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Introduction to Metal Casting and Ways to Combine 3D Printing With Casting Workflows
Metal casting is an age-old metalworking process in which molten metal cools and solidifies in a mold to form metal parts. Despite its ancient roots, metal casting is still one of the most popular processes for companies looking to produce metal parts.
This article will cover what metal casting is, how it works, and walks you through the most common metal casting processes and the benefits manufacturers can attain by combining modern digital tools like 3D printing with traditional casting workflows.
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Metal casting step-by-step from the original design through final casting.
Since the advent of metal casting, the methods have evolved and varied. Its core techniques, however, have remained constant. Here is a general step-by-step process for metal casting:
Ring patterns 3D printed in Castable Wax 40 Resin.
In order to begin the metal casting process, a manufacturer first must develop a representation of the desired pattern. This pattern is essential in designing the mold used for the cast. It is traditionally made from wood, foam, plastic, or wax and ensures that the mold accurately produces the finished metal part. Today, 3D printing is also a common method to produce patterns, which allows designers to create accurate patterns directly from digital CAD software tools.
A pattern is not an exact replica of the desired part. It has additional elements that make the casting process possible, including gates that allow molten metal to flow at a steady rate and vents for gas to escape. Additionally, patterns are also larger than the parts they represent to account for the shrinkage that occurs during cooling.
When the casting piece is hollow, the manufacturer also creates a core of sand or metal to shape the internal form.
This core gets removed upon completion of the casting.
The next step is creating a casting mold, which can be either reusable (non-expendable) or non-reusable (expendable). Non-reusable molds are usually made out of sand, plaster, wax, or by 3D printing, and just as the name suggests, they get destroyed in the casting process. Reusable molds are made out of metal and other durable materials and can be reused for multiple casting cycles.
Ceramic shells after burnout and 3D printed patterns in Clear Resin.
Molten pewter poured into a High Temp Resin 3D printed mold for metal casting.
During this step, the metal gets heated in a furnace until it melts. Depending on the application, manufacturers can use a variety of different metals, with the most commonly cast metals being iron, aluminum, aluminum alloy, steel, copper, and zinc, as well as precious metals like gold and silver. Once the metal melts, the manufacturer pours it into the mold cavity and allows it to cool and solidify.
Metal casting post-production.
Once the metal cools down and solidifies, the parts get removed from the mold. Depending on the mold type, this can be done by vibrations in a shakeout process, washing away the investment material, or by ejector pins. Then, excess material, such as vents, gates, and feeders, are removed from the parts. Finally, the parts get filed, grated, machined, or sandblasted to smooth the surface and reach the final shape requirements.
Though all metal casting techniques share the same core process, there are various methods better suited for different applications. Some of the most common methods include die casting, investment casting, and sand casting.
Die casting uses a steel mold and high pressure. (Source: buhlergroup.com)
Die casting is a metal casting process in which a manufacturer pushes molten metal into a steel mold cavity at a high pressure to quickly produce metal parts. In die casting, the manufacturer fixes two halves of a die or reusable mold together and uses a nozzle to inject pressurized molten metal into the die.
When the metal cools, the die opens, and ejector pins push out the cast.
The two most common die casting processes are hot-chamber and cold-chamber casting. While the specifics of these processes vary, there are several shared characteristics of the die casting process as a whole.
Hot-chamber die casting is the most common of the two main die casting processes. Hot-chamber die casting machines have a built-in furnace to heat the metal within the machine. Once the metal reaches a molten state, the machine lowers a cylindrical chamber into the molten metal. The gooseneck shape of the metal injection system allows the chamber to quickly fill itself, and then push the material into the mold with air pressure or a piston.
Immersing the injection mechanism to fill it allows for rapid and streamlined mold injection in this casting process. Because the chamber is subject to direct heat from the molten metal, however, hot-chamber die casting systems are at risk for corrosion, making them a less viable option for metals with high melting points.
Instead, it is better suited for materials with low melting points and high fluidity, like lead, magnesium, zinc, and copper.
By contrast, the cold-chamber die casting process works more slowly to avoid corrosion. With this method, a foundry worker ladles molten metal into the injection system. A piston then pushes the metal into the mold.
