Design and manufacture of polylacticacid (PLA) filament storage for 3-dimensional printing with composite material.

3-dimensional printing is an additive manufacturing (AM) method using polylacticacid (PLA) filaments. However, PLA filaments still have limitations such as the hygroscopic properties of the material. This type of filament easily absorbs air from air humidity, so it will have an impact on the chemical damage of PLA. In this research, a composite file storage area will be designed. The method of making this file storage area will use a composite material Medium Density Board (MDF) with a simple manufacturing method. The filament storage area is expected to prevent and reduce air absorption and the lifespan of filaments in PLA filaments, thus helping users of 3-dimensional printing produce better results.


Introduction
Additive Manufacturing (AM) technology is an manufacturing activity that build 3D components using materials in the form of polymers, concrete, metal or composite materials [1]. Based on research conducted by Herianto, in his journal entitled "The framework predicts the use of 3D printing in Indonesia in 2030", 53% of additive manufacturing methods are predicted to be used in industrial processes [2]. This shows that technology Additive manufacturing is one of the options in product manufacturing. The most common problem in using 3D printing is wet filaments. One of the effects of absorbing water into the 3D printing filament is to make components brittle, produce porosity, and affect the flow characteristics and macrostructures produced from FDM parts [3].

Additive Manufacturing
Additive Manufacturing (AM) is a manufacturing activity that build 3D components with materials in the form of polymers, concrete, metal or composite materials [1]. Additive manufacturing involves 3 important aspects, namely making designs with a computer or Computer Aided Design (CAD), cutting and manufacturing 3D lines with slicing software and printing using 3D printing methods [1].  [2]. However, according to global technology & telecommunications research expert Thomas Alsop, the FDM method is the most used method since 2020 as a 3D printing method.

PLA Material Characteristic
Polylactic acid (PLA) is a bioplastic material made from organic materials such as corn, sugar cane and wheat [1]. Based on the nature of the material, PLA is a hygroscopic material, which means that it can absorb water contained in air humidity, thereby reducing the quality of the filament [4]. PLA has hydrolytic properties which are material properties which can be degraded by water [5]. According to Victor Ugaz, a teaching lecturer in chemical engineering from A&M university as stated on the youtube channel "Victor Ugaz", the hydrolytic degradation process of PLA as illustrated in figure  1 above begins with the input of water chemical groups (H2O) into the PLA chemical groups ( C3H4O2). The H20 group then breaks the bonds of the C3H4O2 group into C3H5O2 bonds, resulting in the degradation of the PLA material [6].

MDF material
To keep the temperature in the filament storage from getting too hot, the material used is engineered wood material such Medium Density Fiberboard (MDF). MDF is an engineered wood product made by breaking hardwood or softwood into wood fibers, and combined with a resin binder to form wood panels [7]. Based on MDF standardization data (SNI -01-4449-2006), the suitable MDF material to be used is MDF type 30 material which has a fracture modulus (MOR) of 30 Kgf/cm 2 and a modulus of elasticity (MOE) of 2500 Kgf/cm 2 .

Aesthethic Quality Index
One of the problems that occur in 3-dimensional printing is the problem of aesthetic quality.  According to the research conducted by Galati Manuela in a journal entitled "A methodology for evaluating the aesthetic quality of 3D printed parts", common problems that often arise in FDM printing as shown in Figure 2 are as follows [8]: • Overheating, (Figure 2-a) is a condition that occurs when the next layer is deposited while the polymer material in the previous layer has not cooled. Based on an experiment conducted by Stevan on his YouTube channel "CNC Kitchen", one of the phenomena that occurs in wet PLA filaments is foaming and hydrolysis [8]. Foaming is a condition where water evaporates inside the filament when the filament is heated through the hot end and produces holes and results inconsistent extrusion. Hydrolysis occurs when the polymer chain contained in the filament PLA becomes damaged by water and causes the filament to become brittle. One of the signs that can be seen in wet filament printing results is that there is stringing in the printing results even though the machine is properly calibrated.. To evaluate the aesthetic quality in 3-dimensional printing, the Aesthetic Quality Index (AQI) calculation method is used where this calculation method can be determined by the following equation as shown on figure 3 [9].    Design process for design and manufacturing of PLA storage begin with collecting voice of customer via survey on 3d printing community in Indonesia. The data gathered from survey will consist of which brand of PLA are used often, which problem that frequently occurs in the community and which function they want the most in PLA filament storage. The data collection then continued with gathering measurement data of operator hand and dimension of filament spool that are available on the market. The data then analyzed using kano model and Pugh matrix method to determine which function should be prioritized before making 3D model and mechanical drawing of the product.

