When it comes to the fast and high-quality production of plastic components, the two processes 3D printing and injection molding are considered the most economical. While the injection molding process is a tried and tested manufacturing method in the area of series production, even of large quantities, manufacturers are still skeptical about 3D printing. Additive manufacturing is ideally suited for prototypes - but for the production of large batches?
With this article, we would like to provide you with a decision-making aid and answer the question of when which production method is suitable for your components.
Injection m olding is used in the production of identical plastic parts in large or very large batches. In the injection molding process, a negative mold of the part to be produced is first designed and then milled from solid material - usually aluminum or steel. This mold is then installed on the injection molding machine. The liquefied, heated material is then injected into the mold, cools there and can then be removed from the mold as a finished component.
3D printing, on the other hand, does not require the prior production of a mold. In the additive manufacturing process, the respective component is created layer by layer in the build space of the 3D printer. Once printing is complete, the component can simply be removed from the printer. Depending on the technology, support structures may have to be removed afterwards.
The mold required for the production of injection-molded components is complex to manufacture and thus involves high initial costs. Changes to the geometry of the components always entail an adjustment of the mold - which takes time and thus produces further costs. The advantages of the injection molding process lie in its high precision and speed. When very high volumes with tight tolerances or the highest surface qualities are required, injection molding has an advantage.
3D printing completely eliminates the initial cost of manufacturing molds. The components can be manufactured directly from the design file (CAD) without any detours. Any changes to the geometry of the components can also be implemented during ongoing production without any great loss of time. Some geometries can even only be produced using 3D printing processes! 3D printing processes always have an advantage when it comes to series production that is as flexible as possible with the option of quick changes even during ongoing production.
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For a decision for or against a process in the field of series production of plastic components, several parameters must be considered and compared. The most important decision criteria include:
3D printing processes, on the other hand, offer the possibility of adapting or modifying components at any time. By digitally intervening in the existing design data, optimizations to the component can be realized in a very short time and implemented immediately with the next batch of parts to be printed.
Modern 3D printing processes such as Digital Light Processing (DLP), Selective Absorption Fusion (SAF) or Multi Jet Fusion (MJF) now enable the economical production of plastic components in large series of up to 10,000 units. Particularly when several components can be printed together in a single production step, additive manufacturing offers an immense time advantage, even for larger series.
Injection molding is the more advantageous process for high batch sizes above 10,000 pieces if no changes to the geometry are to be expected. Due to the high initial costs for the injection molding tool, the quantities are limited downwards - below 1000-10,000 pieces, the production of a tool is usually not worthwhile.
Even though modern 3D printers can superimpose the thinnest layers, the individual layer details of a component are always visible and noticeable. This makes post-processing necessary if the components must have particularly smooth surfaces (for example, bearing elements in mechanical engineering). However, depending on the geometry of the components, the technologies DLP (Digital Light Processing) and SLA (Stereolithography) also enablesurfaces similar to injection molding.
In injection molding, the material is poured into the mold in a single process, so that no layers are visible or burrs are noticeable. The surface quality here is always identical throughout series production, and reworking is either not necessary at all or can be done cost-effectively using automated finishing processes.
Before injection molded parts can be produced, the mold for the parts must first be made. Then the injection molding machine must be set up and adapted for series production. The individual work steps significantly increase throughput times. A further loss of time occurs if changes to the component become necessary during production. Here, the existing mold then either has to be reworked or even made from scratch.
With the 3D printing process, no time-consuming preparatory work or setup times need to be included in the calculation. Once the design data has been created, production can begin immediately. Changes to the part geometry can be implemented immediately in the design files and incorporated in the next print batch. This makes the 3D printing process particularly interesting for time-critical jobs.
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Injection molded components are limited in terms of possible geometries - because only those contours are possible that can be represented in the negative mold using machining processes. Complex geometries can be realized with slides or special tools, but are then also on a different level in terms of cost.
With 3D printing processes, on the other hand, there is maximum freedom of design. Virtually all geometries, as well as moving parts or entire assemblies, can be produced with a 3D printer. The more complex the design of a component, the greater the advantages offered by modern 3D printing processes.
The following applies to injection molded parts: The first part of a series is the same as the last part. Changes in ongoing production, for example adapted contours or optimized geometries, are always only possible by adapting the mold used. This tool must be reworked on a milling machine or completely newly manufactured. During this period, the actual series production of the plastic components is at a standstill.
3D printing processes , on the other hand, offer the possibility of adapting or modifying components at any time. By digitally intervening in the existing design data, optimizations to the component can be realized in a very short time and immediately implemented with the next batch of parts to be printed.
During the production of parts by injection molding, virtually no waste is produced, because exactly as much material is always put into the mold as is required for the individual component. However, injection molding is a very energy-intensive process, and that in two respects. This is because both the production of the mold and the manufacture of the components require the operation of machines that in some cases use electric motors with drive powers of several kilowatts. Added to this is the use of environmentally harmful auxiliary and operating materials, such as oils or cooling lubricants. Last but not least, the production of molds generates waste in the form of chips, which must be disposed of at high cost and fed into the recycling loop.
In the case of 3D-printed parts, minimal waste is generated when support structures have to be removed or edges smoothed. However, that's about it - because no operating or auxiliary materials or large electric motors are needed for manufacturing. Accordingly, 3D printing has a clear advantage in sustainable manufacturing with the least possible use of resources.
Both the 3D printing process and the injection molding process offer their very own advantages and disadvantages. The big benefit is to use both economically.
You should use the injection molding process to produce your components if:
The 3D printing process, on the other hand, is to be preferred when:
Do you still have questions about the optimal production method for your component or would you like to discuss a specific project with us? Then give us a call or write to usright away! Our experts are available for you at any time and look forward to hearing from you!
Requirements for highest surface quality, geometries from 3D printing? How about investment casting technology? The hybrid process combines the advantages.
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