This process limits the corrosion that is more common in hot-chamber die casting. It is an ideal option for metals with high melting points, like aluminum and aluminum alloy.
The die casting process is rapid and produces highly detailed parts. It is ideal for the production of high volumes of complex parts and can also produce strong parts with smooth surface finishes. Die casting’s capacity to produce a high volume of parts makes it a crucial process in the automotive and aerospace industries.
As die casting tooling and equipment are expensive, this process is not cost-effective for smaller production runs. In addition, the malleability of metals used in the process can impact the complexity of the product.
Cast parts from SLA patterns printed in Clear Resin on a Formlabs 3D printer.
Investment casting, also known as lost-wax casting, is a process that uses wax, slurry, and molds to produce complex parts. It is one of the oldest metal casting techniques but is still valued for its ability to create precise metal parts with intricate shapes.
This process is still widely used for producing jewelry, dentistry, and art. Its industrial form, investment casting, is a common way to create precision metal parts in engineering and manufacturing.
Investment casting patterns are typically made out of wax or 3D printed polymers. The patterns are assembled into a tree-like structure and dipped into a slurry of silica, or put into a flask and surrounded by the liquid investment plaster. After the investment material dries, the flask is placed upside down into a kiln, which melts the pattern, leaving a negative cavity in the shape of the original model. Metal is melted and then poured, using gravity or vacuum pressure to pull the metal into the cavity.
The casted parts are filed, ground, machined, or sandblasted to achieve final geometry and surface finish.
Sprue trees with cast rings.
Investment casting is a versatile process. It allows manufacturers to produce accurate and repeatable parts out of nearly any metal available for casting and complicated shapes that would be difficult or impossible with other casting methods. Casted parts also have excellent surface qualities and low tolerances, with minimal surface finishing or machining required.
These features make investment casting ideal for complex parts in automotive, aerospace, and industrial applications, medical tools, dental implants, as well as fine jewelry and art.
Investment casting is a complex and labor-intensive process. It requires specialized equipment, costly refractories and binders, as well many manual operations to make a mold. It can be difficult to cast parts that require cores and the process is better suited to small parts.
One half of a sand casting mold.
Sand casting is a metal casting method that was first in use 3,000 years ago but remains the most widely used casting method to this day. This process allows manufacturers to cast metal without relying on machining.
In the sand casting process, the manufacturer first creates a foundry pattern, or replica of the casting, most commonly from wood or plastic. The pattern is oversized to allow for shrinkage. Parts with features on one side only require an open-faced mold. For parts with multiple detailed surfaces, the manufacturer separates the foundry pattern into two mold boxes to form a closed cavity mold. The top half is called a cope and the bottom a drag.
Once the manufacturer creates the pattern, they tightly pack sand around the pattern. Then, they add sprues and gates to ensure that the molten metal flows smoothly through the mold cavity. The manufacturer removes the pattern then clamps the two halves of the sand mold together. Once the metal melts to a molten state, it is poured into the mold and left to cool.
From here, the sand mold is removed using vibrations or high-pressure water. Finally, the manufacturer refines the part by removing sprues and gates, and polishing the cast metal part.
Sand casting is an adaptable process that functions outside the limitations of machinery. Because of this, it can create complex parts of virtually any size. Sand is inexpensive and plentiful, which lowers the setup cost and makes modifications possible. It is the only practical or economical way to produce very large castings. The lead time of sand casting is also short, making it a viable process for short production runs.
Sand casting’s versatility makes it a manufacturing option across a wide array of industries. It can produce medical equipment, automobile parts, electronic equipment, gas tanks, and engine blocks, and more.
Sand casting creates highly porous, textured metals. The shrinkage and rough surface finish also lower the dimensional accuracy of parts. This results in a low-strength final product that requires time-consuming post-processing to achieve a higher quality finish.
