3D printed iris diaphragm

Accuracy may also vary depending on the media you are printing on and the mechanical properties of those media, which can also affect the likelihood of model warping.

Formlabs Rigid Resin has a high "green modulus", or modulus of elasticity before final polymerization, which allows you to print very thin models with high definition and reliability.

But, again, it all depends on your goals. For example, in dentistry, the accuracy of 3D printed models is critical. But if you're printing a concept model, chances are you just want to get a general idea of ​​the physical product, and accuracy won't be that important. nine0003

Margins, mold surfaces, and contact surfaces printed with Formlabs Model Resin are accurate to within ±35 µm of the digital model at over 80% of surface points when printed at 25 µm settings. The overall accuracy across the entire arc is within ±100 µm on 80% of surfaces when printed with settings of 25 or 50 µm.

3D printed models often need to be cured, which in turn often leads to shrinkage. This is normal for any part made using SLA or DLP 3D printing. Depending on the printer, this phenomenon may need to be considered in the design. PreForm, Formlabs' free file preparation software, automatically compensates for this shrinkage, ensuring that the final cured models are the same dimensions as the original CAD model. nine0003

How does the final polymerization work? Learn more about the theory behind the process and see efficient ways to successfully finish curing models made with stereolithographic 3D printers.

Producing quality models on a 3D printer requires attention not only to the printer itself, but to the entire production process.

The final result may be affected by the print preparation software, post-processing materials and tools used. In general, integrated systems designed to work together produce more reliable results. nine0003

Unlike machining, where parts are progressively improved to tighter tolerances, 3D printing has only one automated manufacturing step. While complex coating adds cost to processes such as CNC milling, creating complex features with 3D printing is essentially free, although the tolerances of a 3D printed model cannot be automatically improved beyond the capabilities of the printer. without resorting to subtractive methods. nine0003

3D printing is a great option if you have rough, complex features such as undercuts and complex surfaces, and don't necessarily need surface accuracy better than ±0.125mm (standard machining). Tolerances beyond standard machining must be achieved using subtractive methods, either through manual or machine processing, for both 3D printed and CNC models. nine0003

SLA has the highest tolerance compared to other commercial 3D printing technologies. The tolerances for stereolithographic 3D printing are somewhere between standard and precision machining.

In general, more malleable stereolithography materials will have a wider tolerance zone than more rigid materials. Designing subassembly parts for tolerance and fit reduces post-processing time and simplifies assembly, as well as reduces material costs per iteration. nine0003

There are many other factors to consider when evaluating 3D printers. Should your models be isotropic? What mechanical properties should your models (and, accordingly, the materials from which they are made) have? The best place to start is to get familiar with the physical models printed on a 3D printer. Order a free material sample from Formlabs of your choice and see for yourself the quality of your stereolithography print.

Request a sample 3D model

Post-processing of 3D printed parts (PLA, ABS, SBS, PETG)

Table of Contents

• Remove Supports
• Removing Soluble Supports
• Sanding
• Cold welding
• Filling voids
• Polishing
• Priming and painting
• Steam smoothing
• Epoxy coating
• Metallization

Introduction

FDM technology is best suited for rapid, low-budget prototyping. Layer lines are usually visible in FDM prints, so post-processing is essential if a smooth surface is to be achieved. Some post-processing techniques can also make a print more durable by changing the degree of its elastic properties, density, structural and textural features.

In this article, we will discuss the most common post-processing techniques in FDM. nine0003

Post-processed FDM prints (left to right): cold welded, void filled, raw, sanded, polished, painted and epoxy coated. Photo 3dhubs.com

Removing Supports

Removing supports is usually the first step in post-processing for any 3D printing technology that uses them. In general, props can be divided into two categories: standard and soluble. Unlike other post-processing methods discussed in this article, the removal of props is mandatory and does not result in improved surface quality. nine0003

Initial printout with props, poor prop removal, good prop removal. photo 3dhubs.com

Removal of standard props

Tools

• Wire cutters, needle nose pliers, tongs
• Toothbrush, brush

Process

Normally the backups come off the printout without problems, and hard to reach places (such as holes or cavities) can be cleaned of the backup material with an old toothbrush. Proper placement of support structures and correct print orientation can significantly reduce the negative impact of supports on how the final printout will look. nine0003

Pluses

• Does not change the overall geometry of the part.
• The process is very fast.

Cons

• Does not remove layer lines, scratches or other surface defects.
• If excess material or marks remain from the support structure, print accuracy and appearance suffer.

