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3D Printing vs. Injection Molding

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3D Printing vs. Injection Molding

Manufacturing is a numbers game – produce the most parts possible at the lowest cost. Injection molding has traditionally held the advantage when it comes to producing high volumes of complex and durable parts. In recent years, new technology has pushed 3D printing to the forefront, challenging injection molding as a viable alternative for production runs.

3D Printing, also known as additive manufacturing, is no longer just for prototyping. Advances in material science and machine capability have opened the doors to new design possibilities, faster turn around, and far less cost.

3D Printing vs. Traditional Manufacturing Comparison

The break-even point of 3D printing and injection molding has become much closer making costs relatively even for comparable production runs. New technologies have taken additive manufacturing from being used only for prototyping into a viable alternative for low- to mid-volume production.

Projects requiring tens of thousands up to millions of parts will still be made with traditional manufacturing but can benefit greatly from additive manufacturing in the early stages of development. The additive technologies most commonly used for production of plastic parts include Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF). Direct Metal Laser Sintering (DMLS) is an additive technology used to print metal parts. These processes are ideal for prototyping and in some cases low volume production but can easily produce hundreds or thousands of parts. 

The Selective Thermoplastic Electrophotographic Process (STEP) puts additive manufacturing on nearly equal footing with injection molding in both cost and material selection. STEP is capable of printing plastic parts with the same materials used for injection molding. STEP is also capable of printing parts with different materials and different colors simultaneously. The STEP machine prints layers of ‘voxels’ or 3D pixels. Each voxel is 22-microns thick. Voxels of different colors and materials can be laid down at the same time. The design possibilities are nearly endless. Products can be customized in real time to match branding or customer preference. Previously, producing products made of two different materials was done with an injection molding process called overmolding. It is a complicated process that requires costly tooling, and a lengthy turnaround. STEP can print parts with two different materials in one pass. This also leads to built-in cost cutting measures where possible, simply by printing with a cheaper material on the inside of the product while using the desired, more expensive material on the outside.   

Additive Manufacturing Benefits

Consider the many benefits that go beyond simple part-price comparisons when comparing 3D printing vs. injection molding.

#1 // Choose from a Wide Range of Production-Grade Materials

Material development continues to be a high priority within the additive manufacturing community. See the chart below for an example material comparison.

#2 // Reduce Project Costs and Time-to-Market

Soft launching or beta testing can now be used as a guide to the design process with little impact on per-part cost. Additive manufacturing can help you avoid the expense of reworking, or even worse, completely scrapping an expensive mold.

Lead times for additive manufacturing can be measured in hours or days instead of weeks or months. 3D printing with production-grade materials will let you enter the market while tooling is still underway or while production ramps up.

#3 // Enable Greater Design Flexibility and Break Free from Traditional Manufacturing Constraints

Modifications, improvements, and customization to parts can be implemented at any time simply by editing the Computer Aided Design (CAD) file. Parts-on-demand is now a reality. Digital tooling is always available and accessible worldwide. Parts can be made anywhere there is a compatible machine. Customizing parts by changing colors or design features can be done in the middle of a production run.

Additive manufacturing represents true freedom of design. Parts are built from the ground up, layer-by-layer. This allows designers the opportunity to introduce complex geometries that would be impossible to complete with conventional machining. Traditional methods are limited by the reach and capability of the cutting tools. Drastic undercuts, internal structures, and thin-to-thick walls are all possible with 3D printing.

Arkema Rilsamid® PA12 for Injection Molding
PA12 for HPs Multi Jet Fusion (MJF)
Tensile Strength
43 MPa / 6240 psi
48 MPa / 6960 psi
Tensile Modulus
1440 MPa / 208 ksi
1800 MPa / 261 ksi
Elongation at Break
Charpy Impact, Notched
0.7 J/cm^2
0.95 J/cm^2
HDT @ 0.45 MPa
HDT @ 1.82 MPa
135 ºC
55 ºC
175 ºC
95 ºC

Direct Part Replacement with Additive Manufacturing

Additive technologies will continue to grow as a significant force in the manufacturing process as designers and engineers embrace the advantages and more materials become readily available. 3D printing can now be deployed over entire production runs, enhancing multiple stages of the product development process, from prototype to end-use parts. Direct Digital Manufacturing (DDM) is the use of additive manufacturing to fabricate the final product and/or parts used during production and assembly of finished goods. DDM allows companies to exit the traditional manufacturing paradigm and realize the true freedom of additive technologies. DDM can be used to create parts-on-demand, make instantaneous design changes, and provide digital tooling to manufacturing centers around the world.