In order to choose the right industrial metal casting process, several factors must be considered. We’ve created this comparison table to help you compare die casting, investment casting, and sand casting in terms of types of metals, production volume, costs, production time, part complexity, and for which industries they are generally used.
| Die Casting | Investment Casting | Sand Casting | |
|---|---|---|---|
| Compatible metals | Aluminum, copper, lead, magnesium, zinc | Most metals | Most metals |
| Production volume | High volume | Low to high volume | One-off to medium volume |
| Unit costs | Low | Moderate to high | Moderate |
| Tooling costs | High | Moderate | Low |
| Cycle time | Rapid | Long | Moderate |
| Industries | Automotive, aerospace, consumer products, furniture, power tools | Automotive, aerospace, jewelry, medicine, dentistry, art | Automotive, aerospace, industrial equipment, electronics, consumer products |
3D printed jewelry ring pattern and cast metal part.
Engineers, designers, jewelers, and hobbyists can capitalize on the speed and flexibility of 3D printing by combining castings processes like indirect investment casting, direct investment casting, pewter casting, and sand casting with 3D printed patterns or casting metal into 3D printed molds. Cast metal parts using 3D printed rapid tooling can be produced in a fraction of the time invested in traditional casting and at a significantly lower cost than metal 3D printing.
Stereolithography (SLA) 3D printers offer high precision and a broad material library that is well-suited for casting workflows and can produce metal parts at a lower cost, with greater design freedom, and in less time than traditional methods.
Webinar
In this webinar, we will look at how desktop stereolithography (SLA) 3D printers are being used to directly print patterns, how to work with SLA patterns for investment casting, and how the benefits of generative design are increasing the demand for printed patterns.
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A 3D printed mold in Clear Resin for wax injection.
The process of making patterns from molds or tooling is referred to as indirect investment casting because it requires creating molds for producing the patterns in addition to final investment molds.
Rigid molds for wax (often referred to as tools) are commonly fabricated by machining aluminum or steel. Machined metal molds cost thousands of dollars to produce and take weeks of machining and polishing work before first shots can be run and pattern parts evaluated within a casting process.
With 3D printing, manufacturers can directly 3D print the mold for their pattern using materials like High Temp Resin or Rigid 10K Resin, resins with high-temperature resistance. For an optimal surface finish of molded parts, treat the interior surfaces of the mold by sanding and polishing for a smooth look, or bead blasting if a uniform matte look is desired. To ensure the final cast parts are dimensionally accurate, compensate for shrinkage by scaling up the printed mold.
The exact shrinkage of the wax and the casting process can be obtained from supplier specifications.
3D printed molds for metal casting shorten the time between concept and first tests to a matter of days because manufacturers can directly print the tooling necessary for running and evaluating parts.
While molded pieces must follow design rules for moldability (e.g., no undercuts, draft is beneficial, etc.), you can achieve increased pattern complexity by using assembly jigs to combine multiple components into a single structure.
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3D printed jewelry patterns and metal casted rings.
Direct investment casting is a version of investment casting where the process moves directly from pattern creation to surrounding the pattern with investment material.
It is ideal for producing parts with geometries that are too complex to be molded or for parts with extensive undercuts and fine surface texture details, where molding is possible but carries high tooling costs.
Traditionally, patterns for direct investment casting are carved by hand or machined if the part is a one-off or expected to be only a handful of units. With 3D printing, however, manufacturers can directly print the patterns, removing the design and time constraints common in other processes.
With 3D printing, engineers, designers, and jewelers can direct 3D print patterns in order to achieve shorter lead times and geometric freedom that exceeds the design for manufacturability constraints of molding processes. Formlabs developed a range of castable materials suitable for direct investment casting, in particular for the jewelry industry.
White Paper
The way jewelers work is changing, and castable photopolymer resins are leading the way.
In this guide, learn how to cast fine jewelry pieces 3D printed on Formlabs printers.
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Sample part
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Grey Resin printed pattern and finished aluminum casting from an open-faced sand mold.
Similar to investment casting, 3D printing can be used to create patterns for sand casting.
In comparison to traditional materials like wood, 3D printing allows manufacturers to create complex shapes and go straight from digital design to casting.
Metal Miniatures made with pewter casting and 3D printing.
