Filament Usage Guide

For users new to 3D printing, establishing good habits for handling and storing filament is essential for reliable print results.

This guide walks through the typical workflow—from opening a new spool, drying the filament, loading it into the printer, to proper storage after printing.

Tip: If you are new to FDM printing, PLA is usually the best material to start with. It is easy to print, requires minimal tuning, and generally provides a higher success rate compared to many engineering materials.

(1) Opening the Filament Package

When receiving a new spool of filament, first inspect the vacuum packaging carefully.

Check whether:

●the bag remains tightly vacuum-sealed

●the sealing edge is intact

●the desiccant packet shows any color change

These indicators help determine whether the filament may have been exposed to moisture during transportation or storage.

Recommended unpacking steps

●Use scissors to cut along the sealed edge of the bag

●Avoid damaging the filament, sealing strip, or desiccant pack

●Keep the desiccant and filament clip for later storage use

Even if the packaging appears intact, filament may still absorb small amounts of moisture after long shipping periods or storage in humid environments. For best results, drying the filament before printing is recommended.

(2) Drying the Filament

Drying filament before printing helps ensure consistent print quality, especially if the vacuum packaging appears loose. When filament absorbs moisture, it may produce bubbling or popping during extrusion, increased stringing, reduced layer adhesion, and in some cases nozzle clogging.

Pre-drying is one of the most effective ways to avoid these issues. Drying conditions vary depending on the material; for example, PLA is typically dried at around 50 °C for 4–6 hours. Regularly checking and drying filament helps maintain stable printing performance and prevents unnecessary print failures.

(3) Loading the Filament

SUNLU is committed to developing efficient and sustainable 3D printing solutions. Our third-generation reusable spool system improves on traditional spool designs while providing a more convenient and environmentally conscious printing experience.

To support different user needs, SUNLU filaments are available in two formats: standard filament spool and filament refill (spool-less).

If you already own several SUNLU reusable spools, refill filament can be a practical option for future purchases. It reduces storage space requirements, minimizes packaging waste, and helps lower long-term material costs.

(If you are not using refill filament, you may skip the following installation steps.)

Installing Refill Filament

1.Remove the refill filament and the nylon zip tie from the packaging box. Do not remove the tie yet, as it prevents the filament from unraveling.

2.Before removing the previous filament from your spool, use the included zip tie to secure the remaining coil through the center of the spool. This helps prevent tangling during removal.

3.Hold the spool firmly and rotate it counter-clockwise to remove the remaining filament.

4.Install the new refill filament onto the spool, align the markings, and rotate the spool clockwise until it locks into place. You should hear a “click,” indicating that the locking mechanism is engaged.

5.Carefully remove the zip tie and keep it for future spool changes.

After drying, place the filament on the printer’s spool holder or AMS system. Feed the filament into the PTFE tube and select the “Load Filament” option on the printer’s control panel.

When inserting the filament, apply steady pressure. Some printers—especially new ones—may require slightly more force. If insertion is difficult, cut the filament tip at a 45° angle, then insert it straight into the extruder inlet. Once the filament begins feeding into the extruder, continue holding it in place for about 10 seconds to ensure proper loading.

(4)Start Printing

1.Prepare the model and slicing settings: Load or design your 3D model on your computer. Use slicing software such as Bambu Studio or Cura to select the correct material profile and configure the recommended printing parameters.

2.Send the print job: Transfer the sliced file to the printer. Confirm the settings on the printer interface or within the slicing software, then start the print.

3.Printing and post-processing: The printer will automatically execute the print job. After the print is complete, perform the necessary post-processing steps depending on the material. These may include removing the model from the build plate, removing supports, and cleaning or curing the part if required.

(5) Storing Filament

Proper filament storage helps maintain consistent print quality and extends the usable life of the material. If the filament will not be used for an extended period after printing, follow these steps:

1.Unload the filament

Use the printer’s unload function to retract the filament from the extruder and hotend.

2.Secure the filament end.

Remove the spool from the spool holder and insert the loose filament end into the spool clip or the side hole on the spool to prevent it from loosening and tangling.

