1. Overview

Additive Manufacturing refers to a group of manufacturing processes that create the desired shape by building material layer by layer. While Material Removal creates shape by removing unnecessary material, and Forming creates shape by deforming material, Additive Manufacturing creates shape by adding only the required amount of material where it is needed.

Additive Manufacturing is commonly referred to as 3D Printing, but from an industrial design perspective, it should not be understood merely as a printing technology. It is a manufacturing method that enables design freedom, prototype validation, complex geometry fabrication, lightweight structures, customized production, low-volume production, and process integration.

Representative Additive Manufacturing processes include the following.

• FDM / FFF

• SLA

• DLP

• MSLA

• SLS

• MJF

• SLM

• DMLS

• EBM

• Binder Jetting

• Material Jetting

• Directed Energy Deposition

• Sheet Lamination

The core of Additive Manufacturing is not simply “printing with a 3D printer.” Designers must consider build orientation, support structures, layer thickness, material shrinkage, thermal distortion, surface roughness, infill structure, post-processing, dimensional accuracy, mechanical anisotropy, production time, and equipment limitations together.

2. Role of Additive Manufacturing

The core role of Additive Manufacturing is to flexibly produce shapes that are difficult or uneconomical to manufacture with conventional processes.

Traditional manufacturing processes such as machining, casting, injection molding, pressing, and welding each have strong advantages, but they also have constraints related to molds, tool access, cutting depth, assembly structure, and production volume. Additive Manufacturing relaxes some of these constraints and allows designers to validate shape and function more quickly.

The role of Additive Manufacturing can be summarized as follows.

• Produces prototypes quickly.

• Enables complex internal geometries.

• Allows low-volume production without molds.

• Enables lightweight structures.

• Integrates multiple parts into a single part.

• Is suitable for customized part production.

• Responds quickly to design changes.

• Can be used as a validation tool before conventional manufacturing.

• Can be used to produce molds, jigs, fixtures, and inspection gauges.

• Can be applied to direct production of certain high-performance parts.

For example, in the early stage of machine design, 3D printing can be used to quickly produce covers, brackets, handles, sensor mounts, wiring guides, and pneumatic fitting layout jigs to review assembly and interference. Metal Additive Manufacturing can be used for molds with conformal cooling channels, lightweight brackets, complex fluid manifolds, and aerospace components.

3. Basic Principle of Additive Manufacturing

Additive Manufacturing divides 3D CAD data into layers and sequentially forms the cross-sectional shape of each layer to create the full 3D geometry.

The basic process flow is as follows.

Create 3D CAD model
→ Prepare output data such as STL, 3MF, or STEP
→ Slice the model
→ Set build orientation
→ Generate supports
→ Set machine parameters
→ Additive manufacturing process
→ Remove supports
→ Post-processing
→ Inspection

Create 3D CAD model
→ Prepare output data such as STL, 3MF, or STEP
→ Slice the model
→ Set build orientation
→ Generate supports
→ Set machine parameters
→ Additive manufacturing process
→ Remove supports
→ Post-processing
→ Inspection

Important elements in Additive Manufacturing are as follows.

The common principles of Additive Manufacturing are as follows.

• Not every shape can be made freely.

• Strength and surface quality change depending on build orientation.

• Overhangs and bridges may require supports.

• Interlayer bonding may be weaker than the material’s internal strength.

• Printed parts may have shrinkage, warpage, and residual stress.

• Precision functional surfaces may require post-machining.

• Print time is strongly affected by part height and build conditions.

4. Classification of Representative Processes

Additive Manufacturing can be classified into several processes according to material state and build method.

All of these processes build shape layer by layer, but their design criteria are different. FDM requires careful consideration of build orientation and interlayer strength, while SLA and MSLA require support and post-curing considerations. SLS requires powder removal, and metal Additive Manufacturing requires serious attention to thermal distortion, residual stress, post-machining, and heat treatment.

5. FDM / FFF

FDM / FFF is a process that heats and melts thermoplastic filament, extrudes it through a nozzle, and builds the shape layer by layer. It is one of the most widely used Additive Manufacturing methods and is commonly used for prototypes, jigs, fixtures, and simple functional parts.

Representative materials include the following.

