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K. Tesfaye et al.
1 Introduction
Solid propellant is a highly energetic elastomer material composed of different chemicals ingredients like binder, fuel, cross-linking agent, oxidizing agent, curing agent
and stabilizer [1]. The proportion of the chemical ingredients ratio of the propellant composition slurry is reflected in its intended physical and chemical properties.
Furthermore, the burning rate of solid propellants also depends on their shape and
geometry, but traditional production techniques (i.e., casting and extrusion paste
through a die) are not flexible enough to produce complex shapes. On top of that,
the method requires the preparation of mold and mandrel for production of different
shapes, which needs skilled manpower and increases the time and cost of production. In order to manufacture solid propellant with a complex shape with precise
geometry, a new flexible production process, i.e., additive manufacturing (AM) is
required. The additive manufacturing process is able to produce a flexible custom
product with reduced cost and production time [2, 3]. This manufacturing process
produces parts in the layered manufacturing process, wherein the manufacturing
process is controlled from a computer model [4]. Production flexibility and freedom
of AM processes have attracted much attention in various manufacturing sectors,
such as the automotive [5], aeronautics [6], food [7], medical [8], construction [9],
etc.
Nowadays, the adoption of additive manufacturing in the production of solid
propellant paved the way to produce a complex shape with less intervention of
manpower, and researches have been still conducting in this area to further optimize the quality of the product. In the recent past, the production of solid propellant
comes into effect. In 2012 [10], Casting of hybrid rocket fuel grains was fabricated
using additive manufacturing techniques, which was served as mechanical support.
The printing slurry of the additively manufactured grains was prepared by homogeneously mixing Acrylonitrile-butadiene-styrene with paraffin wax. A few years
later [11], a direct slurry extrusion-based additive manufacturing technique called
fused deposition modeling (FDM) was applied to cast fuel grains that could be applicable for hybrid rocket motors and the authors further recommend the technique for
production of composite propellant grain in order to improve the design flexibility.
In 2018 [12], the fabrication attempt of composite propellant grain geometries using
fused deposition modeling (FDM) became successful. The peculiar characteristic of
this manufacturing method was able to customize the part geometry of composite
propellant grains, which is highly improved the burning rates. McClain [13] and his
colleagues developed a new additive manufactured method viz. direct write system,
which has the ability to fabricate low-void propellants with complex geometry.
All the work done so far has focused only on the solid fuel printing process
of the solid propellant and the curing process of the printed parts was done by
placing the final printed part in the furnace just like traditional production techniques.
But these curing techniques take a long time, which increases the speed and cost
of manufacturing. To deal with this problem, the printing and curing process was
synergistically integrated into the presented work. The curing process was applied
K. Tesfaye et al.
1 Introduction
Solid propellant is a highly energetic elastomer material composed of different chemicals ingredients like binder, fuel, cross-linking agent, oxidizing agent, curing agent
and stabilizer [1]. The proportion of the chemical ingredients ratio of the propellant composition slurry is reflected in its intended physical and chemical properties.
Furthermore, the burning rate of solid propellants also depends on their shape and
geometry, but traditional production techniques (i.e., casting and extrusion paste
through a die) are not flexible enough to produce complex shapes. On top of that,
the method requires the preparation of mold and mandrel for production of different
shapes, which needs skilled manpower and increases the time and cost of production. In order to manufacture solid propellant with a complex shape with precise
geometry, a new flexible production process, i.e., additive manufacturing (AM) is
required. The additive manufacturing process is able to produce a flexible custom
product with reduced cost and production time [2, 3]. This manufacturing process
produces parts in the layered manufacturing process, wherein the manufacturing
process is controlled from a computer model [4]. Production flexibility and freedom
of AM processes have attracted much attention in various manufacturing sectors,
such as the automotive [5], aeronautics [6], food [7], medical [8], construction [9],
etc.
Nowadays, the adoption of additive manufacturing in the production of solid
propellant paved the way to produce a complex shape with less intervention of
manpower, and researches have been still conducting in this area to further optimize the quality of the product. In the recent past, the production of solid propellant
comes into effect. In 2012 [10], Casting of hybrid rocket fuel grains was fabricated
using additive manufacturing techniques, which was served as mechanical support.
The printing slurry of the additively manufactured grains was prepared by homogeneously mixing Acrylonitrile-butadiene-styrene with paraffin wax. A few years
later [11], a direct slurry extrusion-based additive manufacturing technique called
fused deposition modeling (FDM) was applied to cast fuel grains that could be applicable for hybrid rocket motors and the authors further recommend the technique for
production of composite propellant grain in order to improve the design flexibility.
In 2018 [12], the fabrication attempt of composite propellant grain geometries using
fused deposition modeling (FDM) became successful. The peculiar characteristic of
this manufacturing method was able to customize the part geometry of composite
propellant grains, which is highly improved the burning rates. McClain [13] and his
colleagues developed a new additive manufactured method viz. direct write system,
which has the ability to fabricate low-void propellants with complex geometry.
All the work done so far has focused only on the solid fuel printing process
of the solid propellant and the curing process of the printed parts was done by
placing the final printed part in the furnace just like traditional production techniques.
But these curing techniques take a long time, which increases the speed and cost
of manufacturing. To deal with this problem, the printing and curing process was
synergistically integrated into the presented work. The curing process was applied