Compressed air is used as the power source to push the ejection mechanism to move. Pneumatic ejection is accomplished by compressed air, which blows the plastic product directly out through many tiny holes in the molding mold. This ejection method does not leave any ejection marks on the surface of the product but requires the addition of pneumatic auxiliary equipment.

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High Temp Resin offers a heat deflection temperature is 238 °C @ 0.45 MPa that is suitable for injection molding. This material is more brittle, but is recommended for materials with a high molding temperature and to reduce cooling time.

This is the most common ejection method, which uses mechanical devices (such as ejector pins, ejector pins, etc.) to push the molded plastic parts out of the mold. The ejector rod is fixed on the frame and does not move. When the mold is opened, the movable template moves back. The ejector rod passes through the center hole of the movable template and acts on the top plate of the mold, pushing the top plate to eject the product out of the mold. The length of the ejector rod is determined by the thickness of the mold and can be adjusted by the thread.

Now that you’ve designed and 3D printed your mold, you can mold the parts on your benchtop plastic injection molding machine.

In addition, the ejector stroke also has the function of limit protection, which is used to limit the distance of the ejector forward and backward to ensure smooth de-moulding of the product and accurate reset of the ejector. For some specially designed molds, such as molds with secondary ejection mechanisms, the total ejector stroke must be greater than the first ejector stroke to ensure that the inclined ejector is completely separated from the undercut part and the core pulling action is completed.

If you have more questions about the workflow, make make sure to check our article FAQ: Injection Molding With 3D Printed Molds.

Want to learn more about injection molding with 3D printed molds? Download our white paper for detailed guidelines for using 3D printed molds in the injection molding process and see real-life case studies with Braskem, Holimaker, and Novus Applications.

Grey Pro Resin has a lower thermal conductivity than High Temp Resin or Rigid Resin, which leads to a longer cooling time, but it is softer and can wear hundreds of cycles.

When selecting an injection molding machine, the ejector stroke should be reasonably selected according to the appearance of the product and the design structure of the mold. Generally, the maximum ejector stroke of the machine is fixed, and the user can adjust it according to the specific product when using it. When ordering a machine, the ejector stroke should be large so as to be suitable for the molding of more products. For example, the ejector stroke of the Haichen HCK110 injection molding machine is 110mm.

Turn the visibility of your current mold core off, and turn the other side on. Repeat the process to ensure that the object fully intersects with the inlet of the other half of the mold core. With your object lined up, you’re ready to subtract the area of two intersecting objects by using the “boolean difference” function in Blender.

Setting up the print only takes a few seconds in PreForm, the print preparation software for Formlabs 3D printers. If your mold design requires support structures for printing, make sure to orient the mold halves in PreForm so that the cavity faces up. This will simplify post-processing and ensure a high-quality surface for your molded parts.

Your mold is now ready for printing. Export each half, making sure to check the “Selection Only” box in the Blender exporter.

The application of the secondary ejection mechanism shows that by reasonably setting the ejection stroke, the overall structure of the mold can be simpler, safer, and more reliable to use, and meet the automation needs of mass production.

The ejector stroke is the maximum distance the ejector moves forward to eject the plastic part, usually from 110mm-450mm.

Based on internal testing and case studies with our customers, we suggest to choose the 3D printing resin based on the criteria from the table below. Three stars means the resin is highly effective, one star is less effective.

Before purchase, make sure to evaluate the injection molder carefully against your production requirements. For large parts, industrial processes will still be necessary. This DIY injection molding technique is best optimized for producing small parts at low volumes.

Specifically, the ejector stroke determines whether the plastic part can be de-molded smoothly. For example, a long plastic part requires a longer ejector stroke, while a short plastic part can use a shorter ejector stroke. When purchasing an injection molding machine, it is usually recommended to choose a larger ejector stroke to accommodate a wider variety of products.

In Blender, use the eye icon in the scene explorer to toggle off one half of the mold. Once your workspace is set up to your liking, set both halves of the mold to the “wire” draw type under the Object menu, as in the image below.

