A FUNDAMENTAL INVESTIGATION OF RECYCLED GLASS AS A MEDIA FOR VIBRATORY MASS FINISHING. Mr. Pitipong Benjarungroj. Supervisor: Dr M Morgan 11 th February 2011. Content. Introduction Aims / Objectives Problem Outline Experimental programme Results. Introduction.
A FUNDAMENTAL INVESTIGATION OF RECYCLED GLASS AS A MEDIA FOR VIBRATORY MASS FINISHING
Supervisor: Dr M Morgan
Centrifugal barrel - Vid
Bowl - Vid
Linear tumbler- Vid
:Flow is amenable to CFD –velocity profiles through 2-D planes
Recycled Glass Media
:-Innovation from Vibraglaz (UK)Ltd.
- materials pre-processing is minimal
- moderate mixing [media possessing varied grain size]
- moderate compaction
- heat treatment
- mould technology (and release agents)
- heating rate, critical temperature (Tmax), duration at Tmax, cooling rate / quenching
Each have a strong effect on media quality
Sample V-Cut media
6 key features that distinguish it from other media:
200x magnification (CAMApp - desktop equipment)
Note Cutting edge density
- Fracture strength
- Cutting edge density (undertaken at intervals tests –test the validity of piranha vs shark analogy)
- Crystallographic structure (influence of grain size on crystal size? Growth?)
- Crystal growth mechanism (temp – time dependency)
Is it like water crystals freezing?
Effect of second or multiple cookings!
HV = F/A;
A = d2/1.854;
Therefore, HV = 1.854F/d2
Where; F =applied load
D = arithmetic mean of the two diagonal d1 and d2
Cannot use stylus methods –stylus wear and lack of information on surface features
The oven used for production of media (-premarket media)
was of a general type used for ceramic components and had
controlled travelling rack (determined cycle time) and
Assessment of this system was undertaken with / without
stacking of moulds.
It was found that media quality varied widely when stacked.
Thermal images where obtained of the production oven and
-wide variation in temperature occurs within
different regions of the oven
Direct View of Laboratory Oven interior
2-D (a) and 3-D (b) Plots of Oven interior
It was established that stacking was problematic and the
company have chosen to design an envelope(conveyor) type oven system to
accommodate single layer moulds.
V-Cut media used in studies
Mass Finisher (vibratory tumbler) used in studies
Region of interest for industry
It can be noticed from the results that the Ra for Aluminium and Brass is higher than
that at which the tests commenced.
This is due in part to the roughing effect of the abrasive and in part to the burnished
condition at which they came to machining (shown later).
Furthermore, most operations with these two materials would primarily be associated
with deburring and/or rounding, not surface roughness.
Polishing would be undertaken with a much less aggressive media.
media 780 is medium grade cutter / polisher
Results are consistent with published data for conventional media
(in-house comparative data being prepared)
Limiting values indicate boundary of performance on particular material
For example: If lower Ra is required with material = aluminium,
then different grade (i.e. polisher) would be needed, though this
would be achieved at the cost of lower material removal rate
media 790 performs more as a polisher than media 780
The abrasive action of the media is evident in the early part of the graph –
i.e. the cutting edges initially dig into and hence roughen the surface
before finishing occurs
This is not so evident with a harder material eg. MS or SS
These laboratory based tests are preparatory tests prior to scheduled
in-situ company (Rolls Royce) confirmation tests
Brass before and after 10 minute of machining
Brass before machining
Brass after machining