A dimensional analysis based model to predict completion of solvent debinding step for Metal Injection Moulded parts

ABSTRACT

The objective of this study is to develop a mathematical model to predict, for instance, the time for complete debinding of a metal injection moulded (MIM) part, the extent of solvent debinding (%) at any point of time and the debinding rate (g/min). To this end, two feedstocks, one containing carbonyl iron powder and the other made from irregular-shaped metallic particles from the shopfloor grinding sludge (both mixed with an organic binder system) were used to make by MIM, parts of nine different geometries. Each geometry has its own modulus. The effects of powder material, solid loading (influencing the binder content) and debinding temperature on the debinding characteristics were studied for the moduli of the nine parts. Parts with smaller moduli (thin parts) were found to debind faster than those with higher moduli. Parts, made of carbonyl iron feedstock (CI90), debind faster than that made of irregular-shaped particulates. A generalised solvent debinding model based on dimensional analysis has been proposed and verified experimentally. The root mean square error was found to be approximately 4% between experimentally determined and predicted debinding characteristics. These predictions are used to effectively design and curtail the solvent debinding cycles in MIM process.

KEYWORDS:

• Solvent debinding
• dimensional analysis
• MIM/PIM
• diffusion

Nomenclature

Acronyms	=	Units
PIM/ MIM	=	Powder/ Metal Injection Moulding
CI90	=	Feedstock having 90 wt. % CI
GSGR75	=	Feedstock having 75 wt. % GSGR
Modulus	=	ratio of volume to surface area
ΔRMS	=	Root mean square errors

Disclosure statement

No potential conflict of interest was reported by the authors.