December 2018

Plastics Plus Technology Inc, has worked closely with one of our partners to develop 3d printed mold cavities for evaluating new injection molded part designs. With the help of our tool room PPT was able to configure a retired mud mold to accept 3d printed cores and cavities for use in prototype development.

The 3d printed cavities have been very helpful in market testing and bringing products to market quickly without the expense of a full blown injection mold tool. Currently we are producing small prototype parts from TPE materials but there is potential to create parts from ABS or other materials in future products. There are limitations on what types of materials we can ruwith the 3d printed cavities. For instance, high temperature engineering grade materials are not good candidates for cavities produced from this particular material. Generally materials with lower melt temps work best for use in 3d printed molds utilizing this technology. The cavities have poor cooling characteristics and the cycle times can be very long.

The 3D printed cores and cavities were produced with Vero white material on a Stratasys Polyjet 3D printer. This printer uses a process called photopolymerization to print objects. The photosensitive Verowhite resin material is applied layer by layer and cured with a UV light to create a very detailed and high resolution object. Parts and cavities produced with this kind of technology can have very good surface finish when compared to other 3d printed technology.

There are some design considerations to consider when developing parts that will use 3d printed mold cavities:

The cycle time is very long. 3d printed cavities do not have the same cooling characteristics as typical mold tooling.
Not all materials are good candidates for 3d printed cavities. High temperature materials do not work well
Make sure the parts have adequate draft, at least 5 degrees draft is recommended
Make sure any engraving or embossing is large enough to fill properly
Cavities may require polish to eliminate layer lines
Mold release may be required to prevent sticking of parts
Ejection should be thought of in advance, how do you plan on removing the part. TPEs can be pulled from cavity easily while ABS or rigid materials may require pin ejection

Tariffs have increased the cost of buying products from China. Components commonly used in injection molded products have been affected as well. These components include terminals that are used in electrical components, various inserts and other materials produced in China. At this time the tariff adds approximately 10% to the cost of the good sold but this could increase to 25% after 2019. Raw materials such as steel have higher tariffs.

A tariff of 25% on Imported Chinese steel has also been put into place. This added cost is cause for concern to molders who use imported Chinese steel to build their tooling. Naturally the injection mold industry is heavily dependent on steel for the production of their tools, for small precision close tolerance molds the raw material cost is only 10% of the total mold costs. Steel cost is a larger percentage of the cost for Large molds and molds that have less stringent quality requirements. For those molders who import finished mold tooling, the cost could be much higher, adding upwards of $10,000 to the mold cost. The good news is that the tariffs on steel produced elsewhere have been lifted. Steels produced in Mexico, Canada and Europe are not affected by these tariffs.

PPT works with local sources for tooling and materials so thus far we have not seen a big impact on tooling costs. Inserts however are another story, early in 2018 we immediately began to see tariff costs passed down from suppliers. Where possible, we searched for alternative sources for inserts and terminals that could be produced in the USA or Mexico.

While it appears that both China and the USA will eventually agree on a new trade deal, nobody can predict when. Until then, there will be pressure to use alternative sources produced anywhere but China.

3D Printed Cavities to Produce Prototype Samples

Tariffs on Chinese Producers

Latest Post

Measuring Surface Finish on a Plastic Part using GD&T Principles and Profilometers