Essential Tips for Designing Parts for FDM 3D Printing

Considered one of the most widely adopted 3D printing techniques, fused deposition modeling (FDM) 3D printing has changed how people manufacture or prototype objects since it is much easier and cheaper to transform intricate geometry into physical components. Still, it is necessary to consider some important design considerations to utilize FDM technology effectively. In this tutorial, we will focus on the design process for FDM 3D printing and present many practical considerations about print, strength, and efficiency. Whether you are a professional in the design field or a novice, these ideas will offer a solid platform for designing, considering FDM 3D printing.

What is FDM 3D Printing?

Understanding FDM Technology

Fused deposition modeling (FDM) is an additive manufacturing technique that produces sculptural forms by the deposition of steps of workpiece layer by layer of thawing-thermosetting material filament. The filament is pushed through a nozzle head, which heats the filament to melt and then extrudes it in a predefined manner as designed for the printer. The printer’s working staircase keeps dipping as new levels are being extruded, and therefore, the part is being formed. Many users of the FDM technology appreciate the production of stable and well-functioning parts made of a wide range of materials – from common PLA to advanced engineer-grade thermoplastics. This approach achieves exceptionally high efficiency for rapid prototyping, custom parts manufacturing, and producing end-use components with particular mechanical features.

How FDM Prints are Created

Every FDM print originated in 3D models, which are more often than not generated using CAD software. After completing this design phase, the file is saved in G-code, which details how a 3D printer will fabricate the part. The melted thermoplastic filament is first deposited into a constricted extrusion nozzle to heat it to its melting point. The extruder moves in the direction specified in G-codes and spreads the hot fluid polymer material in layers over a platen dowel. Each layer is allowed to harden after components of the next layer are placed on it, plus the platform is lowered a little each time. This continues until the required part is built up to the last detail and the manufactured item has the correct geometry and dense properties.

FDM vs. Other 3D Printing Technologies

Fused Deposition Modeling (FDM) is unique compared to the other types of 3D printer technologies in some important ways. FDM is less expensive and easier to operate Canadian bacon than SLA, which employs liquid resin cured with ultraviolet light but tends to have a lower resolution and surface finish. Selective Laser Sintering (SLS), which involves generating heat through a laser-compacted powder material, gives very good mechanical and functional properties and can make more complicated shapes than SLS, although at a higher cost additional processing is required. Digital Light Processing (DLP) still possesses the features of an SLA, but this technique uses a digital light projector screen. It is somewhat weak for its parts more than the FDM, but this method still produces excellent details and a smooth surface. Overall, it can be said that FDM can be bought at an economical price, is made of many types of material, and is sturdy, thus able to do rapid modeling or functional use at the end of the day with some cost in quality of detail and surface smoothness.

What are the Key Design Guidelines for FDM 3D Printing?

General Design Guidelines

The following recommendations will assist every designer in minimizing the risk of possible defects and improving the quality of the model when constructing the three-dimensional printing design.

1. Wall Thickness: First, the minimum wall thickness that must always be adopted when designing for optimal strength and support for the model is 1-2 mm. A very low wall thickness may result in undesired or no parts.
2. Overhangs and Angles: Since FDM printers work on building parts layer by layer, starting from the base, the overhangs closer to 45 degrees will be subjected to supports. Maintaining angles lower than the latter is preferable as it lessens the number of supports while achieving efficiency.
3. Layer Height: Layer heights must be precise so that prints are of good quality and the time taken to print any given item is reduced. For instance, smaller layer heights (e.g., 0.1 mm) produce finer details while taking longer to print, while layer heights (e.g., 0.3 mm) help advance the process faster, although some details might be lost.
4. Infill Density and Pattern: If the parts appear too wide, they can be made denser than necessary, but if they are thin, the infill can be made less dense than required. Common infill patterns are, e.g., honeycomb and grid, which achieve a trade-off between the actual strength of the model and the time taken to put it in print. In most cases, 20-30% fill is adequate for most applications.
5. Bridging: In 3D printing, where the printer has to bridge gaps of several points, efficient bridging elements that increase the reliability of the object are needed. Figuring out how long the distance a bridge can be without compromising the accuracy of the model relates to the printer’s capability.
6. Orientation: The part’s placement on the build platform substantially influences its integrity, surface finish, and the number of support structures needed. Evolve the model so that minimal overhangs and optimal layer bonding are achieved.
7. Hole Diameters: It is recommended that holes slightly bigger than what is needed be designed to allow for shrinkage and thus be printed to the appropriate size.

