INTELLIGENT MACHINING & PROCESS CONTROL :

Cost optimization in machining

• Tool wear monitoring• Practical tool wear metrology

• Continuous optimization

• Process stability monitoring • Acoustic and vibration monitoring

• LabVIEW based signal processing

Sponsor: General Dynamics - OTSCoach: Dr. Tim DalrympleLiaison Engineer: Mr. Keith Brown

William Dressel (ISE)Kevin Pham (EE)Steven Stone (CSC)Sean Sullivan (ME)Phan Vu (ME)

Team:

MACHINELOGIC

Pipe Coupling

Minimize work piece costDetermine tool cost

○ Monitor wear and end of life○ Implement practical metrology

Determine machining costBalance the process to minimize cost

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Project Goals & Objectives MACHINELOGIC

Project Goals & Objectives

Provide feedback to digital manufacturing frameworkDevelop data acquisition systemAutomate data and error loggingMonitor machine stability: chatter

detection

MACHINELOGIC

Minimizing Work Piece CostCp = Cfix + Cm + Ct

Cp = Cost per part

Cfix = Fixed cost associated with the cost of the material

Cm = Machining cost

Ct = Tooling cost related to tool life and tool change time

T = C (v)p (fr)q

T = Tool life

v = Cutting speed

fr = Feed rate

C, p, and q = Constants

MACHINELOGIC

Minimizing Cost ProcedureRearrange Cost per part equation:

Take partial derivatives:

Optimal cutting speed:

𝐶𝑝𝑎𝑟𝑡 = 𝑐𝑓𝑖𝑥𝑒𝑑 +ሺ𝜋𝐷𝑚𝐿ሻቆ𝑟𝑚𝑣𝑓𝑟+ 𝑡𝑐ℎ𝑟𝑚 +𝐶𝑡𝑒𝐶𝑣−𝑝+1𝑓𝑟−𝑞+1ቇ

𝜕𝐶𝑝𝑎𝑟𝑡𝜕𝑣 = ሺ𝜋𝐷𝑚𝐿ሻቈ− 𝑟𝑚𝑣2𝑓𝑟+𝑡𝑐ℎ𝑟𝑚 +𝐶𝑡𝑒𝐶𝑓𝑟−𝑞+1 ሺ𝑝−1ሻ𝑣𝑝−2 = 0

𝜕𝐶𝑝𝑎𝑟𝑡𝜕𝑓𝑟 = ሺ𝜋𝐷𝑚𝐿ሻ− 𝑟𝑚𝑣𝑓𝑟2+𝑡𝑐ℎ𝑟𝑚 +𝐶𝑡𝑒𝐶𝑣−𝑝+1 ሺ𝑞−1ሻ𝑓𝑟𝑞−2൨= 0

𝑣𝑜𝑝𝑡 =ቈ𝐶𝑟𝑚

ሺ𝑝−1ሻሺ𝑡𝑐ℎ𝑟𝑚 +𝐶𝑡𝑒ሻ𝑓𝑚𝑎𝑥𝑞 1/𝑝

MACHINELOGIC

Determining Tool Life Through Flank Wear Width

Microscope: Dino-Lite® Wyko Profilometer

Device Cost: $400

Device Cost: $180,000

MACHINELOGIC

Tool Wear Analysis Results

MACHINELOGIC

Calculating Optimum Machining Parameters

Nominal Cutting Speed

Nominal Feed Rate

6338 in/min

.02 in/rev

Suggested Cutting Speed

Suggested FeedRate

6972 in/min(~110%)

.02 in/rev

Optimal Cutting Speed

Optimal Feed Rate

9066 in/min

.02 in/rev

Nominal SuggestedOptimal

MACHINELOGIC

Machining Controller Solution INPUT SYSTEM OUTPUT

Human Machine Interface

Data Acquisition System

Computer

LabVIEW

Analyze Data

Human Machine Interface

Log Data

MACHINELOGIC

Power

Vibration

Audio

OKUMA LC-40 Lathe

Load Controls UPC

CM100 Microphone Kistler Accelerometer

MACHINELOGIC

Prototype GUIMACHINELOGIC

Chatter Detection: Variance

MACHINELOGIC

Chatter Detection: FFT

Model boring bar as fixed-pinned cylinder Calculate natural frequency 1st mode = 3047 Hz Sample signal at 10 kHz Nyquist frequency of 5 kHz