3.Seal against moisture

Place the spool in a sealed bag or a dry box to protect it from moisture. For hygroscopic materials such as PLA, PETG, and Nylon, adding desiccant packs is strongly recommended.

4.Store in a proper environment

Keep the sealed filament in a cool, dry place away from direct sunlight. Proper storage conditions help maintain stable material performance and reduce printing issues caused by moisture absorption.

Once you become comfortable with basic printing and start exploring how to achieve stronger parts, finer details, or faster print speeds, you have moved into the advanced stage of FDM printing. At this point, the focus shifts from simply completing prints to improving overall print quality and expanding application possibilities.

This guide introduces several key areas that help experienced users further refine their workflow:

●Material Selection and Expansion: Gain a deeper understanding of different filament properties and learn how to select the right material for specific projects, allowing you to move from basic usability to optimized performance.

●Advanced Printer Tuning: By adjusting printing parameters and machine settings, users can push their printers closer to their performance limits and achieve higher levels of precision and stability.

●Application Expansion: Topics include hardware upgrades, multi-material printing optimization, and advanced post-processing methods that help extend the practical applications of desktop 3D printing.Follow the sections below to progressively refine your printing workflow and build a more reliable and efficient printing setup.

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Follow the sections below to progressively refine your printing workflow and build a more reliable and efficient printing setup.

(1) Material Selection and Expansion

When working with specific design requirements, the following reference table can help quickly narrow down two or three suitable material options. It highlights key technical considerations and basic requirements for each material, allowing you to select the right filament and start your project more efficiently.

Definition – Mechanical Properties:

Mechanical properties describe how a printed part behaves under physical loads and stresses in practical use. They include characteristics such as strength, toughness, hardness, impact resistance, and fatigue resistance.

The sheet above provides a fast material-selection pathway based on specific application needs. However, to truly master material usage, it is necessary to develop a systematic understanding of the characteristics of different types of 3D printing materials.

Currently, in the 3D printing materials range are mainly included: polymer materials, metal materials, ceramic materials, and composite materials. Among these, polymer materials—which can be further divided into engineering plastics and bioplastics—dominate both consumer-level and industrial-level applications due to their lower cost and high printability.

PLA (Polylactic Acid)

PLA is a bio-based biodegradable plastic made from plant-derived materials such as corn starch and sugarcane. You can think of it as “plastic made from plants.” Because of this property, PLA is widely regarded as one of the most environmentally friendly and beginner-friendly materials in 3D printing.

Why Do Beginners Usually Start with PLA?

1. Easy to print and beginner-friendly

PLA is widely known as one of the easiest 3D printing materials to work with. Typical nozzle temperatures range from 180–220 °C, and the heated bed can often be set to 50–60 °C or even left unheated.

2.Minimal warping

PLA has a very low shrinkage rate during cooling, which significantly reduces the risk of warping. Even larger prints tend to maintain good dimensional stability, making PLA ideal for beginners.

3. Low odor during printing

Unlike many other plastics, PLA produces very little noticeable odor while printing, making it suitable for use in homes, classrooms, or offices.

4.Good surface finish

PLA generally produces smooth surfaces and clean layer definition, resulting in visually appealing prints without extensive post-processing.

5.Wide variety of colors and effects

PLA filaments are available in a broad range of options, including standard colors, silk finishes, gradients, metallic effects, wood-filled filaments, glow-in-the-dark variants, and more, offering great creative flexibility.

6.More environmentally friendly

Because PLA is derived from renewable plant resources, it is often considered one of the more environmentally friendly plastics used in 3D printing, and it can biodegrade under industrial composting conditions.

Limitations

1.Limited mechanical strength

PLA is relatively brittle compared to engineering plastics, which means it can crack or break under heavy loads or repeated bending. It is therefore less suitable for functional parts that must withstand significant mechanical stress.

2.Low heat resistance

PLA begins to soften at around 60 °C, so printed parts may deform when exposed to heat—for example inside a car on a hot day or near heat sources.

3.Poor long-term outdoor durability

Extended exposure to sunlight, heat, and moisture can gradually weaken PLA, causing it to become brittle over time.

How to Print with PLA

Nozzle temperature: Start at 200 °C and fine-tune according to print quality.

