Calculating Applied Media Force during Vibratory Finishing
What appear to be identically set-up vibratory bowls will finish identical loads of parts in varying time cycles. This paper offers a new technique to better predict what the operator will produce, by measuring the force applied to the parts. It is the efficiency of that force which controls the efficiency and speed of the refinement cycle.
William P. Nebiolo*
REM Chemicals, Inc.
Southington, Connecticut, USA
Editor’s Note: This paper is a peer-reviewed and edited version of a presentation delivered at NASF SUR/FIN 2016 in Las Vegas, Nevada on June 6, 2016. A printable PDF version is available by clicking HERE.
Despite conscientious attempts to equilibrate vibratory variables such as bowl amplitude, roll angle, media species, media volume, part loading, process liquid concentration and flow rate, what appear to be identically set-up vibratory bowls will nonetheless finish identical loads of parts in varying time cycles. Why is this so? This paper will explore this phenomenon. Techniques will be introduced that will allow operators to capture operational characteristics that aren't typically apparent. A formula will then be introduced that will allow operators to apply this new data to calculate the amount of force that the media is actually applying to the parts. It is the efficiency of the force applied to the parts during vibratory finishing that controls the efficiency and speed of the refinement cycle.
What is vibratory force?
During vibratory bowl processing, the bowl operating channel is converted into a fluidized bed of deburring media. Vibratory media is the tool that is used to either deburr or polish the parts placed into the machine.
The applied force this media can generate on the parts can be partially predicted using Newton's Second Law, F = ma, where the variable m equates to mass.1 In this paper m will be considered to be the weight of the media above the part at mid-channel.
The variable a equates to the acceleration of the mass.1 In other words, an accelerating media mass will apply a greater finishing force to the part surface as compared to a slower moving equivalent weight of media. The formula F = ma will be incorporated into a new formula that will be introduced later in this paper. When measurable process variables are inserted into the new formula a better understanding of efficiency differences between apparently, identically operating vibratory bowls can be calculated.
How is mass m determined?
Mass is the easiest variable to determine and in this paper, it is considered to be the weight, in pounds, of the media column, above the part at mid-channel, as shown in Fig. 1.