𝝎𝒏= 𝜷𝟐𝟐𝝅ඨ 𝑬𝑰𝝆𝑨𝒄𝑳𝟒

MACHINELOGIC

Chatter Detection: FFTMACHINELOGIC

Signal Process Analog Filtering

Blue – Sampled Frequency Red - Aliased Frequencies

MACHINELOGIC

Sallen-Key Gain in passband: 1

Gain at cutoff (7kHz): 1/2

Design & Test: Low Pass Filter

MACHINELOGIC

Low Pass Filter ResultsMACHINELOGIC

Initial Investment

Cost Per Unit

Units Ordered

Total Investment

Cost Saved

Per Part

Parts Produced Per Shift1

Parts Produced Per Year2

Cost Saved

Per Year2 R.o.I.

Prototype Investment

$20,000 $12,808 1 $32,808 $0.29 56 13,351 $3,894 11.9%

Industry Level Investment

$106,000 $8,893 6 $159,358 $0.29 340 80,110 $23,36514.7%

1 Based on 10 hour shift2 Based on one shift per day, 235 work days per year

Initial Investment

Cost Per Unit

Units Ordered

Total Investment

Cost Saved

Per Part

Parts Produced Per Shift1

Parts Produced Per Year2

Cost Saved

Per Year2 R.o.I.

Prototype Investment

$20,000 $12,808 1 $32,808 $0.29 58 13,749 $9,36228.5%

Industry Level Investment

$106,000 $8,893 6 $159,358 $0.29 351 82,494 $56,17335.2%

Roughing Operations Optimized with Suggested Machining Parameters

All Operations Optimized

Return on InvestmentMACHINELOGIC

Initial Investment

Cost Per Unit

Units Ordered

Total Investment

Cost Saved

Per Part

Parts Produced Per Shift1

Parts Produced Per Year2

Cost Saved

Per Year2 R.o.I.

Prototype Investment

$20,000 $12,808 1 $32,808 $0.29 56 13,351 $3,894 11.9%

Industry Level Investment

$106,000 $8,893 6 $159,358 $0.29 340 80,110 $23,36514.7%

1 Based on 10 hour shift2 Based on one shift per day, 235 work days per year

Initial Investment

Cost Per Unit

Units Ordered

Total Investment

Cost Saved

Per Part

Parts Produced Per Shift1

Parts Produced Per Year2

Cost Saved

Per Year2 R.o.I.

Prototype Investment

$20,000 $12,808 1 $32,808 $0.29 58 13,749 $9,36228.5%

Industry Level Investment

$106,000 $8,893 6 $159,358 $0.29 351 82,494 $56,17335.2%

Roughing Operations Optimized with Suggested Machining Parameters

All Operations Optimized

Return on InvestmentMACHINELOGIC

Initial Investment

Cost Per Unit

Units Ordered

Total Investment

Cost Saved

Per Part

Parts Produced Per Shift1

Parts Produced Per Year2

Cost Saved

Per Year2 R.o.I.

Prototype Investment

$20,000 $12,808 1 $32,808 $0.29 56 13,351 $3,894 11.9%

Industry Level Investment

$106,000 $8,893 6 $159,358 $0.29 340 80,110 $23,36514.7%

1 Based on 10 hour shift2 Based on one shift per day, 235 work days per year

Initial Investment

Cost Per Unit

Units Ordered

Total Investment

Cost Saved

Per Part

Parts Produced Per Shift1

Parts Produced Per Year2

Cost Saved

Per Year2 R.o.I.

Prototype Investment

$20,000 $12,808 1 $32,808 $0.29 58 13,749 $9,36228.5%

Industry Level Investment

$106,000 $8,893 6 $159,358 $0.29 351 82,494 $56,17335.2%

Roughing Operations Optimized with Suggested Machining Parameters

All Operations Optimized

Return on InvestmentMACHINELOGIC

Conclusion

Cost savings achieved through higher cutting speeds

Limited by stability issuesData acquisition system can help address

stability issuesAcoustic data more suitable for detecting

chatter

MACHINELOGIC

Recommendations for Future Develop alternative for LabVIEW Store logged data in database Automatically handle chatter through

lathe control panel Continue tool wear analysis

Automate tool wear measuring process Continue power data analysis

MACHINELOGIC

Questions?

Special Thanks to:

IPPD Program General Dynamics Dr. Dean Bartles Dr. Keith Stanfill Mr. Keith Brown Dr. Tim Dalrymple Dr. John Schueller Mr. Gun Lee