These design principles can be extremely beneficial in achieving better-quality prints, enhanced reliability, and less material and time waste.

Designing for FDM Strength

In Fused Deposition Modeling (FDM), designing for strength involves considering several important factors in light of the most recent and advanced printing technology available in the market. Firstly, material selection is crucial for the strength of the printed part; some parts of the printer can be made from Nylon or Polycarbonate (PC) or composites laminated with carbon fiber instead of regular PLA or ABS to withstand more tensile and impact force.

Secondly, it is essential to improve the printing parameters. This includes increasing the wall thickness and improving the part’s durability. Also, increasing infill density provides additional internal support, causing an upsurge in strength. Other filler patterns, such as the grid or honeycomb, are filled in the midsections of components, which help to counteract the stresses.

Last but not least, the print orientation is another important aspect because of the interlayer bond property. The best orientation should be made to the model so that the line of action and the layer line coincide. Such positioning reduces the stress concentration and improves the tensile stress of that part of the print where it is most needed along two or three axes. This ensures that FDM printing will produce strong and dependable outputs.

Optimizing Print Orientation

Adjusting print orientation parameters is crucial in Fused Deposition Modeling (FDM) as it ensures the printed part’s required strength and surface finish. The orientation directly impacts the mechanical strength, surface quality, and support material utilization.

1. Mechanical Strength: Layers should be oriented to bear the maximum load of the part. Ideally, print layers should be oriented parallel to the direction of tension to strengthen the tensile load and eradicate the possible concentration of weak links between layers.
2. Surface Quality: Layer orientation can affect the scope of the layer lines and the smoothness of the surfaces. It is useful to place the part so that there are few overhangs and support structures for a better surface finish and less post-processing.
3. Support Material Usage: Proper orientation of the part can help eliminate or lessen the need for the supporting structure, making the procedure faster, using less material, and simplifying the problem of removing supports. It also decreases the chance of creating surface defects at the contact points with the supporting structures.

Therefore, after critically assessing the parameters mentioned above and using the slicing software to rotate the model to obtain the new orientation, designers can enhance print orientation for suitable strength, better surface quality, and efficient material use.

What Materials Can Be Used in FDM 3D Printing?

Common FDM Materials

As far as fused deposition modeling (FDM) 3D printing technology is concerned, several materials can be identified, each with certain characteristics that are ideal for the specific application. PLA, ABS, and PETG are the most proven technologies that FDM is looking to progress on.

1. PLA (Polylactic Acid): PLA is a biodegradable thermoplastic polymer made from corn starch or sugarcane. It is more user-friendly, can be printed at lower temperatures than the others, and minimizes warping. Hence, PLA is best for prototyping, learning institutions, and situations within which the designs made by the FDM part do not require much flexibility.
2. ABS (Acrylonitrile Butadiene Styrene): It is a strong thermoplastic that is rugged, shock-absorbent, and has high heat resistance. Then, it also requires a relatively well-defined temperature range and enclosed environment, at least during some phases of the printing process, to avoid deformation or cracks. ABS can fabricate functional parts, automotive parts, and toys using the FDM technique.
3. PETG (Polyethylene Terephthalate Glycol-Modified): PETG offers users the same Command of the printer as PLA but also the toughness and durability of ABS. It is very chemically resistant, tends to deform less than others, and achieves a better surface finish. Therefore, PETG parts find applications in mechanical components, casing, and containers meant for food.

Users are equipped to enhance their performance and obtain the desired results in their FDM 3D printing projects using suitable materials based on the characteristics of the print.

Choosing the Right Material for Your Part

For any FDM 3D printing undertaking, it is essential to choose the right material, considering various aspects such as the mechanical aspects to be achieved, the surroundings’ conditions, and the nature of the load on the part.