• PLA

• ABS

• PETG

• ASA

• Nylon

• PC

• TPU

• PEI

• PEEK

• Carbon-fiber-filled filament

• Glass-fiber-filled filament

The advantages of FDM / FFF are as follows.

• Equipment and material costs are relatively low.

• Prototype production is fast.

• Various thermoplastic materials can be used.

• Large-format printing is relatively easy.

• Internal infill structure can be controlled.

• Suitable for jigs, fixtures, covers, and brackets.

The limitations of FDM / FFF are as follows.

• Layer lines appear on the surface.

• Interlayer strength may be weak.

• Dimensional accuracy is lower than machining.

• Overhangs require support.

• Shrinkage and warpage may occur.

• High-temperature materials require chamber and bed temperature control.

Designers should consider the following items.

• Build orientation

• Nozzle diameter

• Layer thickness

• Wall thickness

• Infill ratio

• Need for support

• Bridge length

• Overhang angle

• Shrinkage rate

• Warpage

• Post-processing feasibility

• Reinforcement of fastening areas

In FDM part design, the relationship between load direction and build orientation is very important. The bonding surface between layers may be weak, so the part should not be oriented so that tensile load separates the layers.

Load direction separates layers
→ Increased possibility of interlayer delamination
→ Reduced strength
→ Build orientation must be reviewed

Load direction separates layers
→ Increased possibility of interlayer delamination
→ Reduced strength
→ Build orientation must be reviewed

6. SLA, DLP, and MSLA

SLA, DLP, and MSLA are resin-based Additive Manufacturing processes that create shape by curing photopolymer resin with light. They generally provide better surface quality and detail reproduction than FDM.

6.1 SLA

SLA selectively cures the surface of resin using a laser.

The characteristics of SLA are as follows.

• Surface quality is excellent.

• Suitable for fine detail reproduction.

• Useful for precision prototype production.

• Cleaning and post-curing are required after printing.

• Resin properties may differ from thermoplastic plastics.

6.2 DLP

DLP cures an entire layer at once using a projector.

The characteristics of DLP are as follows.

• Printing speed can be fast because curing occurs by layer area.

• Resolution is affected by the projector and optical system.

• Suitable for small precision parts.

• Resin cleaning and post-curing are required.

6.3 MSLA

MSLA selectively passes UV light through an LCD mask to cure resin.

The characteristics of MSLA are as follows.

• Many affordable machines are available.

• High XY resolution can be achieved.

• Printing multiple parts at once does not significantly increase the time per layer.

• LCD lifespan and light uniformity affect quality.

• Cleaning, post-curing, and support removal are required after printing.

Design considerations for resin printing are as follows.

• Part orientation

• Support location

• Drainage holes for hollow structures

• Prevention of trapped resin

• Post-curing shrinkage

• Brittleness

• Surface quality

• Cleanability

• Minimum detail thickness

• Long-term durability

Resin printed parts have excellent appearance and detail reproduction, but they may have issues such as brittleness, thermal deformation, and long-term durability. Therefore, when they are used as functional parts, actual load, temperature, and chemical-contact conditions must be reviewed.

7. SLS and MJF

SLS and MJF are powder-based Additive Manufacturing processes that produce parts using polymer powder. Since the powder itself supports the part during printing, complex shapes can be produced without separate support structures.

7.1 SLS

SLS selectively sinters polymer powder with a laser to create the desired shape.

Representative materials include the following.

• PA12

• PA11

• TPU

• Glass-fiber-filled nylon

• Carbon-fiber-filled nylon

The advantages of SLS are as follows.

• Separate supports are not required.

• Complex internal geometries can be produced.

• Suitable for functional plastic parts.

• Multiple parts can be packed into one build.

• Material properties can be closer to isotropic than FDM.

The limitations of SLS are as follows.

• The surface is somewhat rough.

• Powder removal is required.

• Powder may remain trapped in internal closed spaces.

• Equipment and material costs are higher than FDM.

• Dimensional shrinkage compensation is required.

7.2 MJF

MJF forms parts by applying fusing and detailing agents to a powder layer and then applying heat.

The advantages of MJF are as follows.

• Productivity is high.

• Dimensional consistency is good.

• Suitable for functional plastic parts.

