Some observers in the plastic manufacturing industry, e […]
Some observers in the plastic manufacturing industry, especially those with vested interests, hope to convince you that 3D printing will become the end of Plastic Pail Mould. Although 3D printing makes sense in some cases, reports of the death of injection molding have been greatly exaggerated.
Plastic injection molding is a real production method that has been tested in practice and will not disappear soon. This is a basic and reliable method of producing high-quality plastic parts. Despite recent improvements in 3D printing technology, and these improvements may appear in the future, the fact is that more than 80% of the plastic parts used in today's products must be injection molded.
The answer to the question is: "Which manufacturing method is best for me?" Yes, "It depends." It depends on variables such as quantity, quality, and cost.
Quantity
David Kazmer, a professor of plastics engineering at the University of Massachusetts Lowell, said in a published paper that for 3D printing with a small number or less than 50 units, it currently makes sense for the fastest "procurement to mass production time". .
Therefore, for production, injection molding is still the best manufacturing method, especially considering that 3D printing requires a longer production time than injection molding.
There is an emerging "hybrid" approach, that is, only 3D printing mold inserts, and then injection molding to produce parts. For some limited applications, 3D printing plug-ins can be used as product development and a very limited number of test molds. 3D printing molds usually only use 60 to 180 parts.
Kazmer's research looked at situations where 3D printed tooling blades might be suitable, and concluded that metal blades (surface finish and machine cost) and polymer blades (surface finish and poor strength and heat transfer) still exist Major issues. .
quality
One of the main limitations of 3D printing is the inability to manufacture parts with the same physical properties as conventional injection molded parts. Although the number of various materials that can be used for 3D printing seems to have been increasing, it is still limited compared to all the various plastic materials that can be injection molded. Although a 3D printed prototype can be used to evaluate its shape, if the material used for the prototype is different from the production part, the characteristics of the material cannot be tested.
Another issue mentioned in Kazmer's research is surface finish. Although the surface finish of the part may vary depending on the quality (expensive) of the 3D printer, it still does not match the smooth surface that a polished steel injection mold can achieve.
Last but not least, tolerance is an issue in the list of quality differences. Although advanced process design (such as parallel printing) and optimization are expected to improve the ability of 3D printing to maintain tighter part tolerances, the quality of parts achieved by 3D printing today is worse than injection molding.
cost
Assuming that the aforementioned quality issues do not rule out the possibility of 3D printing as an out-of-door option, the total cost of 3D printed parts depends on the quantity produced, compared with injection molded parts. In Lowell's research, the cost of 3D printing 300 of a certain size part is $20 per piece. The unit price for injection molding a million of these units with a steel mold is only $1.13.
Another cost factor to consider is the cost factor associated with design changes in the prototype stage. In 3D printing, there is no need to iteratively modify the mold for the prototype. Just make design changes to the CAD model.
In injection molding, design changes to steel molds are usually easy to manufacture and relatively cheap, but for aluminum molding tools, design changes may cost all new molds.
In addition, new simulation software can now be used to help solve injection molding challenges in the software-rather than through expensive, time-consuming prototype iterations. Testing molds in a virtual simulation environment overcomes communication barriers, allowing designers, mold makers, and manufacturing professionals to collaborate more effectively, while eliminating the need for expensive prototypes and mold cycles.
For 3D printing and injection molding, when you can answer these questions about the required quantity, quality and cost, you will provide the best production method for your parts.