Most 3D printers use a soluble structural material. This material can be removed with a solvent or chipped away. Cores printed from soluble material can be used in lost-wax casting applications. Soluble material can also be used as the master for open-molding processes such as spray or hand lay-up. For open-molding processes, print a soluble master slightly smaller than the desired part and layer the master with materials like fiberglass and resins. After the materials are cured, the soluble material can be removed.

Machined tooling contributes to the majority of production costs for many small-run jobs. 3D printing can reduce the cost of plastic cores, molds, and tooling, but there are several considerations to examine before choosing this route. Patrick Gannon, engineering manager at Rapid Prototype + Manufacturing LLC, Avon Lake, Ohio, offers a few tips on how and when to 3D print plastic molds and tooling.

“What we do know is that 3D printing plastic molds adds value because most machining operations can be eliminated. It’s not uncommon for a machined tool to cost $45,000 and take six to eight weeks to complete. The same mold, 3D printed, will cost about $2,000 and is made in a matter of hours to one week. Printed plastic molds are great for jobs producing 500 parts or less, and for jobs that use complex tooling. But remember, as with any 3D printing project, the best approach is to expect less-than-perfect results. And, if you have to make multiple versions of the tool, you begin to lose the benefits.”

After converting the model into an STL file, upload the file to the software that works with the printer. Choose the resolution, material, and machine that will print the mold. Different systems allow more or fewer adjustments to the build specifications, but the program does most of the work at that point. Set the printer up with the material and (in some machines) the tip to be used. Check for any calibration and cleaning needed, and then start printing. Remove the mold and clean off support material — polish the mold as needed. Plastic molds fit the same as machined molds, so they can be directly inserted into most process machines. But depending on the tool and part, you might need to create a metal box around the plastic to hold it together.fri

During this timeframe, the demand for HDPE in the US market exhibited bullish tendencies, with prices rise of 2% for Injection molding grade FOB Texas(USA). Trading activities remained robust, with market participants actively engaging in spot market transactions amidst constrained availability. The upward trajectory of HDPE prices can be further attributed to the heightened costs of feedstock Ethylene and upstream Naphtha, exerting increased cost pressures on the product. Moreover, the surge in export demand, propelled by ongoing logistical challenges, provided producers with additional opportunities to sell their products at elevated prices. Consequently, this heightened export activity facilitated the reduction of excess resin from the domestic market, resulting in tightened domestic supplies and upward pressure on domestic HDPE prices. This overall escalation in HDPE prices aligns with anticipated trends, as international resin prices have strengthened concurrently with the rise in freight costs. The recent uptick in PE spot prices throughout the month has encouraged producers to advocate for another price increase in February, following a successful hike implemented in January.

No matter the material — the printed mold, core, or tooling must withstand higher heat than the injected, dipped, poured, sprayed, or hand-layed material. If the print will be exposed to high temperatures, one recommendation is PPSF/PPSU. If the print needs to be certified for flame, smoke, and toxicity, then Ultem would be the material of choice. If the process will apply pressure on the print, polycarbonate acrylonitrile-butadiene-styrene (PC-ABS) can be used because it has the highest impact resistance. And, ABS-M30i or PC-ISO is suitable for processes that need to use material that is ISO-10993 certified. All of these materials work with fused-deposition-modeling (FDM) printing machines.

3D printed mold design is similar to metal molds. Mounting holes can be modeled in the same pattern as a metal mold.  And, if overmolding or dual material injecting is desired, the design mimics metal molds. However, printed design changes when heat transfer is an issue. Plastic molds transfer heat poorly so to help move heat, add several holes to the mold to help cool injected parts quicker. Another method is to insert copper or other heat-transfer materials into the holes.

High Density Polyethylene (HDPE) Market Analysis: Plant Capacity, Production, Process, Technology, Operating Efficiency, Demand & Supply, End-Use, Grade, Foreign Trade, Sales Channel, Regional Demand, Company Share, Manufacturing Process, 2015-2035

In the initial half of February 2024, High-Density Polyethylene (HDPE) experienced an upward price trajectory across Europe and the United States, primarily driven by supply shortages and a surge in demand from the market. In Europe, the upswing in HDPE prices was mainly attributed to constrained supplies coupled with delayed cargo. Meanwhile, in the US, HDPE prices surged due to heightened demand from downstream industries such as construction and packaging. Further, the rising prices of feedstock Ethylene and upstream Naphtha and Crude oil have had a significant impact on the production costs of HDPE in both regions, contributing to the upward pressure on prices. Furthermore, supply disruptions in key transportation routes like the Panama Canal and the Red Sea have also played a role in influencing the pricing dynamics of the product, adding to the market volatility experienced during this period.

Printed molds, tooling, and cores may require different materials. And, material choice will continue to vary by the process and application. For instance, an injection mold will need high-heat and chemical-resistant material. Ultem of polyphenolsulfone (PPSF/PPSU) satisfies those specifications.