Bed temperature: 50–60 °C

Print speed: 50–60 mm/s

Cooling fan: Must be enabled.

PLA Variants

In addition to standard PLA, you will often encounter various PLA-based filament variants:

PLA+: An improved version of PLA with enhanced toughness and strength, while maintaining similar ease of printing. A great upgrade option for beginners.

Silk PLA: Produces prints with a silky, metallic-like glossy finish, ideal for decorative models.

Wood PLA: Contains wood powder, allowing prints to be sanded, stained, or painted to achieve a realistic wood texture.

Dissolvable Support PLA: Used in dual-extruder printers as support material. After printing, it can be dissolved in a specific solution, enabling extremely complex geometries.

Galaxy PLA: Creates prints with a sparkling, star-like effect, resembling a deep galaxy under direct light, which is perfect for space-themed or fantasy models.

Rainbow PLA: Features shifting color gradients within one filament, allowing a single print to display smooth multicolor transitions without having to switch spools during the printing process.

Glow-in-the-Dark PLA: Contains phosphorescent additives that absorb light and emit a glow in darkness. Suitable for warning signs, decorative lamps, and fantasy-themed models.

Matte PLA: Produces prints with a premium matte finish, which helps hide layer lines and reduce reflections.

PETG (Polyethylene Terephthalate Glycol)

PETG is a clear thermoplastic polyester known for its good transparency, toughness, chemical resistance, and resistance to stress whitening. It is commonly used in industrial manufacturing processes such as thermoforming and extrusion blow molding.

In 3D printing, PETG offers an excellent balance between printability and mechanical performance. Compared with PLA, it provides greater durability while remaining relatively easy to print, making it a popular next-step material for users moving beyond PLA.

Key Advantages

1.Higher strength and toughness

PETG is significantly more impact-resistant and flexible than PLA, making it less prone to cracking or breaking. This makes it suitable for functional parts such as clips, brackets, and tool handles, where durability is important.

2.Strong layer adhesion

PETG forms very strong bonds between layers, resulting in prints with relatively low anisotropy and improved overall structural strength.

3.Easy to print with minimal warping

Although PETG requires slightly higher temperatures than PLA, it still has low shrinkage during cooling, meaning warping is rarely a problem. It generally prints reliably without requiring a strictly controlled environment.

4.Good chemical and physical resistance

PETG offers good resistance to oils, grease, and common cleaning agents. It can also produce attractive semi-transparent parts, which makes it useful for aesthetic or functional applications.

Limitations

1.Surface scratches more easily

PETG is somewhat softer than PLA, so printed parts can be more prone to scratches during handling or post-processing.

2.Stringing during printing

PETG tends to produce fine strings of filament between printed areas, especially if retraction settings and temperature are not properly tuned.

3.Cooling must be carefully balanced

Adequate cooling is important for small features and overhangs, but excessive cooling can weaken layer adhesion. Achieving the right balance is key to good results.

How to Print PETG

Nozzle temperature: 220–250 °C (starting around 230 °C is recommended)

Bed temperature: 70–80 °C

Print speed: Around 40–60 mm/s

Cooling fan: Use 30–50% fan speed.

Too little cooling may increase stringing, while too much cooling can weaken layer bonding.

Important tip: Avoid letting the nozzle drag across previously printed layers. Enabling Z-hop during travel moves can help prevent the nozzle from catching on the print and potentially dislodging the part when printing PETG.

PCL (Polycaprolactone)

PCL is a low-temperature thermoplastic biodegradable polymer. Its most distinctive feature is its very low melting point—around 60 °C. Like many bio-based materials, PCL is widely used in specialized applications, particularly in the biomedical field, such as drug delivery systems and surgical sutures.

PCL also exhibits shape-memory properties, meaning it can be reheated and reshaped after printing. Because of its extremely low melting temperature, PCL requires much lower printing temperatures than most thermoplastics, which can also reduce energy consumption during printing.

In medical research and biomedical engineering, PCL has been explored for applications such as 3D-printed scaffolds and cardiovascular implants, including experimental heart stents.