Soluble Support Removal

Instrumentation

• Solvent resistant container
• Thinner
• Ultrasonic cleaner (optional)

Process

Soluble support standard materials are removed from the printout by immersing it in a reservoir of the appropriate solvent. Supports are usually printed:

• HIPS (usually with ABS)
• PVA (usually with PLA)

A glass container like a preservation jar is fine. Any non-porous vessel is suitable for water treatment. To quickly remove props from HIPS/ABS printouts, you will need a solution of equal parts D-limonene and isopropyl alcohol. Many other support structure materials such as PVA (with PLA) dissolve in normal water.

Pro Tricks

Shorten the solution time by using an ultrasonic cleaner and changing the solvent as it becomes saturated. A warm (not hot) solution works faster - heating is useful if there is no cleaner. nine0003

Pluses

• Complex geometry is allowed for which the standard method of removing props is not possible.
• Smooth surface at the support points.

Cons

• Improper dissolution of the supports can cause discoloration and skewed printouts.
• Does not remove layer lines, scratches or other surface imperfections.
• May cause small holes or holes if soluble material seeps into the object during printing. nine0130

Scrap with a skin

SHIP SHIC ABS ABS ABS PROBECTION

Instrumentation

• FORESTIONAL PREASE with grain
  on 150, 220, 400, 600, 1000 and 200
9013ANDS
• Cleaning cloth
• Toothbrush
• Soap
• Face mask

Process

Once the props have been removed or dissolved, sanding can be done to smooth the part and remove any obvious defects such as blots or prop marks. Which sandpaper to start with depends on the thickness of the layer and the quality of the print: for layers of 200 microns or less, or for prints without blotches, you can start with sandpaper at P150. If there are blobs visible to the naked eye, or the object is printed with a layer thickness of 300 microns or more, stripping should begin with P100. nine0003

The process can be continued up to P2000 grit (one approach is to go to 220, then 400, 600, 1000 and finally 2000). Wet sanding is recommended from the very beginning to the very end - this will avoid excessive friction, which can lead to an increase in temperature and damage the object, as well as contaminate the sandpaper itself. Between sanding, the printout should be cleaned with a toothbrush and washed with soapy water, then wiped with a cloth to remove dust and prevent it from sticking together. Even P5000 can be sanded to achieve a smooth, shiny FDM part. nine0003

Pro Tricks

Always sand in small circular motions - evenly over the entire surface of the part. It may be tempting to sand perpendicular to the layers, or even parallel, but this can lead to gouges. If the part is discolored or has a lot of scratches after sanding, it can be heated a little to soften the surface and allow some defects to smooth out.

Pros

• An exceptionally smooth surface is obtained.
• Further post-processing (painting, polishing, smoothing and epoxy coating) is greatly facilitated.

Cons

• Not recommended for double or single shell parts as sanding may damage the printout.
• The process is difficult in the case of sophisticated surfaces and the presence of small details in the object.
• Grinding too aggressively and removing too much material can affect the appearance of the part. nine0130 Acetone for ABS. Dichloromethane for PLA, ABS
• Foam applicator

Process

If the size of the object exceeds the capacity of the printer, the object is printed in parts and then assembled. In the case of PLA and some other materials, assembly can be done with Dichloromethane or a suitable adhesive (the choice of adhesive depends on the plastic). In the case of ABS, it is possible to "weld" with acetone. The mating surfaces should be slightly moistened with acetone and squeezed tightly or clamped and held until most of the acetone has evaporated. So the parts will be held together by chemical bonds. nine0003

Pro Tricks

Increasing the surface area of ​​the acetone contact increases bond strength. Tongue-and-groove to help.

Pros

• Acetone does not change surface color as much as most adhesives.
• After drying, the compound acquires the properties of ABS, which makes further processing easier and more uniform.

Cons

• The bonding of ABS parts by cold acetone "welding" is not as strong as if the part were printed as a whole.
• Excessive use of acetone can dissolve the part and affect final appearance and tolerances.

Void Filler

Black ABS Print, Filled and Sanded

Tool Kit

• Epoxy (for small voids only)
• Automotive body filler (large voids and joints)
• ABS filament and acetone (only for small voids in ABS printouts)

Process

Unusual voids may come out after the part has been ground or the soluble props have been dissolved. These voids are formed during printing when the layers are incomplete due to any restrictions on the trajectory of the print head, which is often inevitable. Small gaps and voids can be easily filled with epoxy and no additional treatment is required in this case. Larger gaps or voids left by assembling a multi-part object can be filled with automotive bodywork filler, but the printout will then need to be re-sanded. Putty works great, is easy to process with sandpaper and can be painted. Moreover, the parts connected by such a filler, or voids filled with it, turn out to be stronger than the original plastic. nine0003

Slots in ABS printouts can also be filled with ABS thinned with acetone, which reacts chemically with the ABS object and seeps into existing voids. It is recommended to make such a putty from 1 part ABS and 2 parts acetone, then it will not spoil the surface if used correctly.

Dichloromethane works on all plastics: ABS, PLA, HIPS, SBS, etc.