Pewter is a malleable metal alloy with a low melting point that can be used for making fully metal objects for decorative applications such as detailed metal miniatures, jewelry, scale models, and replicas of antiques.
With recent developments in temperature-resistant 3D printing materials, like High Temp Resin for Formlabs SLA 3D printers, it’s now possible to 3D print molds for direct pewter casting.
There are two options for mold designs: a sacrificial or pull-apart mold. In a sacrificial mold, there is a shell designed to be broken apart in the process. Pull-apart molds function with separate halves so the mold can be reused.
Compared to directly printing metal, the casting pewter in 3D printed molds offers significantly better detail and surface finish at a small fraction of the cost. Compared to wax casting, directly 3D printing a mold has fewer steps and requires less manual effort, while preserving the most possible detail.
Webinar
Watch our webinar to learn how moldmaking using 3D printed masters and reusable or sacrificial molds can allow you to produce parts in porcelain, precious and non-precious metals, silicone and biocompatible flexible materials, and more.
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Jewelry investment casting process with 3D printed patterns.
Businesses looking to boost design freedom or cut costs and lead times have a strong solution in metal casting with 3D printing.
Certain types of complex metal castings, such as large shapes with cross-sections and pieces with multiple cores, are difficult to create using traditional metal casting methods. 3D printing allows manufacturers to produce these complex designs. For example, jewelers can create intricate and custom designs that might be impossible without a 3D printed pattern.
3D printing also eliminates reliance on multiple machines or service providers to create parts. Instead, companies just need a digital file, a 3D printer, and printing material. This can cut costs and waste, as all the material used goes into the final product.
Finally, the combination of 3D printing with metal casting can cut costs and lead time.
Rather than waiting weeks for expensive tooling before being able to cast a final product, a 3D printer can create a pattern or mold in hours.
Metal casting combined with 3D printing help companies quickly and efficiently create metal parts. With a Formlabs SLA 3D printer, you can expedite the metal casting process and cut costs along the way.
Learn more about the Form 3 desktop SLA 3D printer and request a free sample part to evaluate the quality firsthand.
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Ultimate Guide to Silicone Molding for 3D Printing (Part 1)
Download the full Guide
as a PDF!
The simple post-processing techniques presented in this guide are an excellent way for professionals to create low-cost silicone molds, threaded inserts for enclosures, vacuum formed parts, and more.
Silicone molding is a powerful production method that, when combined with 3D printing, can allow you to make several copies of one product. You can also create a product in a material that is not supported by your 3D printer.
In this How To, we will show you some of the best practices associated with creating silicone molds around 3D printed parts.
Working time will vary depending on a number of factors. Creating a mold around our 3D printed part took us about 1.5 hours. Casting into our mold took about 15 minutes.
Supplies
3D printed mold box, hardware, vents & keys (read on for more info).
Master (the print you are molding)
Silicone
Resin and dye
Mixing cups
Mixing sticks
Mold release spray
Hot glue or cyanoacrylate glue
Funnel
Ex acto knife
Rubber bands, tape, or straps
Gloves
Respiratory mask
Eye protection
Need some of these products? We've curated an Amazon wish list for you.
Step 1: Choose a file to cast a mold around
Obtain a file that you would like to either make several of, or create in a material not supported by your printer.
We chose the cap to a perfume bottle to understand what the process would look like for a product development team attempting to produce several concept models of a prototype.
The next step is to create your mold box. This is the structure that will hold the silicone in place around your part when pouring. Your master will need to be suspended in this structure.
You can create mold boxes from:
Foam core board
Legos
3D printing
We chose to design and print ours as this method has a few benefits. Designing and 3D printing mold boxes allows you to:
Print in pour holes and vents
Easily calculate the volume of our mold
Create boxes that perfectly fit the parts you plan to create a mold of
Re-use mold boxes to create multiple molds
While 3D printing your mold box isn’t necessary, it provides you with a reusable customizable mold box that the other methods cannot produce.
Step 3: Prepare and Print
Because the silicone molding process is not very demanding on the 3D printed mold box or master, you can select standard print settings.
The 2021 Guide to 3D Printing Materials
Learn about polymers, composites, and metals all available for 3D Printing!