1. Very low printing temperature

PCL melts at around 60 °C, allowing it to be printed at much lower temperatures than most thermoplastics. Typical nozzle temperatures range from 70–90 °C, and a heated bed is generally unnecessary since the material adheres well at room temperature.

2.Flexible and elastic

Printed PCL parts remain soft and flexible at room temperature, with properties similar to rigid rubber. They can be bent or compressed without cracking.

3.Shape-memory capability

When reheated above about 60 °C, PCL softens again and can be reshaped. After cooling, it retains the new form, allowing printed parts to be adjusted, repaired, or even "welded".

4.Biodegradable and biocompatible

Under suitable environmental conditions such as soil or compost, it can break down into harmless substances over time.

Limitations

1.Low mechanical strength and heat resistance

PCL has much lower mechanical strength than materials such as PLA, and it softens quickly at temperatures above 60 °C, which limits its use in load-bearing or high-temperature environments.

2.Limited storage stability

After opening, PCL filament should be stored in sealed, moisture-controlled conditions. Prolonged exposure to humidity may cause the material to degrade or become brittle.

3.Surface stickiness in warm conditions

In warmer environments, printed PCL parts may feel slightly tacky, so applying a protective surface coating can help improve durability.

How to Print PCL

Nozzle temperature: 70–90 °C (avoid exceeding 100 °C)

Bed temperature: Off or room temperature

Print speed: 30–50 mm/s

Cooling: Using strong part cooling can help the material solidify faster and improve print stability.

Important tips: A direct-drive extruder is recommended for better control. After printing, parts can be reheated locally (for example with a hair dryer or hot air gun) to bend, reshape, or bond components. Always store PCL in a sealed container with desiccant to prevent moisture absorption.

Engineering plastics are industrial-grade polymers used for functional parts, housings, and mechanical components. Compared to standard printing materials, they offer higher strength, better impact resistance, improved heat resistance, greater hardness, and longer service life.

Many engineering plastics have heat deflection temperatures above 90 °C, and printed parts can often be machined, painted, or electroplated during post-processing.

Because of these properties, engineering plastics are becoming one of the most promising categories of materials for functional 3D printing. Common examples include ABS, PA (Nylon), PC, and PEEK.

ABS (Acrylonitrile Butadiene Styrene)

ABS is a classic engineering thermoplastic widely used in manufacturing. It is known for its high strength, good heat resistance, and excellent reliability in post-processing.

Key Advantages

1.Strong and heat-resistant

ABS offers high mechanical strength and excellent impact resistance. With a heat deflection temperature close to 100 °C, it can be used for applications such as automotive interior parts or heat-resistant housings.

2.Professional-grade post-processing

ABS can be smoothed using acetone vapor, producing a glossy surface similar to injection-molded parts. It is also easy to sand, glue, and finish.

Limitations

1.Prone to warping and cracking

Large prints often suffer from corner lifting or layer separation due to uneven cooling.

2.Requires an enclosed printing environment

A heated enclosure is strongly recommended to maintain stable ambient temperature and prevent rapid cooling.

3.Strong odor during printing

ABS releases unpleasant and potentially harmful fumes when printed, so good ventilation or air filtration is necessary.

4.High bed temperature required

Reliable printing typically requires a 100–110 °C heated bed along with a suitable build surface for adhesion.

Printing Guidelines

Environment: A closed heated chamber is strongly recommended, and drafts should be avoided.

Nozzle temperature: 240–260 °C

Bed temperature: 100–110 °C

Print speed: 50–80 mm/s

Tips:Use a brim to improve bed adhesion; Avoid printing tall, thin models; Slightly increase first-layer extrusion for better adhesion

PA (Nylon)

PA, commonly known as Nylon, refers to a family of semi-crystalline polyamide engineering plastics. In 3D printing, it is valued for its exceptional strength, wear resistance, and chemical stability, making it one of the best materials for high-performance functional parts.

Key Advantages

1.Outstanding toughness and impact resistance

Among common 3D printing materials, Nylon has very high impact strength and can withstand repeated stress, shock, and fatigue without becoming brittle.

2.Excellent wear resistance

Its low friction coefficient and self-lubricating properties make it ideal for gears, bearings, bushings, and sliding components.

