The Challenge
Validate that 3D printed molds are a viable alternative to machined aluminum or steel molds for prototype and low volume manufacturing runs.
Background
Machined aluminum has become a standard approach for prototype and low volume injection molds. While this saves time and money compared to steel tools, they are still costly and slow to produce. 3D printed tools can combat the price and long lead times, but testing over the past 10 years have shown that printed tools are not robust enough to support low-volume production runs. Tools should be able to reliably produce hundreds of parts to be considered as a viable option for low volume production. Fortify decided to run a life test on a complex design to push the limits in an automated scenario. After 1,000 shots, the test was deemed a success and halted.
THE PROCESS
Utilize Fortify’s DCM Technology to 3D print, a specially designed difficult-to-machine injection mold tool and subject it to high heat and pressures on a press for a minimum of 250 shots. Mold Insert Design Features The 3D Printed tool design included an array of typical and challenging injection molded scenarios:
• Ejector pins to minimize cycle times and process variability
• Shut off feature to showcase part tolerances in an applied setting
• Features as small as 50 micron in height to verify resolution
• Several high aspect ratio rib and pin features with varying draft angles
• Inject polypropylene, a commodity plastic high with a shrink rate
• Complex geometries that would typically require EDM to produce in traditional processing
Mold was cooled for 40 seconds after each shot with an automated compressed air bath. This allowed consistent results for hundreds of shots in a row
The Results
• Auto cycled for two days and one night
• High shrink rate of molded material
• Minimal flash on the tool regardless of shot number
• Overall tool integrity maintained throughout 1,000 shots