Supplies Used:
3D printed mold box, 3D printed master, Cyanoacrylate glue, Mold release spray, Vents & Keys
A: Spray your mold box, master, vents, and keys with mold release.
B: Choose points across model to glue vents
C: With our 3D printed mold box we were able to glue our master directly onto the pour hole during preparation.
D: Spray again with mold release for good measure
You can suspend your master using popsicle sticks, skewers, or 3D printed rods glued to the surface of the master in an inconspicuous place. The holes left in their place after your mold has cured will aid in resin flow through the mold.
Step 5: Open Bottles of Silicone (Parts A and B) and Stir Thoroughly
Supplies Used: Silicone (Part A & B), Mixing Sticks
As silicone comes in two parts, it needs to be mixed both individually and once combined with its hardener.
Mix slowly using separate mixing sticks.
Supplies Used: Measuring cups
A: Determine the volume of silicone needed to fill your mold
B: Measure desired amount of silicone and hardener separately in two measuring cups.
We calculated our mold volume by filling our 3D printed mold box with water and pouring the water into a measuring cup to find exact volume.
For two part molds like the one shown, you only need to mix enough silicone to fill half of the volume of your mold.
Once you have measured each part, combine the two parts into one mixing cup and stir slowly with a mixing tool.
Be cautious not to stir in air bubbles. Be sure to scrape the sides of the cup to mix in all material.
Once your parts are thoroughly mixed the curing process will begin.
TIP
Read instructions on your silicone for “pot-life”. This is how long you have to work with the silicone before it cures.
Supplies Used: Mixed silicone, prepared mold box and master
Pour silicone into the first half of your mold box.
When pouring, pour slowly into one corner of the mold box and allow the silicone to run to other parts of the mold box as it fills.
Stop when the silicone reaches the top of the first half of your mold box.
Once you have poured your silicone place small keys into the silicone. These will create negative spaces and allow the mold halves to fit together once poured. We will remove them before pouring the second half of our mold.
Depending on what type of silicone you are using it can take anywhere from 75 minutes to overnight to cure.
Temperature and humidity will affect curing times, so we recommend this process be done in a room temperature environment.
Step 10: Attach and Prepare Mold Part Two
Supplies Used: Mold box part two, hardware (nuts & bolts)
Once our mold has set, we will prepare to pour the second half of our mold.
A: Remove the keys you inserted in step 9.
B: Attach and secure second half of mold box.
C: Spray with mold release
Next, repeat steps 5-9 and create the second half of your mold using the methods mentioned above.
Step 12: Let Cure
Supplies Used: Pliers or Ex-Acto knife
Once both halves of your mold have cured you are ready to remove them from the mold box and begin using them to recreate parts.
A. Remove the hardware
B: Remove the mold from the mold box and open.
C: Remove the master and vents.
Supplies Used: Cured mold, mold release spray, rubber bands
Next, you will need to reassemble your mold.
A: Ensure that all parts of your mold are correctly aligned, and plug any holes created by vents.
B: Secure mold pieces using rubber bands, straps, or tape.
Tip
Another great application for 3D printing would be to design and print a box to hold the mold together when pouring resin, or modify the mold box we used to serve the same purpose.
TIP:
If your vents leave holes in areas where resin can spill out during the pour, they will need to be plugged.
Supplies Used: Resin (Part A & B), measuring cups, measuring sticks, dye.
Just as with silicone you will need to measure each part of the mixture taking into account the volume needed to create a part.
If you have made several molds, you can mix a larger quantity of resin and pour several molds at once.
Add dye to the part of the resin mixture specified in the instructions.
Step 16: Mix Resin
Combine both parts of the resin mixture and mix thoroughly being sure not to stir in air bubbles.
TIP:
Resins typically have a shorter “pot-life” than silicone meaning they will cure faster.
Step 17: Pour Resin
Supplies: Funnel
Once mixed, pour immediately into the opening of your mold using a funnel.
Pour slowly as not to overfill and spill resin.
Any resin that remains in the mixing cup will harden, but can typically be removed afterwards.