3.Good chemical and thermal resistance

Nylon resists oils, fuels, and many solvents, and some high-temperature variants (such as PAHT) can operate continuously at temperatures above 150 °C.

4.Strong interlayer bonding

The material flows well when molten, allowing layers to fuse strongly together, which helps reduce anisotropy and improves overall mechanical performance.

Limitations

1.Highly hygroscopic

Nylon absorbs moisture from the air very quickly. Wet filament can cause bubbles, stringing, poor surface quality, and significantly reduced strength.

2.Strict moisture control required

Proper drying and sealed storage are essential throughout storage, printing, and part usage.

3.High printing temperature and possible warping

Typical printing temperatures range from 240–280 °C, requiring an all-metal hotend. Although warping is less severe than with ABS, a heated bed and enclosed chamber are still recommended.

4.Moisture absorption in printed parts

Finished parts may also absorb moisture, which can cause minor dimensional changes or performance variation.

Printing Guidelines

Dry filament before printing: Dry the filament at 80 °C for 6–12 hours in a dedicated filament dryer.

Maintain dryness during printing: Use a dry box or filament dryer to continuously feed dry filament during the print.

Hardware requirements: It is highly recommended to print with an all-metal hotend; Hardened steel or ruby nozzle; Enclosed build chamber

Typical parameters (PA12 example):

Nozzle temperature: 250–260 °C

Bed temperature: 80–100 °C

Print speed: 40–60 mm/s

Cooling fan: Off or very low (<10%)

Post-processing: Annealing after printing can relieve internal stress, increase crystallinity, and improve dimensional stability.

Common Nylon Types in 3D Printing

PA6

A widely used industrial nylon with high strength, but high moisture absorption and more challenging printability.

PA12

The most FDM-friendly nylon. It absorbs less moisture and shows lower shrinkage and warping, making it easier to print successfully.

PA-CF (Carbon Fiber Reinforced Nylon)

Short carbon fibers increase stiffness, dimensional stability, and heat resistance, while producing a matte surface finish.

PA-GF (Glass Fiber Reinforced Nylon)

Glass fibers improve rigidity and thermal stability, usually at a lower cost than carbon-fiber variants.

PC (Polycarbonate)

PC is a high-performance amorphous engineering thermoplastic known for combining high strength, optical clarity, and strong heat resistance.

It is widely used in demanding applications such as bullet-resistant glass, aerospace visors, and high-end electronic housings. In the field of 3D printing, PC is considered a premium functional material capable of producing strong and reliable parts.

Key Advantages

1.Impact resistance

PC has one of the highest impact strengths among common 3D printing plastics. Its toughness can be 5–8 times greater than ABS, and it maintains good durability even at low temperatures without becoming brittle.

2.Thermal stability and flame resistance

With a heat deflection temperature of around 130–140 °C, PC performs significantly better than materials such as PLA or ABS in high-temperature environments. Many PC materials also meet UL94 V-0 or V-2 flame-retardant ratings, making them suitable for electronic and electrical housings.

3.Optical properties

Raw polycarbonate resin has excellent transparency, with light transmission above 90%. While the layer structure in FDM printing reduces full transparency, PC is still one of the best options for transparent or translucent functional parts.

Limitations

1.Moisture sensitivity

PC absorbs moisture easily. If the filament is not properly dried, printing may cause bubbling, popping, poor surface quality, and severe loss of mechanical strength.

2.High temperature and internal stress

PC requires very high extrusion temperatures (typically 280–310 °C). During cooling, the material shrinks noticeably and can develop strong internal stresses, which may lead to layer cracking or overall warping.

3.Demanding bed adhesion

Reliable printing usually requires specialized build surfaces or adhesives to ensure strong first-layer adhesion.

4.Hardware limitations

Many consumer-level 3D printers cannot meet the temperature and enclosure requirements necessary for stable PC printing.

5.Post-processing considerations

Annealing after printing is often recommended to relieve internal stress and improve both strength and heat resistance.

Printing Guidelines

Nozzle temperature:  290–310 °C (Start testing around 300 °C)

Bed temperature: 110–120 °C

Print speed: 30–50 mm/s. Slower speeds generally improve layer bonding strength.

