CFEST Case Study/Demonstration
This case study demonstrates how to use the CFEST program to help make decisions regarding the selection of cutting fluid type and fluid application strategy. To run CFEST, the following data need to be provided to the program:
- Machining Process Data
- Tooling Data
- Cutting Fluid Data
- Fluid System Data
- Fluid Treatment Data
- Health Hazard Data
- Site Specific Data
The scenario for this case study is: A manufacturer needs to choose a cutting fluid and application strategy for a turning operation. The types of fluid to be considered are 3% synthetic oil and 10% soluble oil fluid. Application method can be jet or flood.
Other data for the hypothetical situation is:
- Workpiece Material: Gray Cast Iron
- Workpiece Diameter: 100 mm
- Workpiece Length: 300 mm
- Cutting Tool Material: Tic Cemented Carbide
- Spindle Speed: 1000 rpm
- Feed Rate: 0.2 mm/revolution
- Depth of Cut: 2 mm
- Cutting Fluid Flow Rate in Jet Application: 10 liters/min
- Diameter of Nozzle: 8 mm
- Position of Nozzel: 80 mm above Workpiece
- Cutting Fluid Flow Rate in Flood Application: 30 liters/min
- Fluid System Capacity: 2000 Gallons
- Direct Labor for Fluid System Maintenance: 1 worker
- Labor Cost: $9.00/hour
- Cost of Additive: $100.00/week
- Energy Cost: $100.00/week
- Sewer Discharge Rate: 700 gallons/week
- Makeup Concentrate Added for 10% Soluble Oil System: 70 gallons/week
- Makeup Concentrate Added for 3% Synthetic Oil System: 21 gallons/week
Any data not given here is assumed to be the default input in CFEST program.
In order to make a decision regarding which fluid and which application method is better for this operation, the CFEST program needs to be run four times with different combination of inputs considering the two fluid types and the two application strategies. With the above input data, the following results of fluid performance, cost and environmental impact can be obtained:
Fluid Type |
10% Soluble Oil |
3% Synthetic Oil |
Application Method |
Flood |
Jet |
Flood |
Jet |
Procurement Cost ($) |
730.00 |
730.00 |
900.00 |
900.00 |
Maintenance Cost ($/month) |
764.50 |
764.50 |
824.00 |
824.00 |
Heat Transfer Coefficient (W/(Square meter*K)) |
9816 |
21430 |
10463 |
23117 |
Fluid Heat Transfer Rate (W) |
619 |
140 |
644 |
150 |
Mean Mist Size (micron) |
6.72 |
4.73 |
6.89 |
4.85 |
BOD Cost ($/week) |
5.84 |
5.84 |
0.35 |
0.35 |
FOG Cost ($/week) |
43.78 |
43.78 |
2.63 |
2.63 |
Nitrate Cost ($/week) |
0.12 |
0.12 |
0.02 |
0.02 |
Phosphate Cost ($/week) |
0.06 |
0.06 |
0.01 |
0.01 |
The health hazard scores depend on cutting fluid constituents and the site specific factors, which may vary from one facility to another. The above results indicate that the flood application results in better heat transfer performance as compared to the jet application method, but the maintenance cost for the jet application method is less. When the two alternative fluid types are considered, it can be seen that 3% synthetic oil gives comparable process performance, but results in less fluid treatment cost. However, the cost of procurement and fluid system maintenance is higher than for 10% soluble oil fluid. These quantitative results help CFEST users to evaluate and different fluid types and application methods and select the one that is best for the operation.
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