Step 18: Let Cure
Once poured, allow the resin to cure for the appropriate amount of time.
Supplies Used: Pliers
Once your resin has cured, you can open the mold and remove your cast part.
Any resin that escaped through seams or voids and cured is called “flash”. Flash will need to be removed from the part through post processing.
Below, you can see that we were able to recreate our perfume bottle cap in several different colors and opacities using silicone molding.
Visit one of our other applications pages for tips on how to take your print even further.
We recommend that you visit our pages on:
Silicone Molding Part II
Vacuum Forming
Sanding
Last but not least, remember to share your work with us on Thingiverse and social media @MakerBot.
We can’t wait to see what you make!
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All the secrets of casting in 3D printed molds.
Hi all!
A little more than a year ago, a 3D printer was purchased. Moreover, it was bought not as a toy, but with a very specific task - to print injection molds for polyurethane.
While the printer was driving, many acquaintances and other specialists argued and convinced that it was necessary to order milled aluminum molds, install a centrifuge for casting, and so on and so forth. But how can I order a milled mold for a lot of money, if a) it is not clear whether I made the configuration correctly b) even if everything is correct, how many thousands of years it will fight back, subject to an incomprehensible demand for my molded products ...
In general, the printer arrived, learned how to print and went into battle.
The main problem of casting molds is to model them correctly in order to:
1. It was convenient to print with the required quality.
2. Consider fluid movement and potential bubbles.
3. Easy mold separation and product removal.
4. Fast mold assembly and disassembly.
5. Mould-tight.
After a few kilos of damaged plastic, the search for the right shape is over.
So
- the injection channel must be made from top to bottom, thus the slurry goes from bottom to top, squeezing out air
- The channel must be quite wide. since I use a catheter syringe (160 ml can be bought at a pharmacy or on Ali), it makes sense to make a diameter of about 5-7 mm. The slurry is relatively thick and harder to push through a narrow channel.
- the entrance to the channel is made on a cone slightly larger than the cone on the syringe, because when connected, they are mutually compacted, as it were, and the slurry flows strictly along the channel.
- The form itself must not have sharp or protruding corners, as well as overhangs, under which and for which the bubble can catch.
- along the contour I make a tenon-groove connection. first, it positions the two halves. secondly, the groove is smeared with silicone sealant (retaining elasticity) and this gives an additional seal against the flow of slurry.
- it is also possible to provide holes in the mold for fastening parts and their centering.
Centering is very important! Even tenths of a millimeter will be reflected in the finished product as a not beautiful offset strip
Mountains are already written about the settings of the printing itself, the only thing is that I print forms mainly in ABS. Because, it is well and quickly smoothed out with acetone. By the way, finding real acetone is like finding real vodka. As a result, I guarantee the quality of the acetone of the pro shop, and the planet of the piece of iron. For the regions, auto paint shops are probably relevant. There is no acetone in construction markets and supermarkets such as obi and leroy, or it is called acetone, but plastic does not dissolve. I do all my production work outside of my home, so smells don't bother me. After dexterity with acetonite, you can achieve the result as in the photo and even much better.
Now let's move on to making the goo.
Before cooking, it is necessary to treat the molds with a wax separator, dry the wax (this is important), since not dried gives defects on the product in the form of flakes on the surface.
Assemble/fasten the form and prepare dishes, disposable gloves, scales and other accessories.
I have been using Silagerm fluids for a long time. They have different ones. Silicone and polyurethane and more. For my purposes, Silagerm 6030 is suitable. The designation of the last digit is the shore hardness. In general, 30kA after complete solidification resembles a very dense rubber and stretches well (and 90I will be like oak plastic). The manufacturer claims up to 600%, but in fact the thicker the less it stretches. 1-2 mm will stretch just 6 times.
Two-component slurry, mixed by weight. For this, ordinary kitchen scales were bought. The manufacturer recommends kneading and pouring for a long time and knead again. In my experience, if there is a mixer, then there is no point in stirring for longer than 1-2 minutes. During kneading, you can add dye. I have it in a syringe for less. I usually pour the dye by eye and 5-10 ml is enough for 300-500g of the main liquid, in fact, a teaspoon of the dye is enough for half a kilo.
something like this. When the liquid is mixed, the life goes on for minutes, depending on the density, it's different, but boobs should not be crushed. We quickly put the bucket in the vacuum.
