Sacrificial additively manufactured molds for use in injection molding processes
Sacrificial additively manufactured molds having a dissolvable material for use in thermoplastic injection molding processes at plastic melt temperatures in the range of 70-450 degrees C. and injection pressure in the range of 0.2-400 MPa. A method of producing a molded article using said sacrificial additively manufactured molds is also disclosed.
1. A method for producing a molded article comprising the steps of:
a. printing a sacrificial additively manufactured mold in an additive manufacturing apparatus, said mold having a cavity enclosed by an outer shell comprising a dissolvable radiation-cured material which material (i) in its uncured form is a selectively-curable resin or mixture of selectively-curable resins, and (ii) when cured can withstand plastic melt temperatures in the range of 70-450 degrees C. and injection pressures in the range of 0.2-400 MPa when formed as said outer shell,
b. post-processing the additively manufactured mold obtained in step a,
c. filling the additively manufactured mold obtained in step b with thermoplastic building material using an injection molding process, wherein during said filling, a mold tool configured to receive and hold a build plate of the additive manufacturing apparatus with the sacrificial additively manufactured mold attached thereto is used,
d. processing the building material of step c in order to produce a molded article inside the additively manufactured mold,
e. dissolving the additively manufactured mold in order to release the molded article obtained in step d, and
f. rinsing the molded article,
wherein the sacrificial additively manufactured mold is printed by a method involving photopolymerization.
2. The method according to claim 1 , wherein the sacrificial additively manufactured mold is printed by means of UV-Digital Light Processing (DLP); UV, laser, LCD or stencil Stereolithography (SL), continuous liquid interface production (CLIP); Material jetting or Binder jetting; optical fabrication; photo-solidification; solid free-form fabrication; solid imaging; or a droplet/“ink” jet-based system.
3. The method according to claim 1 , wherein the sacrificial additively manufactured mold is cured by subjecting the dissolvable radiation-cured material to UV radiation.
4. The method according to claim 1 , wherein the post-processing of step b comprises at least one of the following steps: cleaning the mold, drying the mold, surface-treating the mold and post-curing the mold.
5. The method according to claim 4 , wherein the sacrificial additively manufactured mold is post-cured by subjecting the mold to UV post-curing or thermal post-curing or a combination of UV post-curing and thermal post-curing.
6. The method according to claim 1 , wherein the mold is filled with building material selected from the group consisting of: a thermoplastic polymer, a thermoplastic elastomer, a thermoplastic composite, thermoplastic rubber, a thermoplastic feedstock comprising metal powders, and a thermoplastic feedstock comprising ceramic powders.
7. The method according to claim 1 , wherein the mold is filled in step c using one of: thermoplastic injection molding, thermoplastic rubber injection molding, thermoplastic micro injection molding, thermoplastic powder injection molding, thermoplastic metal injection molding, thermoplastic ceramic injection molding, thermoplastic blow molding, thermoplastic over molding, thermoplastic compression molding, thermoplastic insert molding, or thermoplastic multi-shot molding.
8. The method according to claim 1 , wherein mold tool has a cavity with dimensions that conform to outer dimensions of the outer shell of the sacrificial additively manufactured mold.
9. The method according to claim 1 , wherein the mold tool has dimensions that conform to outer dimensions of the outer shell of the sacrificial mold.
10. The method according to claim 8 , wherein the mold tool has a vacuum channel in fluid communication with the mold cavity whereby filling is assisted by drawing a vacuum into said cavity prior to or during filling of the mold in step c.
11. The method according to claim 1 , wherein the mold is dissolved in step e by immersing the mold with the molded article in a solvent or a combination of solvents selected from the group consisting of: water, sodium hydroxide, limonene, acetone and ethanol.
12. The method according to claim 1 , wherein at least two of the process steps a, b, c, d, e, and f are performed independently of each other in different apparatuses.
13. The method according to claim 12 , wherein transfer of the sacrificial additively manufactured mold between the different apparatuses is performed either manually or automatically or the transfer is performed by a combination of manual and automatic transfers.