1 Introduction
2 Material and methods
2.1 Laboratory tests
2.2 Tribological experiments
2.2.1 Brugger tests
2.2.2 Tapping-torque tests
2.3 Experiments on machine level
2.3.1 Machining process chain
Drilling | Chamfering | Thread forming | |
---|---|---|---|
Tool material | Solid carbide | HSS-E | HSS-E |
Tool coating | Diamond-like carbon | Titanium aluminium nitride | Titanium nitride |
Tool standard | DIN 6537 | Manufacturer-specific | DIN 2174 |
Depth | 32 mm | 0.3 mm | 30 mm |
Diameter | 5.55 mm | 45° | M6 |
Feedrate | 0.25 mm/R | ||
Cutting speed | 120 m/s | ||
Tolerance | h7 | ||
MWF supply | Internal plus external nozzle | External | External |
2.3.2 Machining tests
2.4 Control of operations-related emissions
2.4.1 Screening of nonpolar to polar volatile compounds
Gaschromatograph | GC 7890B, Agilent Technologies (Santa Clara, CA, USA) |
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Mass selective detector | 5977A MSD, Agilent Technologies (Santa Clara, CA, USA) |
Chromatographic column | DB-1301, 60 m, inner diameter: 0.32 mm, film thickness: 1 µm, Agilent Technologies (Santa Clara, CA, USA) |
Carrier gas | He, 1 mL/min |
Injection mode | Splitless |
Injection volume | 1 µL |
Temperature program | 50 °C, 2 min, 10 °C/min to 280 °C, 15 min |
Measuring mode | EI: 70 eV, full-scan-mode, m/z: 45–600 |
2.4.2 Determination of volatile carbonyl compounds
Instrument | HPLC Series 1260 Infinity, autosampler, diode-array-detector, Agilent Technologies (Santa Clara, CA, USA) |
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Chromatographic column | Pursuit XRs 5 C18, 250 × 4.6 mm, 5 µm, Agilent Technologies (Santa Clara, CA, USA) |
Column temperature | 40 °C |
Eluent | Eluent A: water/acetonitrile (40/60; v/v) Eluent B: acetonitrile |
Gradient | Time (min) B (%) 0, 0 5, 0 20, 100 |
Flow rate | 1.5 mL/min |
Injection volume | 10 µL |
Detection wavelength | 360 nm |
3 Results and discussion
3.1 Chemical development of the novel metal working fluids for aluminium machining
Component | Concentration (mass-%) | Function |
---|---|---|
Water | 44.43 | Base fluid, cooling effect |
Glycerol | 45.60 | Lubricity enhancement, thickening agent, preventing microbial attack |
Alkanoic acids | 3.00 | Lubricity enhancement |
Amine compounds | 4.00 | Neutralization, pH value adjustment, corrosion protection, complexing agent |
Polyglycol ethers | 2.80 | Lubricity enhancement, defoamer |
Ether | 0.15 | Defoamer |
Triazole derivative | 0.02 | Non-ferrous metal inhibitor |
Compound | Concentration (mass-%) | Function |
---|---|---|
Water | 45.64 | base fluid, cooling effect |
1,3-Propanediol | 22.50 | lubricity enhancement, thickening agent, preventing microbial attack |
Polyglycol ethers | 12.50 | lubricity enhancement, defoamer |
Alkanoic acids | 12.50 | lubricity enhancement |
Amine compounds | 6.80 | neutralization, pH value adjustment, corrosion protection, complexing agent |
Ether | 0.04 | defoamer |
Triazole derivative | 0.02 | non-ferrous metal inhibitor |
3.2 Tribological experiments
Metalworking fluid | Tapping-torque test | Brugger test | |
---|---|---|---|
ΔT (°C) | Mzmax (Ncm) | B (N/mm2) | |
Alloy EN AW-6060 | |||
Reference fluid | 2.7 | 70.0 | 33.9 |
Glycerol MWF | 1.5 | 65.0 | 19.3 |
Propanediol MWF | 1.3 | 50.0 | 23.8 |
Alloy EN AW-7075 | |||
Reference fluid | 5.9 | 135.0 | 28.7 |
Glycerol MWF | 4.4 | 141.7 | 24.3 |
Propanediol MWF | 5.1 | 111.7 | 27.8 |
3.3 Experiments on machine level
3.3.1 Drilling
3.3.2 Thread forming
3.4 Analytical monitoring of airborne pollutants emitted from the MWF formulations in use
Compound | Max. air pollution at the machine (mg/m3) | Occupational limit value according to TRGS 900 (mg/m3) | Undercutting factor |
---|---|---|---|
Acetaldehyde | 0.084 | 91 | 1083 |
Acetone | 1.5 | 1200 | 800 |
Butyraldehyde | 0.071 | 64 | 901 |