What a vacuum chamber is for. While the slurry is stirred, many bubbles form in it. And even if you stir slowly and pichalno bubbles will still be. So it needs to be vacuumed. This will remove any bubbles and further stir the slurry.
Initially, the vacuum chamber was a glass jar, and everything interfered in it. When the volumes grew up, the question arose of increasing the volume of the chamber. The ideal option for price and durability was the Soviet pressure cooker. It is not so easy to find an unnecessary Soviet pressure cooker from friends and relatives! I had to buy a left-hander on the market for as much as 500r !!! ))
Unfortunately, there is no viewing window on it, but I already knew that the volume of the slurry increases several times during vacuuming, so the container is needed for mixing with a five-fold volume (300g - 1.
5l will just be). If the bubbles are not all removed (they can be seen, they pop up), you must quickly repeat the procedure.
Next, I draw in the liquid with a syringe (this makes it even more vacuumized) because direct pouring will again give ubiquitous bubbles, and I already press it into the mold. By the way, I forgot to write that the form should have exit channels and additional capacity at the top, since the material tends to spread and gradually settles down, respectively, the volume should be reserved for these processes. In either case, the sprues are trimmed, and the extra volume that comes out ensures that the mold is completely filled.
The form can be opened after two days. If everything went well. then the product will be free of defects, easily separated from the mold. The form itself can be immediately reused and until it becomes unusable.
Products according to the forms above:
By the way, the boot of the CV joint turned out to be so ribbed, because the form was printed with PLA and dichloroethane did not manage to smooth it out qualitatively.
Thank you all for reading! I tried to give out the maximum information that I have accumulated over the year. If you still have questions, ask, I will answer all.
3D printing mold making
Desktop 3D printing molding allows engineers and designers to get more functionality out of a 3D printer beyond prototyping. Molding opens up a world of production materials and provides the opportunity to produce small batches and sample test molds before using expensive
tools.
This booklet covers the following three mold making strategies: injection molding, high temperature molding and injection molded elastomers. Typically, molds are made from Formlabs clear resin, which is preferred for its transparency, although any standard resin can be used, and high temperature resin is ideal for processes with high temperature requirements. It should be noted that these processes are best suited for stereolithographic 3D printing (SLA) because the printed parts are isotropic and waterproof.
Prototyping and small-scale production with 3D printing tools
| Process | Equipment | Run time | Material cost (for example: 300 ml / cm3) |
| Do-it-yourself mold making and parts making | Mold 2 and injection molding machine | 5 to 24 hours (form print time) | Approximately $50 for High Temperature Resin |
| Outsourced SLA Form | injection molding machine | 3-5 days | Approximately $700 for back office printing on industrial SLAs |
| Outsourced metal mold | injection molding machine | 1-2 weeks | Approximately $6,400 for office desk, aluminum finish |
| Outsourced mold Creation and production | no - full outsourcing | 1-3 weeks | $4,000 to $15,000 depending on volume and materials |
Silicone molding and some desktop molds are available using Formlabs Standard Resins High Temp, which has the highest HDT at 0.
45 MPa for any 3D printed materials currently on the market and allows print parts that can be used for high temperature forming such as thermoforming and injection molding of materials with higher melt temperatures
Injection molding
Form 2 high resolution SLA 3D printing can be used for rapid prototyping of inexpensive injection molds that can be used to make real parts from a wide variety of
thermoplastic materials. Injection molds can be used to test mold designs prior to making metal tooling or to produce low-volume parts
3D Printed Injection Molding covers injection molding using Formlabs clear resin printed molds. Following the release of Formlabs High Temperature Resin, designed to achieve higher heat resistance and stiffness, the booklet has been updated to describe the benefits of High Temperature Resin plates that are less likely to break due to thermal shock or temperature-related deformation
USB Device Enclosure Mold, 3D Printed on Form 2 High Temperature Resin
This mold contains a core, a cavity and two "gates" leading to the two halves of the enclosure.
