Palm Stearin Research Paper

Development of Palm Stearin as Alternative Binder for Metal Injection Molding
11 Amir Arifin , Gunawan
1Department of Mechanical Engineering, Faculty of Engineering, Sriwijaya University, Ogan Ilir 30662 Indonesia [e-mail] Abstract
Palm stearin is one of the fractionation process results from palm oil which palm oil itself is one of the largest several commodities in the world. It has great potentially as an alternative of binder in metal injection molding, moreover, Palm stearin tend to environment friendly because based on organic material so easier to decompose. Palm stearin can be combined with other binder to be a binder system with the function as lubricant and surfactant in a binder system. Experiments showed palm stearin

Comparison 2 type of Binder System: System A; polyethylene, paraffin wax and has palm stearin. System B; Polyethylene, paraffin wax, stearic acid. [27]
In Biomedical material such as 316L stainless steel, Titanium alloy, palm stearin has been used as binder [24, 27-29]. Abdullah et al has reported that palm stearin has successful to use as binder for 316L stainless steel, feedstock 316L stainless steel exhibited homogeneity as shown on the Fig 3. System A and B has consist of Palm Stearin 10vol%, stearic acid 10vol%, respectively. Both of system has similar composition which consists of Polyethylene 35vol%, Paraffin wax 55vol%.
Ibrahim et al, has used binder system with composition binder Polyethylene 40% and Palm Stearin 60% (weight percentage) for mixing with Inconel718 powder for aerospace application. Other researchers also choose 60% Palm Stearin (PS) and 40% of polyethylene (PE) as binder system composition [21, 23, 28] . Palm stearin has shown pseudo plastic flow behavior with shear sensitivity value less than 0.5 which indicating sensitive with shear

Rheological properties of Palm stearin have been performed which showed satisfactory result [20, 24-27, 32]. A result of rheological test is used as indicators for the success of the injection process. rheology result is showed on Fig 6.
Figure 6. Viscosity vs Shear rate of feedstock using palm stearin and polyethylene as binder ooo system at temperature 180 C, 190 C and 200 C[24]
Debinding
Debinding stage is process to remove binder from injected specimen, not a success to remove binder before sintering stage can give defect on the final result, such as, cracking, distortion and contamination[8]. Debinding for removing palm stearin consist of solvent and thermal processes. At solvent process, injected part immersed in fluid to dissolve the palm stearin for subsequent binder burnout. Moreover, residual stress on specimen tend to decrease when lower molecular with viscosity binder are removed [33] .Capillary path and hole are provided by palm stearin after solvent process is used to facilitate higher molecular binder out[20] as shown on Fig 7.
Several researchers using heptanes to dissolves palm stearin from injected part [20, 27].