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Arad Group

PolyJet Technology Propels
High-Requirement Prototyping

“3D printing injection molds enabled us to quickly
produce functional prototypes that we could test in
the field, dramatically reducing our time to market.”
– Avi Zelig, Arad Group

3D Printed Injection Molds

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Injected parts from 3D printed molds

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Injection molded part being ejected from 3D printed mold

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Welding process for injected parts

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Microscopic image of the welding area

Demanding requirements govern the design, testing and production of the watertight components that protect electronics. The ultrasonic welding required to seal the parts together can only be tested on real components in the final material, typically produced using an aluminum test mold or even the final steel mold. These metal molds cost $5,000-$20,000 and take four weeks to three months to produce. If the welding trial reveals needed design improvements, the mold-making process starts again and the cost multiplies.

Instead, Arad now creates injection molds using its PolyJet 3D Printer. The design includes a step joint for the welding process, which provides high strength and good aesthetics since the welding melt partially encapsulates the joint. The molds are 3D printed using Digital ABS™ material in four parts:
the core, cavity and two inserts to create the negative draft. The total printing time is just 10 hours.

Ready for Welding

After the injection molds are printed, the male and female parts are mounted on an injection molding machine and injected using two different materials for testing: Grilamid TR90 (amorphous nylon) and
ABS 757. Once the parts are injected, they are welded together for a watertight fit with the electronic components inside.

“3D printing injection molds enabled us to quickly produce functional prototypes that we could test in
the field, dramatically reducing our time to market, which is absolutely vital in this competitive industry,” Avi Zelig, Arad Group mechanical engineer, said.

By using 3D printed injection molds to produce functional prototypes, Arad has reduced its time to market by five weeks, and its prototype production costs by 80 percent.

Method

Cost

Time

3D Printed Mold $2,000 10 hours
Metal Mold for Prototype Testing $5,000 4 weeks
Metal Mold for Final Production $20,000 2 months

Injection Molding Parameters

Material

Grilamid TR90
(amorphous nylon)

ABS 757

Temp Profile e 250-255-260-265-260 190-220-220-230-240
Injection Pressure 880 bar 640 bar
Shot Size 38 cm3 38 cm3
Switchover Point 8.5 cm3 26.5 cm3
Packing Pressure 200 bar 200 bar
Cooling Time 140 seconds 60 seconds

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