Data collection diagram of 3dimensional printing
The procedure for data collection of 3D printing results is as shown on figure 5 below: Normal room temperature and humidity data collection is done to get the average normal room temperature and humidity within 1 hour 40 minutes. This data will then become a constant variable which will be compared with the humidity conditions in the filament storage on the market and with the proposed product. The printing will use a "benchy" 3D dimensional design. 3D benchy is used because it has geometric features that are challenging to print, such as curved surfaces (hulls), small surface details (writing on the stern of ships), cylindrical shapes (chimneys), flat overhangs (rectangular roofs and window tops), sloping surfaces low, and circular horizontal holes (windows) [10].

Analysis Moisture Effect on PLA Filament Storage
Based on research procedure above, the analysis of moisture effect on PLA Filament aesthetic quality are as following.  Figure 6. Effect of AQI Value of storage condition Open space refers to the filament that stored in open space area and exposed to humidty in open air. Market product 1 refers to drybox and market product 2 refers to vacuum bag used in this research. Suggested product refers to the filament storage box which is made using MDF material and Egg incubator heater. The filament brand used in this research are CCTREE, ESUN and Creality. The moisture level during this research range from 60-70%. In CCTREE filament, the AQI value will be constant at 16 if stored in Fillabox and drybox products rather than open space. This shows that the Suggested product is equal to market product 1 in terms of value aesthetic quality index (AQI) and is able to improve quality printing. When compared to storage in market product 2, the suggested product is superior because it can produce quality values good aesthetics and stable. In addition to the creality filament, the AQI value will be constant at 16 if stored in the suggested product. When compared to the increase scores from 14 to 15 on market product 1, the suggested product is superior. This indicates that for the creality filament, storage at suggested products increase AQI scores more effectively than with storage in market product 1. In addition, the AQI value of the suggested product is at a stable value and close to market product 2. This shows that the filament that has produced bad printing quality can produce good quality if using the suggested product.
For esun filament, the AQI value will be constant at 16 before dropping to a value of 15. When compared to the market product 2 or 1 which there is a decrease in value from 16 to 15 Suggested products are superior in increasing the AQI value. This shows that for esun filament, storage on the proposed product will increase the value AQI more effectively.

Analysis of MDF material of suggested product
In determining a good MDF material for filament storage, the material specifications are focused on the modulus of fracture (MOR) and modulus of elasticity (MOE) which have specifications that match or are close to the specifications of Type 30 MDF. MDF materials are divided into several variations based on the constituent materials. including the following [7]. Based on the results of the material specifications in table 2 above, the type of MDF used will be based on material from bagasse. MDF board made of bagasse has a relatively high fracture modulus of 13.9 -27.8 MPA and a relatively low modulus of elasticity of 1481-2635 MPA. In addition, MDF made from bagasse material has a low thickness addition of 21-23.5%. This is also in accordance with the SNI specification standard for MDF material (MDF) Type 30 where type 30 MDF material has a fracture modulus for dry MDF of 30.0 Kg/cm 2 , 306.0 Kg/cm 2 and wet of 15.0 Kg/cm 2 , ≥ 153.0 Kg /cm 2 . while the modulus of elasticity is 2500 Kg/cm 2 .