• Advantageous for low-volume production.

The important point in SLS and MJF design is powder removal. If internal channels or closed spaces exist, powder may remain inside. Therefore, powder escape holes and cleanability must be designed.

Complex internal space
→ Possibility of residual powder
→ Escape holes required
→ Cleaning and inspection feasibility must be reviewed

Complex internal space
→ Possibility of residual powder
→ Escape holes required
→ Cleaning and inspection feasibility must be reviewed

8. Metal Additive Manufacturing

Metal Additive Manufacturing is an Additive Manufacturing process that directly produces metal parts using metal powder or metal wire. It can be applied to complex metal geometries that are difficult to produce by ordinary machining or casting.

Representative metal Additive Manufacturing processes include the following.

• SLM

• DMLS

• EBM

• Binder Jetting

• Directed Energy Deposition

• Wire Arc Additive Manufacturing

Representative metal materials include the following.

• Stainless steel

• Aluminum alloys

• Titanium alloys

• Nickel alloys

• Tool steel

• Cobalt-chrome alloys

• Copper alloys

The advantages of metal Additive Manufacturing are as follows.

• Complex internal flow paths can be produced.

• Lightweight lattice structures can be implemented.

• Mold cooling channels can be optimized.

• It is useful in aerospace, medical, and tooling applications.

• Assembly part count can be reduced through part integration.

• Suitable for high-value low-volume production.

The limitations of metal Additive Manufacturing are as follows.

• Equipment and material costs are high.

• Thermal distortion and residual stress are significant.

• Support removal is difficult.

• Surface roughness can be high.

• Post-machining and heat treatment are almost essential.

• Quality verification is difficult and expensive.

• Large parts face major equipment-size and distortion problems.

Designers should consider the following items.

• Build orientation

• Thermal distortion

• Support removal feasibility

• Residual stress

• Post-heat treatment

• Need for HIP treatment

• Post-machining of precision functional surfaces

• Internal defect inspection

• Surface roughness

• Powder removal

• Separation from build platform

• Production cost

In metal Additive Manufacturing, “printable” and “usable as a functional part” are different. A metal printed part should be evaluated as a final part only after considering heat treatment, stress relief, support removal, CNC post-machining, surface treatment, and non-destructive inspection.

9. Binder Jetting and Material Jetting

9.1 Binder Jetting

Binder Jetting creates shape by selectively jetting binder onto a powder layer. The final part is produced through post-processing steps such as curing, debinding, sintering, and infiltration.

The advantages of Binder Jetting are as follows.

• Relatively fast production is possible.

• Supports are rarely required.

• It can be applied to various powders such as metal, ceramic, and sand.

• It has potential for mass production.

• It is also used to produce sand molds for casting.

The limitations of Binder Jetting are as follows.

• Sintering shrinkage is large.

• Dimensional prediction is difficult.

• Density and strength must be secured.

• Post-processing is complex.

• Precision functional surfaces require post-machining.

9.2 Material Jetting

Material Jetting jets liquid resin or wax-like material using an inkjet method and cures it with light or heat to create shape.

The advantages of Material Jetting are as follows.

• Very high resolution can be achieved.

• Multi-material printing is possible.

• Color and transparent material representation are possible.

• Suitable for visual prototype production.

• Fine detail reproduction is excellent.

The limitations of Material Jetting are as follows.

• Material properties are limited.

• Equipment and material costs are high.

• It is often more suitable for visual validation than functional parts.

• Support removal is required.

10. DED and Large-Scale Metal Deposition

Directed Energy Deposition, DED is a process that deposits metal powder or wire by feeding the material while melting it with energy such as a laser, electron beam, or arc.

Representative applications of DED include the following.

• Metal part repair

• Large metal part deposition

• Restoration of worn areas

• Repair of high-value parts

• Multi-material deposition

• Mold repair

• Aerospace part repair

The advantages of DED are as follows.

• Suitable for large metal structures.

• Material can be added onto existing parts.

• Useful for repair and restoration.

• Deposition speed can be relatively high.

• Can be combined with robotic systems.

The limitations of DED are as follows.

• Surface quality is low.

• Precision is low, so post-machining is required.

• Thermal distortion and residual stress are significant.

