By Todd Grimm, Editor

In Short
  • 3D printing is the most diverse engineering and manufacturing technology.
  • Breadth of technologies represented by six core processes.
  • Define your needs, wants and desires. Then start your evaluation with a review of the characteristics of the core processes.

There is no other manufacturing technology as diverse as 3D printing. It encompasses many technologies and process and each has different attributes. In terms of conventional approaches, only machining comes close to the breadth and range of options. Yet, even machining is constrained to one core method, material removal with a cutter. 3D printing has no such constraint.

3D printing spans:

  • $500 kits to $1,000,000 systems
  • Micro-parts to massive tools
  • Plastic, metal, ceramic, wax, glass, sand and paper

The diversity within 3D printing offers options that work for a wide range of applications in an equally wide range of industries. This gives you unparalleled choice and a wealth of options that allow you to match a 3D printing technology to your needs.

The downside of all these option is that things can get confusing, quickly. With so many choices, where do you start? How do you find the one technology that is right for you?

First, forget about finding the one technology that is best. Instead, aim for a system that can handle the most applications that you will have in the coming years. I’ve long said that 3D printers aren’t truly competitive to one another (for the most part). Those that truly excel, those that are doing the most amazing things, have a stable of technologies from which to choose. They match 3D printer performance to the job at hand.

The one thing that all 3D printers have in common is that they grow parts on a layer-by-layer basis. That basic element is what makes it unique and extremely diverse since there are many ways to “grow” parts. To understand the 3D printer landscape, start with the fundamental process types. Understand the six methods and then narrow the field.

Start at the 30,000-foot level to get a feel for the options that exist. Pick the best and then dig deeper. Begin with a good grasp of what your needs are; what is most important to you; and what applications will be the drivers. Define what success looks like in terms of product quality, time cost and operations. As you map out your processes, come back to Engineering.com for additional information and guidance.

Core Processes

The entire field of 3D printers is comprised of six core processes. They are presented (below) in alphabetical order. For each, highlights are presented, but note that these are generalizations that may not represent the characteristics of individual systems.

1. Extrusion

Stratasys Fortus 900mc

Fortus 900mc. Stratasys, Inc.

  • Examples:
    • Fused Deposition Modeling (FDM), Fused Filament Fabrication (FFF) and Plastic Jet Printing
  • How it works:
    • Heat and pressure combine to extrude a continuous bead of material.
  • Material class:
    • Thermoplastics; other non-metal, meltable materials
  • Advantages:
    • Functional, durable parts
    • Clean, safe and office friendly
    • Little/no facilities modification needed
    • Simple, straightforward and easy to use
    • Low entry price points
    Makerbot Replicator

    Replicator, MakerBot Industries.

  • Limitations:
    • Resolution
    • Surface finish
  • Price range: 
    • $500 to $300,000
  • When/why consider:
    • The primary driver is functional, durable parts for models, prototypes, manufacturing tools and production parts. 
    • Also consider that it is available as a self-serve, desktop machine or a centralized, corporate-wide solution.

2. Jetting

    3D Systems Projet 5000

    Projet 5000. 3D Systems Corp.

  • Examples:
    • PolyJet, Multi-Jet Modeling (MJM), Smooth Curvature Printing and Direct Metal Printing
  • How it works:
    • Mimics 2D inkjet printing. Tiny droplets of material are deposited through an inkjet-like head. 
    • Sub-types:
      • Deposit a binder on a powder bed
      • Deposit part material (e.g., photopolymer or wax)
    Solidscape D76+

    D76+. Solidscape, Inc..

  • Material classes:
    • Varied: 
      • When depositing binder — plastics, ceramics, sand, metal and more are possible
      • When depositing part material — photopolymer and/or wax are most common
  • Advantages:
    • Material variety
    • Process/vendor variety
    • Smooth surfaces and high resolution (material deposition systems)
    • Very large parts (binder deposition systems) — up to 13 ft
    • Low entry level price points
    Objet Connex500

    Connex500. Objet Inc.

  • Limitations:
    • Binder processes:
      • Secondary infiltration often needed
      • Can be messy
      • Surface smoothness and resolution
    • Material processes:
      • Approximation (at best) of commercial/production materials
      • High cost for waste (support material) for most processes
  • Price Range:
    • $15,000 to $750,000+
  • When/why consider:
    • Jetting has three primary niches:
      • Fast, low-cost models
      • High-resolution, smooth-surface objects
      • Large objects including molds and tooling
    • Due to the wide variety in this category, include (at least in your first pass) in all evaluations.

3. Lamination

    mCor Matrix

    Matrix 300. mCor Technologies.