The HDPE market in Europe witnessed a price increase of 2% for Injection grade FD Hamburg(Germany), primarily fueled by constrained supplies stemming from delayed cargo arrivals from the Middle East and limited material quantities from the US. This upward trend was further reinforced by reduced output rates and regional outages. Despite this, overall demand remained relatively stable, marked by subdued activity within end-user industries. Further, market participants in the European market faced significant price hikes in February offers from local producers, despite only a marginal increase in feedstock Ethylene prices. The scarcity of import options and reduced allocations compelled suppliers to prioritize margin expansion, particularly after enduring negative margins for several months. With the February ethylene settlement showing a modest uptick due to sluggish demand in January, the substantial price hikes sought by HDPE suppliers in February will significantly aid them in reclaiming the margins lost over the past few months. Meanwhile, market players are directing their attention toward March, primarily engaging in discussions centered around potential Ethylene contract price settlements for the upcoming month.

Lindsey has been an Associate Editor for Machine Design since 2012. She holds a Bachelor of Science in mechanical engineering from Cleveland State University. Prior to joining Penton, she worked in product design, packaging, development and strategy, and manufacturing. She covers the materials market and other areas of interest for design engineers such as 3D printing and methods to operate efficiently.

Tolerance must be taken into account when designing a mold. This means opening up gaps and realizing that you will never get extremely tight tolerances. If extreme tolerances are needed, a printed mold will not be acceptable right off the printer — even after postmachining.

In the initial half of February 2024, High-Density Polyethylene (HDPE) experienced an upward price trajectory across Europe and the United States, primarily driven by supply shortages and a surge in demand from the market. In Europe, the upswing in HDPE prices was mainly attributed to constrained supplies coupled with delayed cargo. Meanwhile, in the US, HDPE prices surged due to heightened demand from downstream industries such as construction and packaging. Further, the rising prices of feedstock Ethylene and upstream Naphtha and Crude oil have had a significant impact on the production costs of HDPE in both regions, contributing to the upward pressure on prices. Furthermore, supply disruptions in key transportation routes like the Panama Canal and the Red Sea have also played a role in influencing the pricing dynamics of the product, adding to the market volatility experienced during this period. During this timeframe, the demand for HDPE in the US market exhibited bullish tendencies, with prices rise of 2% for Injection molding grade FOB Texas(USA). Trading activities remained robust, with market participants actively engaging in spot market transactions amidst constrained availability. The upward trajectory of HDPE prices can be further attributed to the heightened costs of feedstock Ethylene and upstream Naphtha, exerting increased cost pressures on the product. Moreover, the surge in export demand, propelled by ongoing logistical challenges, provided producers with additional opportunities to sell their products at elevated prices. Consequently, this heightened export activity facilitated the reduction of excess resin from the domestic market, resulting in tightened domestic supplies and upward pressure on domestic HDPE prices. This overall escalation in HDPE prices aligns with anticipated trends, as international resin prices have strengthened concurrently with the rise in freight costs. The recent uptick in PE spot prices throughout the month has encouraged producers to advocate for another price increase in February, following a successful hike implemented in January. The HDPE market in Europe witnessed a price increase of 2% for Injection grade FD Hamburg(Germany), primarily fueled by constrained supplies stemming from delayed cargo arrivals from the Middle East and limited material quantities from the US. This upward trend was further reinforced by reduced output rates and regional outages. Despite this, overall demand remained relatively stable, marked by subdued activity within end-user industries. Further, market participants in the European market faced significant price hikes in February offers from local producers, despite only a marginal increase in feedstock Ethylene prices. The scarcity of import options and reduced allocations compelled suppliers to prioritize margin expansion, particularly after enduring negative margins for several months. With the February ethylene settlement showing a modest uptick due to sluggish demand in January, the substantial price hikes sought by HDPE suppliers in February will significantly aid them in reclaiming the margins lost over the past few months. Meanwhile, market players are directing their attention toward March, primarily engaging in discussions centered around potential Ethylene contract price settlements for the upcoming month.

Printed plastic molds can be used in injection, extrusion, and blow-molding processes. Printed tooling can be used in vacuum-forming, thermoforming, and drape-forming processes. In thermoforming applications, for example, printed tooling can make blister packaging for consumer products. Tooling for packaging development may require multiple cavities and, with each cavity, there might be thousands of vent holes. Printing cuts the time and cost spent to drill or CNC those holes.

Cores used to make molds can also be printed. For instance, a printed part can act as the core to make silicone molds. Cores are traditionally machined from plastic, wood, or metal depending on the tolerance needed and the surrounding temperature. Even though printed cores may require sanding to get a smooth finish, costs are lower than a core requiring several machining processes.

“There’s no doubt — printing individual and identical prototypes and end-use parts isn’t the right choice for large-quantity jobs and jobs that needed to be done yesterday,” says Gannon.