The manufacturing industry is one of the sectors that consistently continues to provide the largest national economic growth contribution to reach the target economic growth of 5.3% in 2020. In the 4.0 industry era, the manufacturing industry sector in Indonesia starts to adopt the newest digital technology like artificial intelligence, machine learning, and the internet of things, and additive manufacturing. This research aimed to develop a manufactured product in form of Aluminium cylinder head engine prototype with digital rapid prototyping and Aluminium investment casting. To reach the research goal, the research started from theoretical study and data collection. Next, the cylinder head engine is modelled in CAD (computer-aided design software and printed in 3D printer with polyvinyl butyral and polylactic acid. This 3D printed cylinder head is going to use as moulding pattern. Hereafter, the cylinder head engine is assembled with gating system and coated with a mix of cement plaster, silica sand, and kaolin soil. After the mould is dry, the mould will be burned until the 3D printed pattern is vaporized. The final step is pouring the molten Aluminium at 800°C temperature into the mould. The results showed that the casting process with a cylindrical gating system was perfectly formed, especially for the fins part. However, for the smaller fins, there were still defects in form of lumps. The mix of silica sand, gypsum cement and kaolin soil can create a strong mould. The difference in pattern material does not have a significant effect on the investment casting mould-making process.Keywords: Rapid prototyping, cylinder head engine, investment casting.

Digital prototyping is an innovative design method. With digital product prototyping techniques that are designed with the concept of Generative Design and Topology Optimization, the designer able to visualize and simulate the product start from the design, stress analysis to the product manufacturing process. The aim of this research is to optimization the topology of the product model results of generative design, determine the strength of the model through Stress Analysis used topology optimization 50%, 60%, and 70% of the product model results of generative design and figure the results of the product 3D printing in made prototype models as a result of generative design. This research is conducted in 3 steps, that is the preparation of made models with computing Autodesk Inventor Professional 2020, the analysis with generative design, and the printed with 3D printing. This 3D printed product is made in 2 models. Model 1 with a material reduction of 70% topology optimization was better than 50% or 60% material lighting. Model 2, the maximum of 50% Von Mises Stress reduction is smaller than the 60% and 70% reduction.

This research studies the effect of flow rate on the pouring of molten metal into the mould so that the flow rate into the mould can be controlled. Furthermore, this research studies the effect of mould preheating so that the temperature inside the cavity can be maintained, especially for narrow holes. The process starts with making the engine cylinder head pattern and gating system using a three-dimensional printer with polylactic acid resin. The mould pattern and gating system are combined and coated with a layer of cement plaster, silica sand and kaolin. After the coating is dry, the mould is heated until the mould pattern evaporates and there is no residue. The casting process was carried out at pre-heating moulds of 300 0C and 350 0C and a pouring temperature of 800 0C with pouring speeds of 20, 30, and 40 rpm. The final stage of the research is manufacturing test objects and testing mechanical properties. The results showed that the higher the pouring speed, the less perfect the casting results, especially in the cylinder head fins. The best casting results occurred in the pre-heat condition of the 300 0C mould with a pouring speed of 20 rpm, with a Maximum Tensile Strength of 105 N/mm2, Hardness 53 hardness Brinell test (HBN), Density and Porosity of 2.43 gr/cm3. The material used in this study refers to the reference is A356 Aluminum Alloy.