• Process control is difficult.

• It may be unsuitable for high-precision complex geometry.

DED should be understood more as a hybrid manufacturing method that deposits metal into a near-net shape and then finishes it by machining, rather than as a process that directly produces final dimensions.

11. Design Criteria: Design for Additive Manufacturing

Additive Manufacturing requires design criteria different from conventional manufacturing. This is called Design for Additive Manufacturing, DfAM.

The core criteria of DfAM are as follows.

11.1 Build Orientation

Build orientation affects strength, surface quality, support requirements, print time, and distortion.

Determine build orientation
→ Determine strength direction
→ Determine support amount
→ Determine surface quality
→ Determine print time

Determine build orientation
→ Determine strength direction
→ Determine support amount
→ Determine surface quality
→ Determine print time

11.2 Support Minimization

Overhangs, bridges, and protruding structures may require supports. Supports must be removed after printing and increase surface damage and post-processing cost.

11.3 Minimum Wall Thickness

Each process and material has a minimum printable wall thickness. Walls that are too thin may break during printing or deform during post-processing.

11.4 Internal Structures

Additive Manufacturing can create lattice structures, internal channels, and hollow structures. However, internal powder, resin, or supports must be removable.

11.5 Tolerance and Fit

The dimensional accuracy of Additive Manufacturing differs depending on the process. Assembly parts must be designed while considering clearance, shrinkage, post-processing, and surface roughness.

11.6 Post-Machining Datum Surfaces

Precision functional surfaces may not be sufficient in the as-printed state. Bearing mounting surfaces, sealing surfaces, fastening surfaces, and datum surfaces must have machining allowance and tool access for post-machining.

11.7 Escape Holes

Hollow structures or internal channels require escape holes for removing residual resin, powder, or support material.

12. Build Orientation and Mechanical Properties

Additive Manufacturing parts may have different mechanical properties depending on build orientation. In particular, directional strength differences are important in FDM and metal Additive Manufacturing.

Build orientation affects the following items.

• Tensile strength

• Bending strength

• Impact strength

• Fatigue life

• Interlayer delamination

• Surface quality

• Dimensional stability

• Support requirements

In FDM, bonding between layers may be weak. In metal Additive Manufacturing, microstructure, residual stress, and defect orientation may also depend on build direction.

Same geometry
→ Change build orientation
→ Change strength direction
→ Change surface quality
→ Change support and cost

Same geometry
→ Change build orientation
→ Change strength direction
→ Change surface quality
→ Change support and cost

Therefore, designers should determine build orientation based on the actual load direction applied to the part. Surfaces where appearance is important, surfaces requiring post-machining, and surfaces where support removal is difficult should also be considered.

13. Support and Post-Processing

In Additive Manufacturing, supports are often essential for print success, but they also create cost and quality issues.

Supports are typically required in the following cases.

• Large overhangs

• Long bridges

• Floating geometry

• Thin and long protrusions

• Prevention of thermal distortion in metal Additive Manufacturing

• Fixing to the build platform

Problems caused by supports include the following.

• Removal time is required.

• Surface damage occurs.

• Removal can be difficult in internal structures.

• Material waste increases.

• Print time increases.

• Removal cost is high in metal Additive Manufacturing.

Post-processing differs by process.

Good Additive Manufacturing design does not simply aim to eliminate supports completely. It controls where supports are needed and arranges the shape so that post-processing is possible.

14. Tolerance, Surface Quality, and Precision

Additive Manufacturing has high geometric freedom, but not every process provides high precision. Dimensional accuracy and surface quality vary greatly depending on printing method, material, equipment, build orientation, and post-processing.

Factors affecting tolerance and quality include the following.

• Equipment resolution

• Nozzle diameter

• Laser spot size

• Pixel size

• Layer thickness

• Material shrinkage

• Thermal distortion

• Support removal

• Post-curing

• Powder sintering shrinkage

• Machine calibration

• Print orientation

Designers should consider the following criteria.

• Post-machining should be considered for precision fits.

• Fastening holes can be drilled or reamed after printing.

• Bearing mounting areas are difficult to make precise by printing alone.

• Sealing surfaces may require post-machining or polishing.

