Fluid Performance in Turning of Aluminum Alloys

Overview

Quaker Houghton is a global leader in primary and metalworking industrial process fluids. They develop cutting fluids that benefit many different machining processes. Proper cutting fluids are able to cool and lubricate machining regions as well as flush away the chips produced. These fluids help to improve surface quality of the machined part, and help decrease tool wear rate. Quaker is concerned with the surface finish of aluminum alloy wheels. Wheels are machined on a CNC turning center.

Objectives

The major objectives of the project were:

1- Developing a standardized turning experiment for assessing the performance of three cutting fluids.

2- Using this turning experiment to evaluate the three fluids based on tool wear rate, machined surface appearance, surface roughness below 8 microinch, and the presence of deposited metal. Built up edge and flank wear on the insert was analyzed using digital microscopy. SEM analysis was also used to analyze cutting edge wear and any Al build up.

Approach

The team conducted a series of six tests on the given billets using the Haas SL-30 CNC Lathe with three different cutting fluids and two inserts. Testing Conditions: Cutting speed: 500 m/min, Feed rate: 0.04 mm/rev, and Depth of cut: 0.1 mm
A series of 10 passes were performed before observing the billet. The team visually inspected the billet appearance for failure as well as took surface roughness values. The team also took digital images of the inserts and measured the wear using a Mitutoyo Stereoscope every 20 passes. The passes were completed until the team noticed a failure such as scratching or consistent surface roughness over 8 microinches.

Outcomes

Figure 1 overviews the amount of passes conducted before scratching was noticed on the inserts, which was the first failure mode detected in all the experiments. Figure 2 shows the average Ra values for all fluids in three different sides of the billet. The Hocut 7661 PCD test was not conducted due to a joint decision from the Penn State team and Quaker Houghton team due to limited time and wanting to run the Hocut 7661 carbide test until failure instead of when the discontinuous sections were machined away. Additionally, a second billet had to be used to achieve failure for the Hocut 7661 carbide and thus there were no remaining billets to conduct the PCD Hocut 7661 test. The best fluid was determined through the carbide tests; the Hocut 7661 carbide test lasted much longer than the CM-43 and QC 2920-EVC fluids and thus was the optimal fluid found through experimentation. This was the decision presented to Quaker Houghton and agreed upon with them.