1. Jaikishan Sambharia, Dr. Harlal S. Mali, Jasa Ram
Rheological Investigation and Comparative Study on Synthesized Low Cost Consumables for Abrasive Flow Finishing Processes
Jaikishan Sambharia, Dr. Harlal S. Mali, Jasa Ram
Figure 1. Effect of Abrasive concentration on viscosity of media.
Advance manufacturing and Mechatronics, Mechanical Engineering Department
Malaviya National institute of Technology, Jaipur
ABSTRACT
RESULTS/DISCUSSIONS
ANY OTHER RELEVANT DETAILS
Though presently Abrasive Flow Finishing (AFF) process is mainly used in high end industries e.g. aerospace, automobile, tool & die and prosthetic etc. due to the high cost of the process but if alternative consumables are developed the process has the potential to bring revolution to finishing industry and in turn improving the efficiency of many fuel guzzling / power consuming systems. In this paper, different approaches have been attempted to synthesize an alternative to commercially available media. To ensure the desired properties i.e. visco-elasticity, non-adhesiveness, porosity, permeability, self-lubrication and higher heat transfer coefficient of the synthesized media; different alternative base and plasticizer are used during the synthesization process. Rheological investigation are carried out to observe the effects of media variables on these properties.
Putty+ Gel +Abrasive
Comparative study of alternative media base and additives
Table 1.shows the results and comparison of each alternative media in terms of their desired properties in which higher the numeric value (value from 1-6) represents higher that property in synthesized alternative media.
Property/Composition
Visco
elastic
Non-Adhesiveness
Porosity
Self- lubrication
Ability to remain fluid
Percentage of Abrasive holding capacity
Putty + Gel +Abrasive 3 4
Putty + Grease + Gel + Abrasive
Natural Polymer + Grease + Gel + Clay + Abrasive 2
Putty + Clay + Gel +Abrasive 1
Putty + Clay + Grease + Gel + Abrasive
Putty + Lube Oil + Abrasive
Putty + Lube Oil+ Clay + Abrasive
Putty + Lube Oil + Clay + Gel + Abrasive
Effect of Abrasive concentration on
viscosity of media.
Effect of gel concentration on
viscosity of media
INTRODUCTION/MOTIVATION
Current manufacturing industries, especially, in aviation, automobiles, tools, die and medical implant industries are facing challenges from these advanced emerging materials viz. ceramics, super alloys, composites and nanomaterials that are hard and difficult to finish, demanding high surface quality and accuracy. Low surface quality, finishing of complex and intricate shape workpieces, micro, nano level finish with tight tolerances are the major challenges that leads to development of advance finishing process called Abrasive Flow Finishing (AFF).
AFF process was first patented by the Extrude Hone Corporation in 1970 in which two opposed cylinders extrude a semisolid abrasive media back and forth through passages formed by the workpiece and the tooling. An AFF system consists of three basic elements, that is, machine, tooling, and medium. The machine consists of a hydraulic system and media cylinder that are arranged on a supporting structure. The machine controls the amount of abrasion in the finishing section. Tooling is one of the key components of the AFF system. The main functions of tooling are to direct the flow of the AFF media and specifically control the region of abrasion. Abrasive media is most important element of the process, which is considered a proprietary item of machine manufacturers. Abrasive media is comprised of a base carrier (viscoelastic polymer), rheological additives and abrasive particles. The base carrier is a high-molecular-weight material, with dominant elastic properties and poor viscous properties.
In this paper, on the bases of literature review possible contents of media were identified to synthesize an alternative to commercially available media. Based on comparison of properties of different additives and base, some alternatives media are synthesized. Rheological investigation are carried out for the alternative consumables which are superior in properties to observe the effects of media variables on these properties.
CONCLUSIONS
Effect of shear rate on viscosity
Putty + Grease + Gel +Abrasive
Based on rheological investigation of different alternative consumables following important conclusions have been withdrawn:
1. Based on literature review some AFM media ingredients were identified which have properties like viscoelastic, non-adhesive, good porosity, permeability, self-lubrication property while flowing in complex cavities and higher heat transfer coefficient.