Epoxy is also useful if you want to make your 3D printed part more durable

Pros

• Epoxy filler is easy to sand and prime, resulting in an excellent surface for painting.
• ABS solution of the same filament will give the same color so nothing will be visible on the surface.

Cons

• Auto body filler or other polyester epoxy adhesive is opaque when dry and will leave discolored areas on the printout. nine0130
• Additional processing required to achieve a uniform surface.
• Grinding too aggressively and removing too much material can affect the appearance of the part.

Polished

PLA model, polished. Photo rigid.ink

Tools

• Plastic polishing compound
• Sandpaper for P2000
• Cleaning cloth
• Toothbrush
• Polishing pad or microfiber cloth

Process

Once the part has been cleaned, a plastic polish can be applied to the part to give a standard ABS or PLA object a mirror finish. After the part has been sanded for 2000, it is necessary to remove dust from the printout with a cloth and rinse the printout under warm water using a toothbrush. When the object is completely dry, buff it on a buffing pad or microfiber cloth, adding a polishing compound as you go, such as polishing jewelry. They are designed specifically for plastics and synthetics and give a long-lasting shine. Other plastic polishes, such as those used to polish car headlights, also work well, but some of them contain chemicals that can damage the printout. nine0003

Pro Tricks

To polish small parts, place the polishing wheel on your Dremel (or other rotary tool such as a power drill). For larger and stronger parts, you can use a grinder, just make sure that the part does not stay in one place for too long, otherwise the plastic may melt from friction.

Pros

• The part is polished without solvents that can warp it or change its tolerances. nine0130
• When properly ground and polished, a mirror-smooth surface is obtained, very similar to cast.
• Polishing and deburring plastics is extremely economical, making this a very cost-effective method of achieving a quality finish.

Cons

• If you want to achieve a mirror-smooth surface, the part must be carefully ground before polishing, which may affect tolerances.
• After polishing, the primer or paint no longer sticks.

Primer and paint

Gray PLA FDM print spray painted black. 3dhubs.com

Tools

• Cleaning cloth
• Toothbrush
• 150, 220, 400 and 600 grit sandpaper
• Aerosol Primer for Plastics
• Finish paint
• Polishing sticks
• Polishing paper
• Masking tape (only if multiple colors are expected)
• Nitrile gloves and matching face mask

Process

After the printout has been properly sanded (it is enough to reach P600 when painting), it can be primed. Aerosol plastic primer should be applied in two coats. This primer is intended for subsequent painting of models, provides an even coating and at the same time thin enough not to hide small elements. Thick primer, which is sold in hardware stores, can clump, and then you have to seriously work with sandpaper. Apply the first spray coat with short pressures from a distance of 15-20 cm from the object, trying to do it evenly. Let the primer dry and smooth out the unevenness with 600 grit sandpaper. Apply a second coat of spray with light, quick pressures, also very gently and evenly. nine0003

When the priming is completed, you can start painting. You can paint with artistic acrylic paints and brushes, but a spray gun will provide a smoother surface. Hardware store spray paints are thick and viscous and difficult to control, so use paints that are designed specifically for modeling. The primed surface must be sanded and polished (sanding and polishing sticks, which are used in nail salons, can be purchased online, they are great for our task), and then wiped with a cloth. The paint should be applied to the model in very thin layers, the first layers should be transparent. When the paint finish becomes opaque (usually 2-4 coats), let the model rest for 30 minutes to allow the paint to dry completely. Carefully polish the paint layer with manicure sticks, repeat the procedure for each of the colors (between each applied paint). nine0003

Separate parts of the model can be covered with masking tape so that the colors, if there are several, do not mix. When painting is complete, remove the masking tape and polish the object with polishing paper. Polishing paper, such as 3M or Zona, comes in a variety of grits and is a relatively new product. It is sold in packs in various online stores, and after processing with this paper, the ink layer or topcoat will literally shine - and nothing else can achieve this effect. Apply 1-2 coats of top coat to protect the paint and let it dry completely. The top coat is selected in accordance with the recommendations of the paint manufacturer. If the topcoat and paint are incompatible, it can render your entire painting job meaningless, so compatibility is very important here. nine0003

Pro Tips

Don't shake the can when spraying! It is important not to mix the pigment or primer with the propellant (propellant gas), which will cause bubbles to form in the spray. Instead, the can must be rotated for 2-3 minutes so that the mixing ball rolls like a pearl, and does not strum.

Pros

• Excellent result, if you take into account all the nuances of the process and practice.
nine0129 You can do anything with the final look of the object, no matter what material it is printed on.

Cons

• Primer and paint increase the volume of the model, which affects tolerances and can be a problem when it comes to a part of a larger object.
• A high quality spray paint or spray gun increases costs.