Additive manufacturing also enables the practice of Direct Part Replacement. Parts originally made with traditional manufacturing methods can now be printed anytime and anywhere. Direct part replacement will shorten lead times and lower costs. It is common to opt for direct part replacement when only a few thousand parts are required or as a bridge-to-production solution while injection molding tooling is still underway or before production can be brought online.

Featured Part Example — Injection Molding vs. 3D Printing

Example // A

Example // A

Featured Part Example

(A) Accelerated Lead-Time // While the cost-per-part is close in this example, the critical requirement was getting parts in days, not weeks. Fathom recommends taking an additive manufacturing approach as a bridge-to-production solution or to avoid tooling and simply build parts as needed.

Quantity Required // 3,500
Additive Manufacturing Part Cost // $3.52 ea. (Lead-time of five days)
Injection Molding Part Cost // $3.60 ea. (Lead-time of 25-30 days, prototype tool)*
Break-Even Point // 3,740 Parts
Material Used and Weight // PA12 (4.6 g)
Part Dimensions // 25 mm × 23 mm × 25 mm

*Injection Molding with Amortized Tool Price

Additional Part Examples

(B) Limited Production Run // The manufacturing cost of this particular part is high because of a complex parting line and challenging features. Additive manufacturing is ideal when projects require a lower part volume. This will save customers on the expense of tooling and can produce parts in a matter of days instead of weeks.

(C) Beta-Testing // This part is small and easy to nest within the build envelope of a typical Multi Jet Fusion 3D printer. Additive manufacturing allows for less expensive product testing when design changes are likely to follow. The value in this example is speed and design agility.

Quantity Required // 1,500
Additive Manufacturing Part Cost // $8.18 ea. (Lead-time of six days)
Injection Molding Part Cost // $12.46 ea. (Lead-time of 30 days)*
Break-Even Point // 1,829 Parts
Material Used and Weight // Glass-Filled PA12 (14.2 g)
Part Dimensions // 111.83 mm × 15 mm × 109.24 mm
*Injection Molding with Amortized Tool Price

Quantity Required // 1,000
Additive Manufacturing Part Cost // $9.90 ea. (Lead-time of three days)
IM Part Cost // $8.68 ea. (Lead-time of 30 days)*
Break-Even Point // 815 Parts
Material Used and Weight // PA12 (14.8 g)
Part Dimensions // 68.64 mm × 69.88 mm × 50.65 mm
*Injection Molding with Amortized Tool Price

Design for Additive Manufacturing

The adoption of a Direct Digital Manufacturing (DDM) is leading to innovative product designs, shattering long-held manufacturing barriers, and making product development less risky and more efficient. The examples below demonstrate how to better leverage the advantages of taking a Design for Additive Manufacturing (DFAM) approach to production parts.

Additive manufacturing provides design freedom, new production possibilities, and fewer technical limitations. Considerations when designing for additive manufacturing extend beyond the minimum print requirements. A mindset focused on DFAM recognizes the variety of new possibilities when designing specifically for 3D printing. The experts at Fathom can help guide you and your team on DFAM best practices.

Featured Part Example

(D) Optimized Design // Additive manufacturing can produce complex designs that would be impossible to produce using traditional methods. Traditional processes come with strict design rules to ensure cost-effective and reliable manufacturability. In this example, the improved design cannot be made with injection molding. Learn more about how this part was made here.

Advantage // Performance Improvement and Weight Reduction
Quantity Required // 1,000
Additive Manufacturing Part Cost of Optimized Design // $15.89 ea (Lead-time of four days)
Injection Molding Part Cost of Original Design // $18.15 ea (Lead-time of 30 days)*
Break-Even Point // 1,249 Parts
Material Used & Weight // PA12 (27.4 g)
Part Dimensions // 62.8 mm x 53.8 mm x 63.7 mm
*Injection Molding with Amortized Tool Price

Additional Part Examples

(E) Function Assembly // Combining parts of an assembly into a single build is another advantage of additive manufacturing. This practice will reduce part count and cut assembly costs. In the following example, additive manufacturing is used to build one moveable assembly that would have traditionally required two tools and stock components. The value is production speed and no assembly required.