1. Understand Your Requirements: Determine whether the part requires flexibility, endurance, or some degree of flexibility and strength. If you need very high stiffness and minimal warping, then PLA will probably be good. However, ABS is best for impact resistance and higher heat distortion temperature. PETG suits parts requiring strength, flexibility, and chemical resistivity.
2. Consider the Print Environment: Know the working conditions in which the print will be done and the settings of the machine. PLA is easy to print as it prints at lower temperatures and does not require a heated bed, which is ideal for a newbie. In contrast, ABS requires a heated bed and better airflow because of fumes emitted while printing. The situation with PETG is similar, but this material also needs a heated bed, which makes things easier than with ABS in terms of printing warping and odor.
3. Application-Specific Concerns: For parts that come into contact with harsh conditions or chemicals, PETG performs better than other types of polymers. However, PLA is adequate for educational models or prototypes, emphasizing easy printing and post-processing. ABS is common for some functional parts where more strength and impact resistance are required.

Considering these aspects, users can choose the material most appropriate for their particular needs and the FDM 3D printing process, ensuring the quality and performance of the printed parts.

Material Properties and Behavior

In the context of the FDM 3D printing process, as well as the understanding and characterization of the material properties and behaviors, several aspects stand out:

1. PLA (Polylactic Acid): It is important when considering PLA because it is straightforward to use and thus excellent for children. The softening temperatures are low (usually in the 190-220°C), and no warming plates are used when printing such models. It is generally odorless. The material cannot warp much and has good strength and rigidity. On the downside, it does not have suitable heat resistance and impact resistance properties like most plastic parts, making them unfit for use as functional parts.
2. Generally refers to ABS and Acrylonitrile Butadiene Styrene plastic that is impact resistant and therefore secure for many tasks. The extrusion occurs at relatively higher temperatures of about 220-250 degrees, with the need for a heated bed while printing it to avoid deformation of the plastic mold (about 90-110°C). While it produces fumes and odors, the extruded filament of the plastic requires good ventilation when working. It has been found to exhibit better impact and heat resistance than PLA when printed on, although it is worth noting that the print may be difficult owing to warping.
3. PETG (Polyethylene Terephthalate Glycol): PETG is as easy to work with as PLA while offering the strength of ABS. It can be printed at a temperature of 220-2500C, and a heated bed of around 70-90 0C is commonly used. PETG has good adhesion between layers, good toughness, and chemical resistance, so it is used for various applications. Worrying about Perfect warping is not an issue, nor is the fuming as bad as ABS. Thus, it serves many 3D print application needs herein.

Understanding all these reinforcing materials’ properties and behaviors, users can predict which materials would be the best to use among the pieces of equipment in FDM 3D printing.

What are the Best Practices for Designing an FDM Part?

Minimizing Print Failures

Several strategies should be implemented to avoid failures during FDM 3D printing:

1. Optimize Print Settings: Adjust parameters such as layer height, print speed, and extruder temperature to the set material requirements. Doing this for every print makes the prints much more tolerable, as there are minimal complications such as under-extruding or overheating.
2. Ensure Bed Adhesion: Like glue sticks or painter’s tape, these adhesives can be placed on the surface of the build plate, or, in some instances, a heated bed can be used for better bed attachment. Wrong bed leveling contributes to malformations in the spools and disconnection of the print.
3. Maintain Equipment: One major cause of poor-quality prints is the failure to maintain 3D printers, such as cleaning the nozzle and the print bed and ensuring movement mechanisms are properly oiled and in good working order.
4. Use Quality Materials: FDM filament for typical users should not be disposable, and such high-grade HDPE rarely causes jamming or inconsistencies. Filaments should also be kept from damp places, where moisture can lead to defective prints.
5. Design Considerations: Constructing parts with adequate support features, even wall sections, and minimizing the overhang angles will make printing easier without mistakes. Tiny parts and many with complex structures may be best avoided for the printer.

Adopting these best practices will raise the success rate of FDM 3D printing, yielding dependable and commendable prints.

