by Lushi-Molding  | August 2th. 2019

The Application of 3D printing in plastic molding industry

In recent years 3D printing has become an important part of advanced manufacturing, with positive impact on technology upgrades in various industries. At the same time, with the popularity of 3D printing and the reduction of equipment prices, it is gradual being applicated by more and more families. According to the recently published "Wohlers Report 2018" by the well-known American 3D printing consultancy Wohlers Associates, 3D printing grew by 21% in 2017, with a market value of more than $1.25 billion. It also shows that, by 2020 the value of the 3D printing market will be as high as $21 billion.

3D printing in plastic molding industry

Additive or generative manufacturing, also known as 3D printing or rapid prototyping, has its origins in prototyping or prototyping. In the past, the patterns served as the basis for optimizing the tooling for later injection molding process. In the past, injection molds are usually produced by machining from steel or aluminum and then hardened. This takes a lot of time and cost expensive. Now, through 3D printing the cost can be greatly reduced, and the development phase can be shortened. The possible problems of designing which may occur in the future production process can be precluded and timely improvement, because the later improvements in the late period of the project will cause a great waste of resources.

Using additive manufacturing processes to produce complex geometries such as free-form surfaces, undercuts and cavity injection molds is more easily than before.

Usual 3D printing technologiess

FDM: Fused Deposition Modeling, main materials ABS and PLA The material of FDM process is generally a thermoplastic material such as wax, ABS, PC, nylon, etc., which is fed in the form of a filament. The material is heated and melted in the spray head, which moves along the cross-sectional profile and fill path of the part while extruding the molten material, the material solidifies quickly and bonds to the surrounding material. Each layer is stacked on the upper layer, which play a role in positioning and supporting the current layer.

3D druck for plastic parts

1. SLA: stereolithography. Mein material: photosensitive resin

SLA is the earliest rapid prototyping process. The principle is based on the photopolymerization of liquid photosensitive resin. The liquid material can rapidly undergo photopolymerization under the irradiation of ultraviolet light of a certain wavelength (x=325 nm) and intensity (w=30 mw), the molecular weight sharply increases, and the material changes from a liquid state to a solid state.

2. 3DP: three-dimensional powder bonding. Main materials: ceramic powder, metal powder and plastic powder.

3DP was developed by Emanual Sachs et al. at the Massachusetts Institute of Technology. E.M.Sachs applied for the 3DP (Three-Dimensional Printing) patent in 1989, which is one of the core patents in the field of droplet forming of non-formed materials. The 3DP process is similar to the SLS process and is formed from powder materials such as ceramic powders and metal powders.

3. SLS: Selective laser sintering. main material powder material

SLS also known as selective laser sintering was developed in 1989 by C.R. Dechard of the University of Texas at Austin. SLS is formed using a powdered material. The material powder is spread on the upper surface of the formed part and scraped; the high-strength CO2 laser is used to scan the cross-section of the part on the freshly laid layer; the material powder is sintered together under high-intensity laser irradiation to obtain The section of the part is bonded to the formed part below; when the section is sintered, a new layer of material powder is applied and the lower section is selectively sintered.


What are the common 3D printing materials?

1. Metallic material

The metal material exists in the form of metal powder, metal foil, and wire. Metal materials can be used in industrial grade 3D printers such as selective laser sintering (SLS), direct metal laser sintering (DMLS), and electron beam melting (EMB). By adding the metal into certain engineering plastic materials (such as ABS), it can be made into a wire with certain metal properties suitable for FDM models.

2. Plastics

Plastic materials are widely used by 3D printing. The FDM plastic 3D printer is characterized by high strength, high wear resistance, heat resistance, non-toxicity and no pollution. The more common plastic materials are ABS, PC and PLA.

3. Photosensitive resin

Due to its fast curing speed, the photosensitive resin has excellent surface dryness, and the product has a smooth appearance after molding, and can be transparent to translucent frosted. Due to its good liquid flow and instant photocuring properties, liquid photosensitive resin is the material of choice for 3D printing consumables for high-precision product printing.

4. Ceramic powder

The ceramic powder material is sintered by SLS technology. The glazed ceramic products can be used to hold food. Using ceramics to print personalized cups and then burn them at high temperature after printing.

5. Graphene

Graphene is the new darling of the material industry. It is the world's thinnest and hardest new nanomaterial. Scientists have combined it with 3D printing technology to refill new 3D printed materials. Scientists believe that 3D printed graphene materials are a magical material that will change the world forever.

3D druck materials

The advantages of 3D printing and mold making

Injection mold making is required to produce plastic parts. Then the plastic will be injected into the mold cavity. After a short cooling, the finished plastic part is deformed. This process can be repeated as needed and can efficiently produce hundreds of thousands of plastic parts.

However, the process of manufacturing an injection mold is a time and cost intensive process. To do this, first create a model in the CAD area. The NC program is then created in the CAM department. In production the electrode needs to be machined and then used to etch the mold.

However, if you want to quickly produce the first prototype or small series, the above process take usually too much time. Here, 3D printing has important significance for mold making.

Automation of additive manufacturing

Taking a look into the production of an industrial company, we often find that the manufacturing process from one step to the next is often automated by robots or handling systems. In the current technology additive manufacturing still require a large amount of manual work. Thus, 3D printing represents currently a breakthrough in the traditional manufacturing process.

The automation of plastic injection molding process has not yet been achieved. In the past, additive manufacturing did not focus on automation. Rather, it was about the fast and flexible creation of a prototype. However, as long as 3D printing can produce a large number of products, the subject of automation and process integration will be on the agenda.

3D druck machine
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