Cooling fan: Turn off the cooling fan. Active cooling may cause layer cracking.

Practical tips: Slightly increase first-layer extrusion (105–110%). Use a wide brim or draft shield to improve bed adhesion and reduce warping

PEEK (Polyether Ether Ketone)

PEEK is a semi-crystalline high-performance thermoplastic widely recognized as one of the most advanced engineering polymers available.

Because of its exceptional mechanical, thermal, and chemical stability, PEEK is often used in aerospace, medical, and high-end industrial applications, and its overall performance is frequently compared to that of stainless steel and aluminium.

Key Advantages

1.Extreme heat resistance

PEEK can operate continuously at temperatures up to 260 °C, with short-term resistance exceeding 300 °C. Its heat deflection temperature can exceed 315 °C (at 1.82 MPa), making it one of the most heat-resistant thermoplastics used in 3D printing.

2.Mechanical stability in harsh environments

Even under high temperature, humidity, and chemical exposure, PEEK maintains excellent tensile strength, stiffness, and creep resistance. It also features inherent UL94 V-0 flame resistance and produces very little smoke during combustion.

3.Chemical and radiation resistance

PEEK shows excellent resistance to most organic solvents, oils, fuels, and many acids and bases (with the exception of some strong oxidizing acids such as concentrated sulfuric acid). It can also withstand high doses of gamma and X-ray radiation, which allows its use in medical sterilization and aerospace environments.

4.Wear and fatigue resistance

PEEK has a low friction coefficient and excellent wear resistance, making it ideal for high-performance seals, bearings, and sliding components. Its strong fatigue resistance also makes it suitable for parts that experience long-term cyclic loading.

5.Biocompatibility

Certain medical-grade PEEK materials meet ISO 10993 and USP Class VI standards, allowing them to be used for implantable medical devices, such as spinal implants and bone replacement components.

Limitations

1.Printing PEEK requires industrial-grade equipment:

an ultra-high-temperature hotend

a high-temperature heated bed

a fully enclosed and actively heated chamber

an all-metal extrusion path without PTFE tubing

a high-temperature build plate designed for engineering materials

2.Material preparation

PEEK filament must be kept extremely dry. Dry the filament at 150 °C for at least 8–12 hours using a vacuum or industrial filament dryer.

Maintain continuous high-temperature drying during printing

Printing Guidelines

Nozzle temperature: 380–420 °C

Bed temperature: 160–200 °C

Chamber temperature: Above 90 °C (Preferably above 110 °C for better layer bonding)

Print speed: 20–40 mm/s

Cooling fan: Cooling should remain completely disabled.

(2) Printer Performance Calibration

Understanding the relationship between materials and print parameters allows you to move beyond simply relying on preset profiles and begin optimizing the printing process independently. This section aims to help you understand how material properties influence printing behavior through several key parameters, enabling you to improve print quality more efficiently.

Before diving deeper into the theory, you may find it helpful to consult a comprehensive parameter reference. We have compiled a Material Parameter Table covering common materials such as PLA, PETG, ABS, Nylon, PC, and PEEK, based on the printing profiles of SUNLU materials.

In the following sections, we will explain how to derive optimal printing parameters from the physical characteristics of a new material. By combining these principles with practical testing, you will be able to identify the best printing settings for your setup—ultimately progressing from simply achieving successful prints to achieving exceptional print quality.

Note: Different materials (such as PLA, PETG, ABS, and Nylon) respond differently to printing parameters. The adjustment directions provided below serve as general guidelines only; actual settings should be optimized according to the specific material properties and printer configuration.

1. Temperature System Parameters

2. Motion and Extrusion Parameters

3. Cooling System Parameters

1.  Geometry and Structural Parameters

Many print quality issues are not caused by a single parameter, but rather by imbalances between multiple settings.

（4）Application Expansion

To push 3D printing beyond rapid prototyping and into functional parts and industrial applications, additional techniques are required beyond the basic printing workflow.

This section introduces several advanced topics, including environmental control, material performance optimization, and professional surface finishing techniques. These methods can help expand the practical applications of 3D printed parts.

