VSR EQUIPMENT COMPARISON
Here are some fundamental comparisons between the three most popular vibration systems available:
INDEPENDENT RESEARCH AGREES:
All the independent research work states that both resonance and sub-resonance can be effective, but that:
RESONANCE WORKS BETTER
. . . . either gauged on how much stress is relieved, or how long it takes to relieve stress (i.e., resonance is faster). The EPA has also weighed in on this issue, stating clearly that resonance is the most effective means of stress relief : EPA link
These works can be seen in the Advanced VSR Technical Library:
- Dr. William Hahn, Vibratory Residual Stress Relief and Modifications in Materials to Conserve Resources and Prevent Pollution
- Dr. S. Shankar, Vibratory Stress Relief of Mild Steel Weldments
- Drs. Y. P. Yang, G. Jung, and R. Yancey Finite Element Modeling Of Vibration Stress Relief After Welding
Bonal console has 6.5" touchscreen (similar to automotive / back-of-seat video monitor) mounted in NEMA 1 (nominal protection from dust or moisture) grade enclosure.
Advanced VSR Console's display is FOUR TIMES LARGER, making it easier for the operator to see critical data.
A-VSR Model 7.5 Console is NEMA 4 / IP 65 enclosed (no dust, dirt or sprayed water entry), features 15" / 380 mm touchscreen industrial PC with solid state HD. Uses Allen-Bradley 3 HP / 2.2 kW drive with external heat sink (waste heat exits outside of enclosure). Motor temperature reported on VSR OS Main Screen (bargraph at top / middle). VSR charts, tagged with PN and SN of workpiece, are archived in PDF format, with user-friendly software. Lid closes for full protection during storage.
Advanced VSR MS9 vibrator is AC powered, and features variable unbalance over a 20:1 range, a max speed of 9000 RPM, and a 1.2 kW motor designed to operate continuously . Unbalance adjustment takes one minute, using standard hex keys. Sensors in motor windings supply temperature data to console. Hardened inserts in feet assure good clamping quality. Through holes in feet can be used for bolts, ideal for fixtured applications, or when using an adapter plate.
Advanced VSR only uses industrial-grade vibrator cable connectors with die-cast aluminum housings and coiled spring strain reliefs, mounted on fully shielded servo-grade cable. Vibrator socket located on right front of operating panel, within easy reach of the operator.
Bonal uses a soft-plastic housed vibrator cord connector. On this two year unit the affixing collar threads were stripped. SO-grade electrical cable. Clamp collar is the only strain relief. Connector on back of unit, outside immediate reach of operator. Note circuit breakers on back of unit, for mains, motor field and armature. This is protection against short-circuiting, not motor protection (overload or over-temperature).
Force vs. speed / RPM of both the Advanced VSR and Bonal vibrators. Both units have adjustable unbalance, but the A-VSR unit has the twice the available unbalance, plus 3000 more RPM. Workpieces that have resonances above Bonal's 6000 RPM limit (imposed by their brushed motor design) could not receive effective stress relief.
Closeup of the surface motor brushes ride upon, called a "commutator". These can suffer overheating and rupture, such as the one shown, if a combination of heat and mechanical loading, including vibration, lasts too long. Also, esp. if vibrated, the carbon brushes produce a cloud of carbon dust that clings to the motor interior, leading to shorts / faults. It is for this reason that Advanced VSR abandoned brushed motors for AC and DC brushless motors roughly twenty years ago. DC brushed motors and the drives that power them remain the cheapest form of variable speed, but their reliability for high-speed apps is questionable.
Also, a brushed motor has less speed / RPM range than a brushless motor, which is apparent from the chart on the upper right.
In the VSR Chart above, peak growth of ~ 30 percent can be seen (red peak above original green peak), with almost no peak shifting. This poses an interesting question:
If an operator was monitoring treatment progress while tuned off the peak (i.e., subresonance) how could he tell when he was finished ?