• Surface roughness should be managed separately for functional and appearance surfaces.

• Dimensional tolerances should be specified within process capability.

Printed geometry
→ Basic shape secured

Post-machining
→ Precision dimensions and functional surfaces secured

Printed geometry
→ Basic shape secured

Post-machining
→ Precision dimensions and functional surfaces secured

In Additive Manufacturing, the realistic approach is not to complete precision by printing alone, but to complete necessary functional surfaces by combining printing with post-machining.

15. Defects and Quality Issues

Additive Manufacturing can create defects specific to layer-based manufacturing.

Representative defects include the following.

These defects are not only machine problems. They are directly connected to build orientation, wall thickness, support location, internal structure, material selection, post-processing feasibility, and inspection method.

16. Additive Manufacturing and Post-Machining

Additive Manufacturing parts may be used as printed, but functional parts often require post-processing or post-machining.

Representative post-processing operations include the following.

• Support removal

• Powder removal

• Resin cleaning

• UV post-curing

• Heat treatment

• Stress relief

• CNC machining

• Drilling

• Tapping

• Reaming

• Grinding

• Sandblasting

• Surface coating

• Painting

• Inspection

Metal Additive Manufacturing parts in particular often include CNC machining and heat treatment after printing. Bearing mounting surfaces, bolting surfaces, sealing surfaces, and datum surfaces may not be sufficient in the as-built condition.

Additive Manufacturing
→ Produces complex basic geometry

Post-Machining
→ Completes precision functional surfaces

Additive Manufacturing
→ Produces complex basic geometry

Post-Machining
→ Completes precision functional surfaces

Designers must review whether post-machining tools can access the part after printing, whether machining datum surfaces can be established, and whether sufficient machining allowance is available.

17. Production Volume and Economic Feasibility

Additive Manufacturing is strong in prototypes and low-volume production because it does not require molds. However, because printing time can be long and equipment cost can be high, it is not always economical for mass production.

The relationship between production volume and Additive Manufacturing can be summarized as follows.

Prototype / low-volume production
→ No mold cost
→ Easy design changes
→ Additive Manufacturing is advantageous

Mass production
→ Printing time accumulates as cost
→ Injection molding, casting, or pressing may be advantageous

Prototype / low-volume production
→ No mold cost
→ Easy design changes
→ Additive Manufacturing is advantageous

Mass production
→ Printing time accumulates as cost
→ Injection molding, casting, or pressing may be advantageous

When selecting Additive Manufacturing, the following cost elements should be reviewed.

• Machine usage cost

• Material cost

• Print time

• Support material

• Post-processing time

• Failure rate

• Inspection cost

• Post-machining cost

• Possibility of design change

• Mold cost replacement effect

• Inventory cost reduction effect

• Part integration effect

Additive Manufacturing may look expensive if evaluated only by unit part price. However, when mold cost reduction, reduced assembly part count, shorter development time, reduced inventory, and customized production are included, it can be advantageous in total cost.

18. Application of Additive Manufacturing in Food Machinery

In food machinery and meat-processing machinery, Additive Manufacturing can mainly be used for prototypes, jigs, non-contact parts, covers, guides, sensor brackets, wiring guides, and test parts.

Representative applications include the following.

• Prototype covers

• Sensor brackets

• Wiring guides

• Assembly jigs

• Inspection jigs

• Pneumatic piping alignment jigs

• Non-contact protective covers

• Test guides

• Ergonomic handle prototypes

• Customized tool holders

When applying Additive Manufacturing to food machinery, the following should be considered.

• Whether the material is suitable for food contact must be confirmed.

• Contamination may remain between layer lines.

• Surface roughness may reduce cleanability.

• Cleaning liquid or contamination may be trapped in internal voids.

• Wear particles from resin or plastic must be considered.

• The material must withstand high-temperature cleaning and cleaning agents.

• Long-term durability of the printed material must be reviewed.

• Food-contact parts may require post-processing and certification.

Therefore, direct application of Additive Manufacturing to food-contact parts requires great caution. Surface roughness, cleanability, material certification, chemical resistance, wear, and the possibility of foreign-material generation in case of breakage must be reviewed.

19. Connection with Other Knowledge Tracks

Additive Manufacturing is closely connected with other Knowledge Tracks.