Creating custom molds using a stereolithography (SLA) 3D printer, like the Form 3, is simple and convenient, allowing you to leverage the benefits of both 3D printing and traditional molding techniques.

For inclined roof structures, the calculation of the ejection stroke H needs to take into account the angle of the inclined roof and the horizontal stroke.

The conversation around 3D printing and injection molding is often oppositional, but it’s not always a question of one versus the other. By directly 3D printing parts or using 3D printed molds for injection molding for prototyping and low-volume production, you can leverage the benefits of both technologies. This will make your manufacturing process more time- and cost-efficient and allow you to bring products to the market faster.

If the ejection device stroke is insufficient, the plastic parts will not be able to completely detach from the mold, thus affecting production efficiency and product quality. By increasing the ejector stroke, it can be ensured that the plastic parts can be completely detached from the mold after the mold is opened, avoiding product defects or manual intervention caused by insufficient ejection.

there is an ejector cylinder installed behind the movable template, which pushes the piston, that is, the ejector rod, to work. There are bolts on the piston to adjust the length of the ejector rod. When the mold is opened, the template moves backward and the ejector cylinder pushes the ejector rod to extend. The ejection force, speed, time, and stroke are adjusted by the hydraulic system, which can be reset automatically and can eject the product during or after the mold opening process, which is conducive to shortening the injection molding cycle.

Select the first half of your object, and choose the boolean option under the Modifiers Menu. Select the object you’re cutting, and make sure that the “difference” operation is selected. Apply the operator, and do the same for the other side. It should look something like the image below. If you get stuck here, this tutorial on adding interlocking components to a design may be helpful.

In some cases, a short ejector stroke may cause the product to warp or deform during demolding. By adjusting the ejector stroke, the demolding speed and force of the product can be better controlled, thereby reducing the risk of product damage.

Adding two to five degrees of draft on surfaces perpendicular to the direction of pull will allow the part to be removed more easily and will minimize degradation of the mold.

In this guide, we’ll walk you through the process of DIY injection molding and share all the tools and tips necessary to utilize plastic injection molding in-house using 3D printed molds.

According to the calculation of the stroke of the double-action flange ejector, the stroke distribution of the vertical flange and the side flange needs to be considered to ensure smooth ejection.

The exact approach to DIY injection molding will vary based on your desired design and volume, but these tips and tricks will help increase your success rate.

Ejector stroke H is usually equal to the product height L plus a safety margin (5~10mm). That is, H=L+(5~10mm). Here L is the distance from the highest point to the lowest point of the product in the mold opening direction.

The ejection mechanism is pushed by the hydraulic system, which is suitable for situations where a large thrust is required.

A benchtop injection-molding machine, such as the Galomb Model-B100 or the Holipress. There are a number of benchtop injection molders on the market that vary in cost. Many of the lower cost molders use a hand-driven plunger, while some of the more expensive units use a screw or pneumatic system. Some of our customers have recommended systems from Minijector, Morgan, APSX, or Micromolder as well. Desktop automated molders such as the product line from Babyplast are good alternatives for mass production of small parts.

Depending on the geometry and the size, multiple molds can be printed at once on a build platform to increase printing efficiency.

Consider the desired properties of your object and the capabilities of your injection molder before you make your choice. From there, simply follow the bespoke instructions on your injection molder to quickly and efficiently produce your parts.

To reduce the visibility of print lines on the finished part, print the mold with a smaller layer height (50 or 25 microns per layer instead of the default 100). Note that this increases print time.

S is the horizontal stroke of the inclined top, S1 is the downward stroke of the inclined top, X is the angle of the inclined top, Y is the downward angle of the inclined top

According to the calculation of the mold slider stroke, the undercut distance and safety distance need to be considered to ensure that the product will not interfere with the slider when ejected.

In addition, the ejector stroke is closely related to other technical parameters such as ejector force and ejector speed. The ejector force refers to the maximum thrust of the ejector device, while the ejector speed refers to the speed at which the ejector device moves. These parameters work together to ensure that the plastic part can be removed from the mold safely and effectively.

