WHITE PAPER
Low-Volume Rapid Injection
Molding With 3D Printed Molds
This white paper provides methods and guidelines for using stereolithography (SLA) 3D printed
molds in the injection molding process to lower costs and lead time. Through the real-life
case studies with Braskem, Holimaker, and Novus Applications, you’ll learn how this hybrid
manufacturing process enables on-demand mold fabrication to quickly produce small batches of
thermoplastic parts.
December 2020 | formlabs.com
,Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Process Workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Other Best Practices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Braskem Fabricated 3000 Mask Straps in a
Week With a High Temp Resin Mold Insert. . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Holimaker Produces 100s of Technical Parts With Grey Pro Molds . . . . . . . . 12
Novus Applications Inject Molded Hundreds of
Threaded Caps With a Rigid 10K Three-Parts Mold . . . . . . . . . . . . . . . . . . . . 16
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
FORMLABS: Low-Volume Rapid Injection Molding With 3D Printed Molds 2
, Introduction
INJECTION MOLDING
Injection molding is one of the leading processes for manufacturing plastics. It is widely used
for mass-producing identical parts with tight tolerances. It is a cost-effective and extremely
repeatable technology that yields high-quality parts for large series. It can produce volumes from
1,000 to 100,000+ of parts at very low unit costs. Injection molding has a short cycle time, with
each machine capable of building new parts every 15 to 60 seconds. It is a fast, intensive process
where high heat and pressure are involved to melt thermoplastic and force it inside a mold.
Because of these extreme molding conditions, the tools are traditionally made out of metal by
CNC machining or electric discharge machining (EDM). These are expensive industrial methods
that require specialized equipment, high-end software, and skilled labor. As a result, the
production of a metal mold typically takes four to eight weeks, and costs anywhere from $2,000
to $100,000+ depending on the shape and the complexity of the part. Due to these high costs,
manufacturers are looking at ways to minimize the cost of custom tool production and reduce
lead times to bring products to the market faster.
Desktop 3D printing is a powerful solution to fabricate injection molds rapidly and at low cost. It
requires very limited equipment, saving CNC time and skilled operators for other high-value tasks
in the meantime. Manufacturers can benefit from the speed and flexibility of in-house 3D printing
to create the mold and couple it with the production force of injection molding to deliver a series
of units from common thermoplastics in a matter of days. They can even achieve complicated
mold shapes that would be difficult to manufacture traditionally, enabling development teams to
be more innovative. Furthemore, product development benefits from the ability to iterate on the
design before investing in hard tooling.
Even though 3D printing molds can offer these advantages when used appropriately, there are
still some limitations. We should not expect the same performance from a 3D printing polymer
mold as from a machined metallic one. Critical dimensions are harder to meet, cooling time is
longer because the thermal transfer occurs slower in plastic, and printed molds can easily break
under heat and pressure. However, some companies managed to produce series of hundreds of
parts with printed molds and even thousands of shots for very simple designs. Low-run injection
molds are great assets for engineers to deliver limited batches of end-use parts or prototypes in
the final plastic, for pre-production tests.
FAST FABRICATION OF SHORT-RUN INJECTION MOLDS
Stereolithography (SLA) printing technology is a great choice for molding. It is characterized by a
smooth surface finish and high precision that the mold will transfer to the final part and that also
facilitates demolding. 3D prints produced by SLA are chemically bonded such that they are fully
dense and isotropic, producing functional molds at a quality not possible with fused deposition
modeling (FDM). Desktop SLA printers, like those offered by Formlabs, simplify workflow as they
are easy to implement, operate, and maintain.
FORMLABS: Low-Volume Rapid Injection Molding With 3D Printed Molds 3
Low-Volume Rapid Injection
Molding With 3D Printed Molds
This white paper provides methods and guidelines for using stereolithography (SLA) 3D printed
molds in the injection molding process to lower costs and lead time. Through the real-life
case studies with Braskem, Holimaker, and Novus Applications, you’ll learn how this hybrid
manufacturing process enables on-demand mold fabrication to quickly produce small batches of
thermoplastic parts.
December 2020 | formlabs.com
,Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Process Workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Other Best Practices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Braskem Fabricated 3000 Mask Straps in a
Week With a High Temp Resin Mold Insert. . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Holimaker Produces 100s of Technical Parts With Grey Pro Molds . . . . . . . . 12
Novus Applications Inject Molded Hundreds of
Threaded Caps With a Rigid 10K Three-Parts Mold . . . . . . . . . . . . . . . . . . . . 16
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
FORMLABS: Low-Volume Rapid Injection Molding With 3D Printed Molds 2
, Introduction
INJECTION MOLDING
Injection molding is one of the leading processes for manufacturing plastics. It is widely used
for mass-producing identical parts with tight tolerances. It is a cost-effective and extremely
repeatable technology that yields high-quality parts for large series. It can produce volumes from
1,000 to 100,000+ of parts at very low unit costs. Injection molding has a short cycle time, with
each machine capable of building new parts every 15 to 60 seconds. It is a fast, intensive process
where high heat and pressure are involved to melt thermoplastic and force it inside a mold.
Because of these extreme molding conditions, the tools are traditionally made out of metal by
CNC machining or electric discharge machining (EDM). These are expensive industrial methods
that require specialized equipment, high-end software, and skilled labor. As a result, the
production of a metal mold typically takes four to eight weeks, and costs anywhere from $2,000
to $100,000+ depending on the shape and the complexity of the part. Due to these high costs,
manufacturers are looking at ways to minimize the cost of custom tool production and reduce
lead times to bring products to the market faster.
Desktop 3D printing is a powerful solution to fabricate injection molds rapidly and at low cost. It
requires very limited equipment, saving CNC time and skilled operators for other high-value tasks
in the meantime. Manufacturers can benefit from the speed and flexibility of in-house 3D printing
to create the mold and couple it with the production force of injection molding to deliver a series
of units from common thermoplastics in a matter of days. They can even achieve complicated
mold shapes that would be difficult to manufacture traditionally, enabling development teams to
be more innovative. Furthemore, product development benefits from the ability to iterate on the
design before investing in hard tooling.
Even though 3D printing molds can offer these advantages when used appropriately, there are
still some limitations. We should not expect the same performance from a 3D printing polymer
mold as from a machined metallic one. Critical dimensions are harder to meet, cooling time is
longer because the thermal transfer occurs slower in plastic, and printed molds can easily break
under heat and pressure. However, some companies managed to produce series of hundreds of
parts with printed molds and even thousands of shots for very simple designs. Low-run injection
molds are great assets for engineers to deliver limited batches of end-use parts or prototypes in
the final plastic, for pre-production tests.
FAST FABRICATION OF SHORT-RUN INJECTION MOLDS
Stereolithography (SLA) printing technology is a great choice for molding. It is characterized by a
smooth surface finish and high precision that the mold will transfer to the final part and that also
facilitates demolding. 3D prints produced by SLA are chemically bonded such that they are fully
dense and isotropic, producing functional molds at a quality not possible with fused deposition
modeling (FDM). Desktop SLA printers, like those offered by Formlabs, simplify workflow as they
are easy to implement, operate, and maintain.
FORMLABS: Low-Volume Rapid Injection Molding With 3D Printed Molds 3