1. Environmental Control

Reliable printing, especially with engineering-grade materials, requires a stable printing environment. The two most important factors are temperature and humidity.

Enclosures: An enclosure surrounds the printer’s build area and helps maintain a stable temperature. This is particularly important when printing materials such as ABS, ASA, PC, Nylon, and PEEK.

A stable warm environment provides several advantages:

①Reduced warping and cracking

High-shrinkage materials cool unevenly when exposed to cold air. An enclosure slows the cooling process and reduces internal stress.

②Improved layer adhesion

Warmer ambient temperatures help newly extruded plastic fuse better with previous layers.

③Less environmental interference

Airflow from air conditioners, fans, or open doors can destabilize prints. An enclosure minimizes these effects.

Humidity control is equally important. Many filaments, including Nylon, PVA, PETG, and even PLA, are hygroscopic, meaning they absorb moisture from the air.

Moisture inside filament can cause several printing problems:

l bubbling or popping during extrusion

l rough surface texture

l unstable extrusion

l nozzle clogging

In addition, wet filament often becomes weaker and more brittle. To avoid these issues, It is advisable to store filament in sealed dry boxes with desiccant and to dry wet filament using a heated filament dryer before printing.

1.  Heat Treatment

Even when a part is successfully printed under controlled conditions, its material properties are still in the as-printed state. To significantly improve mechanical strength, stiffness, heat resistance, and long-term dimensional stability, additional heat treatment may be required.

Annealing

Annealing is a post-processing heat treatment applied to finished 3D printed parts. By carefully controlling the heating and cooling process, the polymer’s molecular structure can reorganize, improving both the mechanical properties and thermal stability of the part.

Annealing is particularly valuable for functional parts that require higher strength, improved heat resistance, or long-term dimensional stability.

Key Benefits:

①Relieves internal stress and improves dimensional stability

Internal stress is one of the main causes of long-term deformation or cracking in printed parts. During annealing, heat allows the polymer chains to relax and reorganize, releasing these stresses and helping the part maintain a stable shape over time.

②Significantly increases mechanical strength and stiffness

For materials such as ABS, Nylon, and PETG, properly annealed parts can see improvements of 30% or more in tensile strength, flexural modulus, and impact resistance. The material becomes less anisotropic and behaves closer to an isotropic structure, resulting in more uniform mechanical properties.

③Raises the heat deflection temperature (HDT)

One of the most noticeable effects of annealing is an increase in heat resistance.

④Improves chemical resistance

A denser and more ordered molecular structure can better resist damage from chemical solvents and environmental exposure.

3. Surface Finishing

To achieve a high-quality appearance and professional surface texture, 3D printed parts usually require a systematic surface finishing process.

Sanding

Sanding is the basic step for removing visible layer lines, support marks, and minor surface defects.

The process typically starts with coarse sandpaper (around 240 grit) and gradually progresses to finer grits (800 grit or higher) using either dry sanding or wet sanding until a smooth surface is achieved.

For parts that require extremely smooth finishes, two common approaches are used:

Chemical smoothing

For example, acetone vapor smoothing can be applied to ABS parts. The vapor slightly dissolves the outer surface, quickly removing layer lines and producing a glossy finish. This method is very effective but must be performed with proper ventilation and strict safety precautions.

Filler sanding

Another approach is to apply model filler putty or body filler to fill layer lines. Once the filler has cured, the surface is sanded again to achieve a smooth finish. This technique works with many materials and can also increase the structural strength of the part.

Painting

Once the surface is properly prepared, the part can move on to the painting stage. Spray painting is the most common and professional method.

The first step is applying a primer. Primer helps conceal minor imperfections, improves paint adhesion, and provides a uniform base color.

Next, the topcoat is applied according to the desired finish, such as matte, gloss, or metallic effects. It is best to apply multiple thin coats rather than one thick layer to avoid paint runs.

To enhance color depth, add shading, or create weathered effects, additional model-making techniques such as brush painting, panel lining, and washes can be used for detail work.

Finally, a clear protective coat, either gloss or matte, is applied to seal the paint layer. This improves scratch resistance, adds UV protection, and gives the part its final surface appearance.