First, pick the CAD software tool of your preference to design the mold insert. We’ll use the open-source Blender, but the workflow should be fairly similar in any other CAD software.

You have a wide variety of materials to choose from for injection molding. Formlabs and our customers have tested the following materials with 3D printed injection molds:

According to the mold, the ejection stroke is determined according to the ejection stroke required by the product. Usually, there is a certain safety margin more than the ejection stroke required by the product to ensure that the product can be removed smoothly.

A 3D printing material that can withstand the temperature and pressure on the mold during the injection molding process. We recommend the following materials for Formlabs SLA 3D printers:

Injection molding is ubiquitous as a manufacturing process—in fact, the majority of plastic products in the world today are manufactured by injection molding. While it is an ideal technique for large-scale production needs, traditional CNC machined metal molds have prohibitive high costs and long lead times for low-volume production.

If designing for an aluminum mold frame, add .125 mm of extra thickness to the back of the mold plates to account for compression forces and to ensure a complete seal.

The main function of the ejector stroke of the injection molding machine is to ensure smooth demolding of the product, protect the mold and the product, adapt to the needs of different products, improve production efficiency, and extend the service life of the mold.

Interested in other applications of 3D printed molds? Download our white paper that also covers thermoforming and casting with elastomers.

Extending the ejector stroke does not require changing the internal structure of the mold, which reduces the production cost, and the extended ejection stroke can be accurately controlled by setting a scale, thereby improving the demolding efficiency.

To 3D print the mold, it’s essential to pick a material that can withstand the temperature and pressure on the mold during the injection molding process.

Building a setup for DIY injection molding does require some investment. It takes both money and time to acquire the right equipment and to master using it. However, these costs are in many cases still lower than the cost of a single metal mold, so the eventual time and cost savings, once you’re up and running, will easily offset the initial effort.

A high-performance desktop SLA 3D printer, like the Formlabs’ Form 3. The Form 3 can produce accurate molds with crisp features, and a smooth surface finish that will yield high-quality final molded parts. Beyond DIY injection molding, an SLA 3D printer is also a valuable asset for prototyping and other applications throughout product development.

It is to ensure that the molded product can be smoothly separated from the mold so that the next mold action can continue. Only effective ejection force and ejector stroke can make the molded product finally smoothly separate from the mold.

Rigid 10K Resin is an industrial-grade, highly glass-filled material, which provides a solution that can cope with a wider variety of geometries and injection molding processes. It has an HDT of 218°C @ 0.45 MPa and a tensile modulus of 10,000 MPa, making it strong, extremely stiff, and thermally stable.

Download our white paper for guidelines for using 3D printed molds in the injection molding process to lower costs and lead time and see real-life case studies with Braskem, Holimaker, and Novus Applications.

For some plastic parts with complex structures, such as products with deep depressions in the middle, a longer ejector stroke may be required to achieve smooth demolding. By optimizing the ejection stroke, the mold design can be simplified, the product appearance can be protected, and the requirements for the injection molding machine stroke can be reduced.

For prototyping and low-volume production (approximately 10-1000 parts), 3D printed injection molds provide a time- and cost-efficient solution. They also enable a more agile manufacturing approach, allowing engineers and designers to test mold designs, easily modify them, and then continue to iterate on their designs much faster, while being orders of magnitude cheaper than traditional CNC machining.

Now, you can position your mold. Ensure that the object fully intersects with the inlet for the molten plastic during the injection molding process. Use orthographic mode, engaged via “toggle perspective/ortho,” to make this more straightforward.

Depending on the injected material, adhesion of the part to the mold can cause deterioration of the mold during extraction, in particular with flexible materials such as TPUs or TPEs. Using a mold release agent is a good solution to help separate the part from the mold. Silicone mold release agents are compatible with Formlabs Grey Pro Resin, High Temp Resin, and Rigid 10K Resin.

Download the blank mold insert design files—you’ll use them to create your injection mold design. The designs can also be easily scaled to accommodate most injection molders and mold frames. Alternatively, you can also design your own mold insert for the using the cavity diagrams of the master mold frames.