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E. Balasubramanian et al.
Keywords Direct ink writing · Slurry · Screw extruder · Viscosity · CFD ·
Additive manufacturing
1 Introduction
Direct ink writing is the novel additive manufacturing technique (AM) [1–3] which
is being utilized over a large area of range to fabricate functional parts swiftly.
Compared to other existing AM techniques [4], it does not need any high cost lasers,
support structures, and filaments for extrusion. DIW uses simple screw-type extruder
to extrude high viscosity slurry of the order of more than 50,000 poise [1] which is
very much needed to make components with clay and solid propelleants.
The extrusion technology using screw has become a basic processing technique
to produce various products starting from food processing to rubber and plastics
and nowadays, it is applied to various fields like injection molding, fiber spinning,
compounding, etc. [5]. There are many existing extrusion techniques like piston
extruders, roller-type extruders, screw extruders, plunger extruders, etc. In comparison of plunger extruder, the quality of the ceramic green sample found significantly
better in screw extruder with high surface accuracy and better control of amount of
discharge while changing printing direction [6].
In the production of complex three-dimensional structure, the extrusion technique
plays very important role. The fabrication of complex three-dimensional ceramic
components (up to tens of centimeters) can be done by using freeform extrusionbased additive manufacturing technique known as Ceramic On-Demand Extrusion
(CODE). It provides density near to the theoretical density (>98%). Advantage of
using binder content in small amount is to reduce the post-processing [7]. Also
the Extrusion-On-Demand (EOD), which is termed for precise control on extrusion flow rate, is used in freeform fabrication of high dense complex geometry. The
non-Newtonian behavior of aqueous ceramic pastes make the extrusion more difficult to control and different methods of EOD can be useful [8]. Considering the
green manufacturing approach, manufacturing of ceramic-based components can be
done in eco friendly way by using the aqueous-based extrusion fabrication (ABEF)
method. Water is used as the medium and it is useful for high solid loading ceramic
pastes. The dynamic response of aqueous-based ceramic extrusion process is very
low as compared to incompressible fluid [9].
Recently, utilization of extruders with single screw has progressed significantly.
Single screw extruder with complex screw geometry can be designed and computationally analyzed quickly by applying Hele-Screw approximation of spreading
flow in two dimensions. Solving the Naiver-Stoke equations for the flow starting
from barrel wall provides simulation result in a very short time as compared other
techniques [10]. In case of solid propellant extrusion using single screw, it may be
flammable or explosive. The analysis of rheological state of propellant allow to set
operation parameters to avoid accidents. Increase in rotational speed of the screw
leads to linearly increase in pressure of solid propellant fluid. [11]. Measurement
E. Balasubramanian et al.
Keywords Direct ink writing · Slurry · Screw extruder · Viscosity · CFD ·
Additive manufacturing
1 Introduction
Direct ink writing is the novel additive manufacturing technique (AM) [1–3] which
is being utilized over a large area of range to fabricate functional parts swiftly.
Compared to other existing AM techniques [4], it does not need any high cost lasers,
support structures, and filaments for extrusion. DIW uses simple screw-type extruder
to extrude high viscosity slurry of the order of more than 50,000 poise [1] which is
very much needed to make components with clay and solid propelleants.
The extrusion technology using screw has become a basic processing technique
to produce various products starting from food processing to rubber and plastics
and nowadays, it is applied to various fields like injection molding, fiber spinning,
compounding, etc. [5]. There are many existing extrusion techniques like piston
extruders, roller-type extruders, screw extruders, plunger extruders, etc. In comparison of plunger extruder, the quality of the ceramic green sample found significantly
better in screw extruder with high surface accuracy and better control of amount of
discharge while changing printing direction [6].
In the production of complex three-dimensional structure, the extrusion technique
plays very important role. The fabrication of complex three-dimensional ceramic
components (up to tens of centimeters) can be done by using freeform extrusionbased additive manufacturing technique known as Ceramic On-Demand Extrusion
(CODE). It provides density near to the theoretical density (>98%). Advantage of
using binder content in small amount is to reduce the post-processing [7]. Also
the Extrusion-On-Demand (EOD), which is termed for precise control on extrusion flow rate, is used in freeform fabrication of high dense complex geometry. The
non-Newtonian behavior of aqueous ceramic pastes make the extrusion more difficult to control and different methods of EOD can be useful [8]. Considering the
green manufacturing approach, manufacturing of ceramic-based components can be
done in eco friendly way by using the aqueous-based extrusion fabrication (ABEF)
method. Water is used as the medium and it is useful for high solid loading ceramic
pastes. The dynamic response of aqueous-based ceramic extrusion process is very
low as compared to incompressible fluid [9].
Recently, utilization of extruders with single screw has progressed significantly.
Single screw extruder with complex screw geometry can be designed and computationally analyzed quickly by applying Hele-Screw approximation of spreading
flow in two dimensions. Solving the Naiver-Stoke equations for the flow starting
from barrel wall provides simulation result in a very short time as compared other
techniques [10]. In case of solid propellant extrusion using single screw, it may be
flammable or explosive. The analysis of rheological state of propellant allow to set
operation parameters to avoid accidents. Increase in rotational speed of the screw
leads to linearly increase in pressure of solid propellant fluid. [11]. Measurement