19.1 Connection with Material

Material determines printability, strength, heat resistance, shrinkage, surface quality, and post-processing.

Material
→ Determines printability, strength, shrinkage, and heat resistance

Additive Manufacturing
→ Builds shape by stacking material layer by layer

Material
→ Determines printability, strength, shrinkage, and heat resistance

Additive Manufacturing
→ Builds shape by stacking material layer by layer

19.2 Connection with Mechanism & Motion

In moving parts, build orientation, surface roughness, friction, wear, and fatigue life are important. Printed gears, links, cams, and guides must be reviewed under actual load and repeated motion conditions.

Mechanism & Motion
→ Defines load, friction, and repeated motion conditions

Additive Manufacturing
→ Offers high geometric manufacturability, but strength and wear must be verified

Mechanism & Motion
→ Defines load, friction, and repeated motion conditions

Additive Manufacturing
→ Offers high geometric manufacturability, but strength and wear must be verified

19.3 Connection with Assembly

Additive Manufacturing is useful for integrating multiple parts into one part or producing assembly-support jigs. However, fastening areas, inserts, taps, and assembly tolerances must be considered.

Additive Manufacturing
→ Produces part integration, assembly jigs, and custom fixtures

Assembly
→ Reviews fastening, positioning, and assembly tolerance

Additive Manufacturing
→ Produces part integration, assembly jigs, and custom fixtures

Assembly
→ Reviews fastening, positioning, and assembly tolerance

19.4 Connection with Manufacturing Quality

Additive Manufacturing can involve layer defects, internal defects, dimensional variation, and surface quality issues, so inspection criteria are important.

Additive Manufacturing
→ Manages build orientation, support, shrinkage, and internal defects

Manufacturing Quality
→ Performs dimensional inspection, surface inspection, internal defect inspection, and functional verification

Additive Manufacturing
→ Manages build orientation, support, shrinkage, and internal defects

Manufacturing Quality
→ Performs dimensional inspection, surface inspection, internal defect inspection, and functional verification

20. Core Thinking

The core thinking in Additive Manufacturing is as follows.

Geometric freedom is high, but manufacturing constraints still exist.

Build orientation determines strength, surface quality, support, and cost.

Printability and usability as a functional part are not the same.

Overhangs and internal structures must consider supports and post-processing.

Interlayer bonding can become a weak point.

Precision functional surfaces may require post-machining after printing.

In metal Additive Manufacturing, post-processing and inspection cost may be more important than printing itself.

Resin printed parts have good appearance but require review of brittleness, thermal deformation, and long-term durability.

In food machinery, cleanability of layered surfaces and material suitability are important.

Additive Manufacturing is strong in prototypes and low-volume production, but it must be compared with conventional manufacturing for mass production.

Good Additive Manufacturing design considers build orientation, support, material, post-processing, assembly, and inspectability at the same time.

21. Conclusion

Additive Manufacturing is a group of manufacturing processes that create the desired shape by building material layer by layer. Processes such as FDM, SLA, DLP, MSLA, SLS, MJF, metal Additive Manufacturing, Binder Jetting, and DED have strong advantages in prototyping, complex geometry fabrication, low-volume production, customized production, and part integration.

However, Additive Manufacturing is not simply a technology for outputting shapes with a 3D printer. Designers must consider build orientation, supports, interlayer strength, surface roughness, shrinkage, thermal distortion, internal structures, post-processing, post-machining, and inspectability together.

From the mechanical design perspective, the key points of Additive Manufacturing are as follows.

• Is this part functionally suitable for Additive Manufacturing?

• Is the build orientation suitable for the actual load direction?

• Can supports be removed and post-processing performed?

• Can precision functional surfaces be post-machined?

• Will powder, resin, or contamination remain inside internal structures?

• Are the material properties suitable for the actual operating conditions?

• Is the balance between printing cost and production volume appropriate?

• Does Additive Manufacturing provide advantages over conventional manufacturing in design, cost, or lead time?

Therefore, Additive Manufacturing is a core section in the Manufacturing Track that expands design freedom and manufacturing flexibility. It is closely connected with Material, Mechanism & Motion, Assembly, and Manufacturing Quality.