  • Examples: 
    • Laminated Object Manufacturing (LOM – defunct), Ultrasonic Consolidation (UC)*
  • How it works:
    • Sheet stock is cut into 2D profiles and bonded to previous layers. Bonding is achieved with adhesives, in most cases, but may also include ultrasonic welding.
  • Material class:
    • Paper (previously, plastic and aluminum)
  • Advantages:
    • Low cost, readily available materials
    • Office friendly, no facility modifications
    • Simple, straightforward operations
    • Build time is not a function of size/volume
  • Limitations:
    • High scrap rate  (materials)
    • Fine details and thin walls aren’t recommended
    • Part extraction may be challenging
    • Stability (if uncoated)
  • Price range: 
    • $30,000+ *
  • When/why consider:
    • Models (concept/presentation) or bulky/thick-walled patterns
    • When a wood-like model is suitable
      • Currently, commercially available systems use paper. Prior attempts to use plastic/metal are no longer available for purchase.
    • *UC doesn’t fit the above characterizations. However, systems are no longer commercially available — focus is on research projects.

4. Melting

    Arcam A2

    A2. Arcam AB.

  • Examples:
    • Electron Beam Melting (EBM), Laser Cladding, Direct Metal Deposition, Laser Consolidation, Laser Engineered Net Shaping (LENS)
  • How it works:
    • Metal alloy is heated to a molten state
    • Sub-types:
      • E-beam or laser melts a bed of metal powder
      • Metal powder is melted and sprayed/deposited
  • Material class:
    • Metals — from copper to nickel-based superalloys
    Optomec Lens

    LENS 850-R. Optomec.

  • Advantages:
    • Metal parts that match/exceed properties of machined/cast parts
    • Gradient material properties (deposition systems) — blend alloys on the fly
      • Localized adjustment of material properties
      • Unique properties across entire part
    • Existing part repair (deposition systems)
  • Limitations:
    • Surface finish mimics as-cast parts
    • Secondary machining operations usually needed (e.g., machine shop required)
    • Experienced operators/machinists needed
    • Facility modifications required
  • Price range: 
    • $500,000 to $1,000,000+
  • When/why consider:
    • Ideal for prototypes, production parts and tooling components
    • Best used for low-volume applications where machining/tooling costs are high

5. Photo-curing

    envisionTEC Aureus

    Aureus.. envisionTEC.

  • Examples:
    • Stereolithography (SL), PolyJet, Multi-Jet Modeling (MJM), Digital Light Projection, Film Transfer Imaging (FTI) and Solid Ground Curing (defunct)
  • How it works:
    • Light sensitive materials are cured with UV or white light generated from lasers, lamps or LEDs
    • Several options combine jetting with photo-curing
  • Material class:
    • Photopolymers (plastics that solidify when exposed to light)
  • Advantages:
  • 3D Systems iPro 8000

    iPro 8000. 3D Systems Corp.

    • Good balance of speed, surface finish, resolution and overall part quality
      • Exceptional resolution available from several processes
    • Largest number of materials
    • Options include:
      • High speed processes
      • Fine detail processes
    • Wide range of part (envelope) sizes
      • From 64 in3 to 220 ft3
    • Low entry-level price options
  • Limitations:
    • One class of materials
      • Approximate (at best) production plastic properties
    • Property and accuracy stability over time
    • Secondary processes (curing) often needed
    • Experienced technicians suggested for some of the non-jetted process
    • Lab environment (HVAC control) needed for some of the non-jetted processes 
  • Price range: 
    • $15,000 to $750,000
  • When/why consider:
    • With so many options in this class, the only go/no go decision is if photopolymers are suitable for the application. Start with a review of the available material properties and proceed from there.
    • Used for everything from concept models, to functional prototypes, to patterns.
      • If considering production applications (non-pattern based), personal evaluation needed. Little data is available for long-term stability of material properties and overall part quality.

6. Sintering

    SLM Solutions SLM 280HL

    SLM 280 HL. SLM Solutions GmbH.

  • Examples:
    • Selective Laser Sintering (SLS), Laser Sintering (LS), Direct Metal Laser Sintering** (DMLS) and Selective Laser Melting** (SLM)
  • How it works:
    • Energy source (usually a laser) heats powdered materials to just below their melting point so that they fuse.
  • Material class:
    • Thermoplastics and thermoplastic elastomers
    • ** indicates metal alloys
  • Advantages
  • EOS EOSINT M 280

    EOSINT M 280. EOS GmbH.

    • Functional/durable parts
    • Filled/composite material options
    • Self-supporting parts
    • System capacity up to 200 ft3
  • Limitations:
    • Skilled operator highly recommended
    • Moderate resolution and surface finish
    • Tight operational controls suggested for consistent results
    • Low material reclamation rate
    • Facility modifications may be significant
  • When/why consider:
    • Functional prototypes or low-volume production
    • Industrial casting patterns (investment casting)
    • Due to training and facility overhead, not ideal for organizations with  low demand

**Processes actually melt metal powder – see melting section for details


As noted, this is a generalization of the characteristics of the six core processes. Help your fellow engineers by posting your comments to add the details and exceptions that you have discovered.

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