Rotary Ultrasonic Machining Technology(RUM) vs. Conventional Ultrasonic Machining Technology (UM)

1. Brief Introduction of Conventional Ultrasonic Machining Technology
Rotary Ultrasonic Machining (RUM) is regarded as an enhancement of UM. The basic principle is the combination of conventional UM and CNC grinding/milling process. The difference between RUM and UM is the vibrating object. With high frequency micro vibrations, UM applies in vibrating the abrasive slurry and make the particles remove the materials. The uncontrollability of liquid and the limitation of tools and equipment restrict the further applications of UM.
 
Rotary ultrasonic machining technology superimposes rotational movement with 20k-40k high frequency vibrations of Z-axis direction. The rotating diamond coated tooltip will directly abrade the materials to tiny particles and they will be carried away by coolant. RUM changes continuous cutting to intermittent movement via low amplitude micro-oscillations; therefore, the tool load and the thermal impact could be significantly reduced. Additionally, by side and vertical directions of feed exercised simultaneously, the material remove rate could be enlarged
 

USM is poised to high precision and ununiform machining. Also, it is a great substitution for EDM (Electrical Discharge Machining) to materials which are extreme hard, brittle, and non-conductive. It contains transducer, sonotrode (also named as horn), tool of desired shape, and a tank of water-based abrasive slurry. The grains in the slurry are usually composed by boron carbide and silicon carbide, which are of high rigidity. The tool and the materials that required to process will both sink in the slurry. As the micro-vibrations of low amplitude (25-100 microns) and high frequency (15-30 kHz) transmitting by transducer to tooltip, these grains in the slurry will be driven to strike the workpiece and the materials will gradually abord till matching the shape of tool. The tool and the material will not contact each other so that there is no thermal impact will be generated.

However, the disadvantages of UM are obvious. UM can only deal with materials at least hardness 45 HRC. Soft material has less material removal and tends to absorb particles. Besides, the movement of slurry is hard to control to the depth, USM is not capable of deep hole drilling.
And the material removal rate is much slower than other machining solutions with uncontrollable movement. These could be challenges to mass production. And the collision between tools and grains lead to severe tool wear.

Referred from Wikipedia: https://en.wikipedia.org/wiki/Ultrasonic_machining

2. Enhancement of Rotary Ultrasonic Machining (RUM) from Ultrasonic Machining (UM)
Rotary Ultrasonic Machining (RUM) is regarded as an enhancement of UM. The basic principle is the combination of conventional UM and CNC grinding/milling process. The difference between RUM and UM is the vibrating object. With high frequency micro-vibrations, UM applies in vibrating the abrasive slurry and makes the particles remove the materials. The uncontrollability of liquid and the limitation of tools and equipment restrict the further applications of UM.
 
Rotary ultrasonic machining technology superimposes rotational movement with 20k-40k high frequency vibrations of Z-axis direction. The rotating diamond-coated tooltip will directly abrade the materials to tiny particles and they will be carried away by coolant. RUM changes continuous cutting to intermittent movement via low amplitude micro-oscillations; therefore, the tool load and the thermal impact could be significantly reduced. Additionally, by side and vertical directions of feed exercised simultaneously, the material remove rate could be enlarged.

3. Rotary Ultrasonic Machining Technology (RUM) Application on advanced materials.

RUM maintains the advances and fixes the drawbacks of USM. Without the limitation of slurry, tools, and materials, RUM could apply on various hard to cut materials includes ceramic, quartz, and sapphire, and features with current CNC machining procedure.
Deep hole drilling, Micro-features, and thin-wall machining with high precision are suitable to RUM since the intermittent vibrations could reduce cutting resistance and prevent edge-crack.
Apart from well-known application of RUM in hard and brittle materials,
the vibrations could also prevent materials jamming or binding on the tool, which presents potential on thermoplastic CFRP and stainless steel.
RUM is also considered a non-thermal solution and available for hard metal such as tungsten carbide and Inconel to enhance machining performance with the least thermal impact.

Click for more info:
*More RUM applications
*RUM great for technical ceramic machining
*Brief introduction of ceramic substrates and how can HIT ultrasonic machining conquer the machining difficulties

4. RUM technology Enhancement in HIT Ultrasonic Machining Module
RUM technology often integrates in spindle type or a special spec. of machine, which is costing and time-consuming while introducing.
HIT Ultrasonic Machining Module has combined RUM technology and module design for flexible installation on current CNC equipment. The improvement breaks the assumption and hesitation of introducing a new technology, manufacturers could use RUM function to grid, drill, and mill and achieve performances by side add-on our module.