Method Development & Fluid Performance in the Machining of 4140 Steel

ARIE GARZON, NAZERKEM ITYBAYEVA, RICHARD MASTRORILLI

Project Scope

PROBLEM DESCRIPTION & PROJECT REQUIREMENTS

Problem DescriptionThe focus of the project is to develop a testing method to determine the quality of a machining coolant

Three fluids provided to test:◦ Quakercool 750-TP

◦ Quakercool 2776

◦ Quakercool SH-720

Project RequirementsUse the experiment to test the quality of three different coolants.

Correctly identify the good quality fluids from the poor quality fluids

Test needs to have the ability to be duplicated by Quaker’s lab testing facilities.

Thread cutting must be performed using a vertical CNC, not a horizontal turning machine

Project Solution & Procedures

METHODS, MACHINING, AND ANALYSIS PROCESS

FluidsFluid mixed would be to a 10% concentration as specified by Quaker

Hardness of 125 ppm also specified and was achieved by mixing 50% distilled water with 250 ppm tap water

Concentrations would be verified by using a refractometer

Project SolutionA tapping procedure was selected

Torsional force data recorded using a dynamometer

A go/no-go gage used to verify quality

Average torsional force at each interval would be calculated

Project SolutionThe data can be regressed to find a potential linear relationship

The hope is that the linear relationship leads to rate of tool wear

A difference of mean test will then be used to statistically determine the significance of data

Null hypotheses states difference of mean between samples is equal to 0; (x1 – x2 = 0)

ProcedureThe machine selected is a HAAS VF 2-SS

Test consists of two blocks 4140 steel blocks

One 4”x4” steel block is attached to a dynamometer

A larger block 4”x8” is held by a table vice

ProcedureThe process first machines 12 holes in the small block using the machining process (listed on next slide)

36 holes are then machined into the larger block

Machining ProcessSpot Drill to 14mm diameter at a speed of 485 rpm and a feed of 4.2 ipm

Peck Drill through 9.8mm diameter at a speed of 693 rpm and a feed of 6.0 ipm

Ream through to 10.2mm diameter at a speed of 285 rpm and a feed of 5.1 ipm

ProcessA TiCN Plug Tap M12x1.75 is used for the tapping procedure

Tapping is performed to a depth of 1 inch at a speed of 242 rpm and a feed of 16.7 in/min

Three holes are first tapped in the larger block

ProcessA hole is then tapped in the smaller block

Force and moment data is recorded through the dynamometer each time a hole is tapped in the small block

A full test is comprised of 12 cycles (48 holes)

Each test yields 12 sets of torque data

The test is performed twice for each fluid

Each test utilizes a new tap

Results

DATA REGRESSION AND STATISTICAL SIGNIFICANCE

Data Analysis- Coolant 1Regression of average torsional values of QC 750-TP

P-value of .032

R-Sq value of 38.3%

50403020100

105

100

95

90

85

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S 5.69291

R-Sq 38.3%

R-Sq(adj) 32.2%

Trial

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Fitted Line PlotCoolant 1 = 81.49 + 0.2968 Trial

50403020100

105

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95

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S 7.04671

R-Sq 16.0%

R-Sq(adj) 7.6%

Trial

Co

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Fitted Line PlotCoolant 2 = 87.96 + 0.2033 Trial

Data Analysis- Coolant 2Regression of average torsional values of Quakercool 2776

P-value of .198

R-Sq value of 16%

Data Analysis- Coolant 3Regression of average torsional values of Quakercool SH-720

P-value of .304

R-Sq value of 10.5%

50403020100

100

95

90

85

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S 6.57234

R-Sq 10.5%

R-Sq(adj) 1.6%

Trial

Co

ola

nt

3

Fitted Line PlotCoolant 3 = 90.28 - 0.1490 Trial

Data Analysis

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4 8 12 16 20 24 28 32 36 40 44 48

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Trial

Average Torsional Tapping Forces

QC 750-TP Quakercool 2776 Quakercool SH-720

Data AnalysisFirst t-test (coolant 1 and 2):

QC 750-TP and QC 2776; 95% CI (-10.09, 2.01); P-value .18

Fail to reject null hypothesis

Second t-test (coolant 1 and 3):

QC 750-TP and QC SH-720; 95% CI (-2.94, 8.55); P-value .32

Fail to reject null hypothesis

Third t-test (coolant 2 and 3):

QC 2776 and QC SH-720; 95% CI (.91, 12.78); P-value .026

Reject the null hypothesis

Interpreting the resultsThe only statistically significant difference in mean is between QC 2776 and QC SH-720

The only coolant that has a significant chance of being represented by a linear relationship would be QC 750-TP due to its p-value of .032, R-Sq value of 38.3%, and visual inspection

Future development of the experiment:

Lack of tool wear is believed to have caused an overall lack of linear trends

Finding end of life of the taps will shed more light on the trend of torsional force as the tool wears