compliance to Fit / Function.

Compliance to ASME / Company standards. - Datum Identification & Suitability. - Degree of Freedom (DOF) evaluation at feature level. - All relevant checks as per ASME standard - VCB Compatibility - Finalization of tolerance value (Component level or through Variation Simulation Analysis (VSA)).

Benchmarking against existing best practices. - For all possible cases checking with available company best practices - Input to designer with comparative details

Gauging & Manufacturability of Feature. - Cross verification of functional requirements with manufacturing sequence / feasibility. - Interaction with Chrysler Vendors as required for component gauging (Engine Systems).


Case Study : GDT AVS

Input Desired Output

Detailed Feature Level Breakup

ASME Compliance

Identification of Issue

Markup on Drawing to trace

Features Recommendation on GDT

Justification with proposed change


Thank You

Documents

Assembly Variation Analysis Objective Development for