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Performance Studies

Acoustech-Product-on-Whiite-wShadow-3840x2160Acoustech Systems has demonstrated the ability to offer significant improvements to machining processes through a reduction in cutting forces.

In addition to the benefits with tool life and microstructural behavior, reducing force also allows manufacturers the ability to significantly increase feed rates. In many cases, these increased feed rates continue to operate well below the conventional machining forces. Lastly, surface finish and tolerances can be held to a higher standard as the tool is subjected to lower forces, decreasing tool deflection and tool position issues.

Approach

Characterization tests were carried out with Acoustech System’s machining module using industry standard tool holders and off-the-shelf tooling. The test was set up to use recommended feeds and speeds provided by the tool manufacturer and then assess the forces resulting from the machining process using a Kistler 9272 dual channel dynamometer. Feed rates were then increased in an attempt to arrive at the conventional forces. Samples of these tests were inspected using a Zeiss profilometer. Cross sections were then cut to evaluate changes in microstructure.

Results

The tables that follow represent data collected when comparing conventional drilling conditions against those utilizing the Acoustech Systems product. Although the feeds and speeds can arguably be improved based on machine and tooling, the impetus of this test is to show a reduction in applied force at the same feeds and speeds, but also how more aggressive chip loads maintain lower forces than conventional parameters. As noted, the surface finish remains the same, if not better, and dimensional stability is unchanged.

The Acoustech Systems product not only showed a reduction in applied force at the same feeds and speeds, but also that more aggressive chip loads maintain lower forces than conventional.

Changes in microstructure and potential damage to the surface were evaluated by sectioning various samples from the test matrix. Each specimen was mounted and polished, followed up with micrographs of the hole’s edge profile. The following images represent the drilled condition of each series of parameters.

Performance Study of 316 SS

316 Stainless Steel is known for poor chip formation and breakage, which leads to long chips – often entangled around the work piece or cutting tool.  Other complications include work hardening while machining and poor tool life.  The purpose of this test was to assess cutting forces when applying ultrasonic vibrations.  The key takeaway from this test is that forces can be reduced in a manner in which chip loads can be increased without exerting more force and sacrificing tool life.  Most importantly, neither surface finish quality nor dimensional accuracy was sacrificed.

Performanc Study of 316 SS

Performance Study of 4340 Steel

4340 alloy steel is relatively common and easily machined steel.  This evaluation is purely focused on the level of force reduction made possible by applying ultrasonic energy to the drilling process and how much it can be pushed until the resulting forces were obtained.  Once again, neither surface finish nor dimensional stability were sacrificed even though chip loads were increased significantly.  The takeaway of this evaluation is the feed rates can be increased without sacrificing quality – even on a common machined material.

Performance-Study-of-4340-Steel

Performance Study of 6061-T6 Aluminum

Traditionally, 6061-T6 aluminum is not thought of as a difficult to machine material.  However, if we look at this material with respect to machine capability, we can see from the data provided in the following tables that force can be reduced by as much as 60%.  This in turn directly relates to tool life but also the size of equipment that must be sized for an application.  One of the benefits offered with ultrasonic machining is the excitation of the tool flutes which tend to act as a self-feeding chip extractor.  In essence, ultrasonics acts as a vibratory feeder bowl helping to push chips up the flutes in deep drilling applications.

Performance Study of 6061 T6 Aluminum

Performance Study of Titanium 6Al-4V

Titanium is a well-known, difficult to machine material – especially in the aerospace market.  The significance of this test is the ability to again demonstrate increased feed rates while maintaining surface finish and dimensional stability.  However, it is important to highlight one of the most critical aspects in dealing with titanium.

Looking at the cross section in Figure 1, it is clear that an alpha case transformation (white layer) has occurred from the heat generated during the drilling process.  When this is compared to the conventional parameters with ultrasonic energy and also those using higher feed rates with ultrasonics, alpha case is eliminated or significantly reduced at high feed rates.  This is difficult to obtain under some of the most stringent drilling operations.

 

Performance Study of Titanium 6Al 4V