Designing for Print Time Efficiency

To execute strategies that enhance the print time in the FDM 3D Printing Application, the following factors must be put into consideration:

1. Optimize Infill Percentage: One way to reduce the time it takes to print an object is to lower the infill percentage while maintaining the part’s structural strength. The range most often used is 10% to 20%, depending on how strong the end part needs to be.
2. Layer Height Adjustments: Increasing the layer height means depositing fewer layers, speeding up the printing. However, the final resolution may have been slightly sacrificed and will also depend on the type of application for which the print is meant.
3. Simplify Geometry: Do not include complicated sections and details requiring additional support material and effort to print. When printing, use as basic and less complicated designs as possible.
4. Effective Use of Support Structures: Place the model in the correct position on the build plate to minimize the support structures used. Decreasing the amount of support material not only cuts time but also expenses.
5. Print Multiple Objects Strategically: If several parts are to be printed, the orientation of the parts should be such that print head travel movements that add no value to the print are minimized, reducing the total time taken for every print.

Such design strategies for 3D-printed parts can enhance design turnaround times, which in turn results in faster production rates without necessarily sacrificing the quality of the end product.

How to Address Design Constraints in FDM Printing?

Managing Overhangs and Supports

Here are a few suggested strategies on how to address overhangs and supports in FDM printing:

1. Plan the Design Knowing Overhang Limits in Advance: An FDM printer can only print overhangs up to approximately 45 degrees. Designing parts with any overhangs in this range usually means no supports are needed.
2. Use Chamfers and Filters: The sharp profile of the overhanging edge can be replaced by more rounded details to lower its inclination angle, which will help in printing parts without supports.
3. Implement Tree Supports: In cases where overhangs cannot be avoided, tree supports would be better than conventional grid supports because they are more efficient. Less material is used, and fewer resources are spent on removal.
4. Optimize Support Parameters: Altering multipliers of support filling, filler patterns, and the number of interface layers in your slicing program can lessen the opportunity to waste the materials required for the supports and the level of assistance offered for overhangs, which helps turn that angled structure back decently.

Given these strategies, designers can find a suitable combination of strategies to meet the needs of overhangs and ensure the final efficiency and quality of the printed part.

Designing Separate Parts

Some basic rules should be followed when creating such parts if forest assembly as efficiently as possible and the quality of prints is to be maximized:

1. Interlocking Features: Create interlocking features, such as pins or slots and dovetail joints, to make the parts easier to assemble and offer increased strength. Therefore, a strong physical and spatial bond of accident components is possible without the use of adhesives or fasteners in the 3D printing service.
2. Alignment and Tolerances: No excessive gaps or overlaps are present, and features interchangeable with each other are provided. Although reasonable tolerances have to be set for the dimensional specifications of these FDM components, such tolerances should factor in the printer’s resolution and what is perceived as a borderline dimensional variation.
3. Sectional Design: Divide larger parts into several smaller subparts that do not cause problems with the printing and subsequent assembly process. This manner of designing accelerates the production cycle since the processing of the parts is also straightforward.
4. Minimize Assembly Steps: Construct parts so that many actions to enhance the disjointed parts are unnecessary. It is, therefore, apparent that with minimal parts assembled, the assembly procedure is much faster and easier, and all these ginsengs can lead to great time and cost reduction in the 3D printing service.

These principles of basic thinking should help designers withstand design restrictions and achieve the printing of dimensionally acceptable and functional parts using FDM technology.

Addressing Tolerance and Fit Issues

In the same process that affects various tolerances and fittings regarding the FDM process, some solutions should be applied to ensure the accuracy and functionality of 3D-printed components:

1. Design for Manufacturability (DFM): Consider the capacities and constraints of the particular FDM printer. Knowing what the machine is capable of will help identify reasonable tolerances.
2. Calibration and Compensation: Regularly calibrate the printer to standardize its operations. Modify the designs to account for deviations like shrinkage or warping, which are common with FDM prints.
3. Post-Processing Techniques: Perform fitting aids between components by refining joints with sanding, drilling, precision engagement, and other similar pre-laitance operations. These rectification operations can help compensate for small changes missed during the FDM process and achieve positive tolerancing for the 3D-printed components.