High temperature resin molds can be used to mold a wide range of thermoplastics without thermal stress or temperature-related deformation
Formlabs High Temperature Resin can be used to injection mold a wide range of plastics.
3D printed mold tools reproduce the exact quality of the SLA print finish on the Form 2. Forms can be printed at 100 microns for faster prototyping or the recommended 50 microns for fine detail and smoothness
electronics molded in HDPE with a High Temp tool.
This shape of the USB case has been adjusted over three iterations to remove pits, entrapped air, and partial shrinkage. Total cost of materials for prototyping this high temperature resin mold tool: $25
Thermoforms
Form 2 3D printed thermoformed dies are a fast and efficient way to create high quality vacuum formed parts for low volume production. Printed thermoformed dies can be used to make packaging prototypes, clean orthodontic retainers, and food-safe molds for chocolate confectionery.
Thermoforming dies experience less pressure than injection molds, but still reach high surface temperatures.
High temperature polymer resists deformation and surface degradation from the combined heat and pressure of thermoforming for most plastics. Standard resins may also be suitable for thermoforming with some low temperature plastics such as vinyl.
APPLICATION EXAMPLE
Formech thermoformed prototype packaging.
Thermoforming a thin sheet of polycarbonate over a high temperature polymer matrix produces a transparent piece by matching the geometry and detail of the matrix. Thermoformed packaging can be easily prototyped and incorporated into the design process along with 3D printed product prototypes, and all this is achievable on the Form 2. The printed matrix was used without additional processing and the need for UV curing. Texture is recommended in thermoforming design to prevent air trapping under the sheet - layer lines on the printed thermoforming die can be helpful in this regard.
TEMPERATURE CONTROL
High Temperature Polymer Cycle Thermoforming
The surface temperature of the die reaches 130°C. The high temperature resin is highly resistant to deflection, whereas with standard resins you must allow the print matrix to cool between cycles, otherwise warping and degradation may occur.
If temperature rise becomes a limiting factor in molding efficiency, cooling channels are an effective way to remove heat from the print. When used in conjunction with an automated thermoforming machine, the water-cooled die can produce more parts with shorter cycle times.
Conformal water channels visible in the high temperature thermoforming die.
Thermoforming die surface temperature
Conformal cooling channels are easy to implement when designing for SLA 3D printing and print successfully without any internal supports to interfere with flow. After printing, the channels are flushed with uncured resin using isopropyl alcohol.
The mold is connected to a pump and a source of cold water.
Integrated water cooling as a strategy can also be applied to standard and rigid polymer parts to reduce heat dissipation when used in higher temperature environments.
Elastomer casting
Precision molds for most flexible elastomers such as silicone and urethane rubber can be printed on the Form 2 using standard resin. The transparency of Clear Resin allows the material to be observed during the pouring or injection process. Flexible materials can be easily removed from rigid SLA printing plates, and applications from model production to functional molding can be obtained. Silicone molding can also be used to quickly replicate master prints, greatly reducing production time when multiple rigid parts and objects are needed.
APPLICATION EXAMPLE
Forms printed on Form 2 are used to create composite parts with advanced built-in features. Assembly subcomponents such as electronic, metal and SLA printed elements can be embedded and sealed in soft surface molds.
RightHand Robotics used the Form 2 to create the production blocks of their robotic gripper using urethane molding. The forms were printed in clear resin, with black resin inserts forming the internal structure.
The Form 2 printer allowed RightHand Robotics to move from prototypes to small-scale production without the need for expensive tooling. The rapid transition from original printed prototypes to production materials that have longer flex cycle life was done with 3D printed plates on the same Form 2 hardware they used for initial prototyping.
The first layer applied from RightHand Robotics' multi-stage process includes urethane compounds that can withstand multiple flex cycles while still providing the high elasticity needed to securely return the gripper to its open state.
The outer layer provides improved tactile grip and control, as well as sealing the sensor electronics with softer, lower durometer rubber.
SLA 3D printed parts can also be encapsulated inside molds to provide a rigid structure for flexible materials.