Vapor smoothed

Vapor smoothed black ABS printed hemisphere

Tools

• Cleaning cloth
• Solvent resistant sealed container
• Thinner
• Paper towels
• Aluminum foil (or other solvent resistant material)
• Face mask and chemical resistant gloves

Process

Line the bottom of the container with paper towels, if possible along the sides. It is critical that the vapors cannot damage the container and that the container itself is sealed. It is recommended to use a glass or metal container. Apply enough thinner to the paper towels so that they are wet but not soaked - this will also help them adhere better to the walls. Acetone is famous for its ability to smooth out ABS. PLA can be smoothed with a variety of other solvents (dichloromethane works well), but this plastic tends to be much harder to smooth than ABS. When working with any solvents, please follow the safety precautions for handling chemicals and always take appropriate precautions. Place a small "raft" of aluminum foil or other solvent-resistant material in the center of the paper towel-lined container. Place the printout on the "raft" (either side of your choice) and close the lid of the container. Steam polishing can take varying amounts of time, so check your printout periodically. To increase the speed of polishing, the container can be heated, but this must be done carefully so as not to cause an explosion. nine0003

When removing the printout from the container, try not to touch it in any way, leave it on the “raft”, take them out together. In all those places where the printout has come into contact with something, there will be defects, since the outer layer will be under-dissolved. Before working with it, let the printout completely “breathe” so that all solvent vapors have evaporated.

Many aerosols and/or solvent sprays are flammable or explosive and their vapors can be harmful to humans. Be extremely careful when heating solvents, always handle them and store them in a well ventilated area. nine0006

A galvanizing solution can be obtained by mixing a metal salt, acid and water, but if the proportions are inaccurate and the substances are of insufficient quality, one cannot count on a professional result. If you buy a ready-made solution (as in Midas kits), you can be sure that the problems with plating are not caused by the solution. nine0130
• Sacrificial anode. The anode material must match the metal of the solution: for example, if copper sulfate is used in the solution (with water it is copper sulfate), then the anode must also be copper. Any object made of the appropriate metal will do (for example, copper wire for copper plating), or you can buy special strips of metal for galvanization.
• Conductive paint or acetone with graphite. Electroplating requires the surface of the printout to be electrically conductive, and this can be achieved with a conductive paint or a solution of equal parts graphite and acetone. Conductive paint will work with any material, but acetone with graphite will only work with ABS. nine0130
• Power rectifier. A simple battery can be used as this element, only it will not be as efficient and will not give a fast enough result than the rectifier itself (household current). The rectifier is safer in the sense that it can simply be turned off and thus cut off the current during the galvanization process.
• Conductive screw or eye hook
• Non-conductive container
• Contacts
nine0129 Non-conductive gloves and goggles. Electroplating solutions are acidic and can cause injury if splashed into the eyes, so wearing goggles is very important. Solutions also irritate the skin and conduct electricity, so insulating gloves are needed.

Finishing	★ ★ ★ ★ ☆
Approvals nine0190	★ ★ ★ ☆ ☆
Speed ​​	★ ★ ★ ★ ☆
Suitable for	all thermoplastics FDM

Process

Electroplating can be carried out at home or in a professional workshop. To do everything right, you need to be well versed in the materials, in what is actually happening - and at home these opportunities are usually limited. In order to achieve excellent surface quality and to have more plating options, including chrome plating, it is best to use the services of professional workshops. The copper galvanization process will be described below as an example. nine0003

At home, you can galvanize with copper or nickel, and this coating will then serve as the basis for galvanizing with other metals. It is critically important that the printout surface be as smooth as possible before it is galvanized. Any bumps and lines in the layers will be enhanced as a result of the process. Prepare the sanded and cleaned object for plating by coating the plastic with a thin coat of high quality conductive paint, or with a graphite and acetone solution for ABS printouts. Allow the conductive coating to dry completely, sand if necessary to ensure a smooth surface. At this stage, it is extremely important not to touch the printout with bare hands or to wear gloves, because sweat marks on the object will certainly affect the quality of the galvanization. nine0003

Insert a screw or eyelet in an inconspicuous place on the printout and connect it to the negative terminal of the rectifier. This will be the cathode. Connect the copper anode to the positive contact of the rectifier. Fill the container with enough copper plating solution so that the printout is completely covered with it. Immerse the anode in the container and turn on the power. After the rectifier is turned on, immerse the printout in the container, making sure that it does not touch the anode anywhere. nine0005 Beware! When the object is already in the bath, the galvanization system is active, and contact with the solution, cathode or anode can be traumatic. Set the voltage on the rectifier to 1-3 Volts, and the process will go to full metallization. To speed things up, the voltage can be increased, but not more than 5 volts. When enough metal has deposited on the printout, simply turn off the power and dry the object with microfiber towels. When it's dry, varnish the object to protect it from corrosion.

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