2. After comparison with the properties achieved the best alternative AFM media identified were Putty + gel + abrasive, Putty + grease + gel + abrasive and Natural polymer + grease + gel + bentonite clay + abrasive.
3. Rheological study shows the effect of media variables (abrasive concentration, gel percentage and grease percentage) on viscosity of media by varying temperature and shear rate.
4. When grease is mixed before gel than the synthesized media shows higher viscosity, stiffness and elasticity. When gel is mixed in natural polymer base and abrasives before grease, it become softer and lesser viscous and elastic as compared to media synthesized earlier.
5. Results shows that viscosity increases with increased in abrasive concentration in media when gel concentration (20%) is kept constant. Also viscosity decreases with increased in percentage of gel in media when abrasive concentration (35%) is kept constant.
6. Rheological studies shows decrease in viscosity of media with increased in shear rate. This shows the shear thinning behavior of non-Newtonian types of fluid.
7. From rheological study, results shows that media viscosity decreases with decrease in concentration of Grease (Gr) and increase concentration of gel (G).
Effect of Abrasive concentration on viscosity
of media at 10, 15% Gel concentration
Effect of abrasive concentration on viscosity
of media at 5, 10% Grease concentration.
MATERIALS/METHODOLOGY
Based on literature review some AFM media ingredients were identified which have properties like viscoelastic, non-adhesive, good porosity, permeability, self-lubrication property while flowing in complex cavities and higher heat transfer coefficient. Based on literature some media base are silicon rubber (a-silicon, p-silicon), ester based polymer, commercial putty (silly putty); abrasives (Silicon carbide, aluminum oxide, cubic boron nitrides abrasives, diamond) and additives i.e. clay (bentonite, salacious earth powder), silicon oil, lube oil, crude oil, varnish oil.
Different samples were synthesized by mixing variants of base and additives to get alternative AFM media which have greater permeability to absorb more quantity of abrasive and capability to hold the abrasives with higher bonding strength.
During synthesization of alternative AFM media, abrasive mesh size of 320 is used and for gel preparation 2% by weight powder is used to make solution of gel. The rheological experiment were conducted on atmospheric condition (at 25 °C). The rheological experiment were carried out on Anton Paar make Rotational Rheometer with temperature range (-20 °C to 180 °C) and shear rate range (0.01 to 4000 sec.-1). During rheological experiment, shear rate was in range of sec-1.
After synthesization, rheological study were carried out to study the effect of media variables (abrasive concentration, gel percentage and grease percentage) on viscosity of media by varying temperature and shear rate.
REFERENCES
Effect of shear rate on
viscosity of media.
Effect of temperature (25-95°C) on viscosity for two
alternative media (putty + gel and putty + grease + gel).
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T.R.Loveless et al., "A study of the effects of abrasive flow finishing on various machined surfaces," J.Mat. Processing Tech, 1994; vol. 47, pp
J. Sambharia et al., "Characterization and Performance Evaluation of Developed Alternative Polymer Abrasive Gels for Abrasive Flow Finishing Process," Int. J. of Precision Tech., ; no. In Press.
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H. S. Mali et al., "DEVELOPING ALTERNATIVE POLYMER ABRASIVE GELS FOR ABRASIVE FLOW FINISHING PROCESS," in AIMTDR2014, IIT Guwahati, 2014.
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L. J. Rhoades, "Process and apparatus of abrading by extrusion"., 1990; USA Patent 4,996,796.
Natural polymer + Grease+ Gel + Clay + Abrasive
Effect of gel and grease concentration on viscosity for
different abrasive concentration alternative media
Effect of gel and grease concentration
on viscosity of alternative media.
ACKNOWLEDGEMENT
We acknowledge Department of Science and Technology (DST), New Delhi, India, for their financial support for project no.SR/FTP/ETA-0078/2011 Dated 17/09/2012.
Effect of shear rate (1-100 sec-1) on viscosity of alternative media.