Adhering to these procedures, designers can find workable solutions to tolerance and fit concerns, and the overall assembled article will be functional and aesthetically appealing.

Reference Sources

3D printing

Extrusion

Printer (computing)

Kingsun’s 3D Printing Service for Custom Parts

Frequently Asked Questions (FAQs)

Q: What do you Remember while constructing an FDM Fused Deposition Modeling 3D printer?

A: When designing for an FDM 3D printer, the following key aspects need to be considered: part orientation, support structures, wall thickness, and overhangs. Overhangs need to be kept to a minimum, supportive angles should be designed, and printer resolution must be taken into account. In addition, the functionality of the final part should be considered, and how 3D printing technology would change its integrity and external appearance should be considered.

Q: How does FDM impact how parts would be designed?

A: Because the layer-by-layer construction of parts characterizes FDM printing, such construction can impact the design in multiple ways. For example, layer orientation to achieve strength should be considered, the use of support structures needs to be restricted as much as possible, and parts that are to be manufactured should, in all cases, not involve too many overhangs. Since FDM is inherently a layer-based process, it can lead to some degree of surface degradation, which means that it is important to think ahead of time about what needful surfaces will require in terms of post-processing.

Q: Are there basic design rules that apply to FDM?

A: Some general FDM design considerations will be the following: ensuring that certain minimum wall thicknesses are met, usually 0.8-1mm or so, creating self-supporting angles (more than 45 degrees to the vertical), avoiding depots of large flat areas overhanging supports, avoiding notch effect through the use of fillets and chamfers, incorporating functional features in the model. Besides, it is always good to design holes slightly smaller than they should be; for instance, they may later be exposed to final reaming after the hole has been printed.

Q: How should I improve my design for efficient FDM printing?

A: To address the optimization issues while designing for FDM, it is recommended first to identify the main part and then consider whether it is necessary to break it into a few logical pieces and focus on the area anchoring to the supporting structures. Use design features such as bridges and fillets to avoid using up material in excessive supports in your FDM components. Also, examine the various features critical in the design and aim at the most appropriate print direction to improve the surface quality and strength of the components in most cases.

Q: What are the limitations of FDM 3D printing that affect design?

A: Designers need to acknowledge some limitations with FDM. These are less resolution than any of the other 3D printing methods, layer lines that can be visible after completing the model, large and flat surfaces that may cause warpage, and the anisotropic strength characteristics of the material. The process also does not cope with small details and tends to need support material for any overhangs, which would frequently spoil the surface of the part to which the supporter is attached.

Q: How should I understand the task of designing functional parts for FDM 3D printing processes?

A: Focus on the main function of the FDM part, look at how the part is printed, and consider how it is expected to work. Think about the position of load-bearing elements. Design the assembly: If several items are joined together, tolerance should be applied to the mated parts’ surfaces. It is usually a good idea to add post-processing-friendly features, such as making holes smaller for a precise fit when eventually drilled out.

Q: What design features should I avoid when creating parts for FDM printers?

A: Design aspects such as sharp internal corners, which tend to gather stress, should be avoided in FDM printer designs, as well as fragile walls or elements that may be printed but lack any integrity. Large overhangs or bridges that protrude out too extensively should be avoided as these may sag or call for thick support structures towards the overhanging end. Parts concerning areas with features perpendicular to the Z-direction axis should also be evaded since the layer lines of the parts would be apparent along the Z-direction axis and may compromise the structural strength.

Q: How can I design parts to minimize the need for support structures in FDM printing?

A: Some specific angles, often quite obtuse, should be built into the parts to avoid any overhanging geometry and, thus, the necessity for supports. These sorts of edges should either be chamfered or chopped off, and any overhanging attitude should be repositioned to avoid using supports. The necessity of establishing support to maintain the overhang depends on the part’s orientation to the extent that such an overhang exists. When appropriate, using supports, the geometry will permit the structures to be used and present no hazardous acute surfaces to critical zones of the structures.