Advantage // No Assembly Required
Quantity Required // 1,000
Additive Manufacturing Part Cost // $12.83 ea. (Lead-time of three days)
Injection Molding Part Cost // $12.58 ea. (Lead-time of 35 days for prototype tool plus five days for production)*
Break-Even Point // 960 Parts
Material Used and Weight //  PA12 (32.9 g)
Part Dimensions // 64 mm × 19.35 mm × 60 mm
*Injection Molding with Amortized Tool Price

(F) Part Consolidation // Part consolidation not only reduces costs incurred (e.g. needing multiple tools), but it also reduces other costs, possibility of defects, human error, and stacked tolerances associated with assembly. In this example, additive manufacturing consolidates a three tool process down to one production run.

Advantage // Consolidation of a 5-Part Assembly
Quantity Required // 2,000
AM Part Cost // $24.69 ea. (Lead-time of eight days)
IM Part Cost // $28.72 ea. (Lead-time of 35 days for prototype tool plus five days for production)*
Break-Even Point // 2,150 Parts
Material Used & Weight // PA12 (68.5 g)
Part Dimensions // 140 mm × 25 mm × 140 mm
*Injection Molding with Amortized Tool Price

More and more products will become candidates for 3D printing as the technologies continue to mature and associated costs decrease. Additive manufacturing is an evolving landscape and every application or geometry will be different. An application that was not a good fit a year, six month, or even several weeks ago could now be an excellent candidate for additive manufacturing. Contact an additive manufacturing expert at Fathom to help you identify whether or not your project may benefit from any aspect of additive manufacturing.

What is Injection Molding?

Injection molding (or moulding) is a popular manufacturing process used to make plastic parts or assemblies. It is widely used due to its versatility and cost-effectiveness when producing vast quantities of the same item. Injection molding is used to make commercial, consumer, and industrial goods. This unique manufacturing process offers businesses the opportunity to create custom products with details that are specific to their brand.

The injection molding process begins with the machining of a metal mold. The mold will make up the majority of the cost associated with injection molding. The large upfront costs can then be spread out over the production life cycle. Most steel molds can produce hundred of thousands of parts. Molds can take weeks to complete depending on the design of the product. The mold is then placed in a specialized injection molding and manufacturing can begin. Plastic pellets are loaded into a hopper on the machine. The plastic then travels to a heating chamber where it is melted. The melted plastic is forced into the mold under pressure. After the plastic has cooled, the mold is opened and the part is ejected. The process is now ready to begin again. Injection molding machines are capable of producing vast quantities of parts.

When Should You Use Plastic Injection Molding vs. 3D Printing?

Injection Molding is Best For //

  • Higher Volume Production of 1,000+ Parts
  • Cost Reduction at Higher Volumes
  • Strict Material Requirements
  • Tight Tolerances
  • Consistency
  • End Use Parts
  • Different Sizes and Design Complexities

3D Printing is Best For //

  • Low-to-Medium Production Runs
  • Prototyping
  • Turnaround Time in Days or Weeks
  • Designs that Require Frequent Adjustments
  • Smaller Plastic or Metal Parts
  • Components of Varying Complexities
  • Bridge from Prototyping to Production

3D printing and injection molding should be viewed as complementary manufacturing methods. A project may use a 3D printing process to create a rapid prototype and begin low-volume production, but then switch to injection molding once there is a greater demand for a part. 3D printing can also be used as a bridge to production, allowing the customer to speed products to market while full-scale production is ramping up. 3D printing has the capability of producing parts on demand but cannot match the volume possibilities of injection molding. Fathom’s network of manufacturing resources includes the international production capacity of ICOMold by Fathom. Domestic production and international purchasing allows for quick turnaround times on small to large orders.  

Most 3D printed parts will need some type of post-processing to eliminate the raw feel of the printed material. AMT PostPro3D technology is a high-quality option to consider for smoothing 3D printed parts. The AMT PostPro3D achieves a high quality surface finish that matches injection molding techniques using 3D printing processes. This is a smart and automated solution for smoothing 3D printed parts. PostPro3D reduces lead-time, cost of manufacturing, and operational and maintenance costs while providing the ‘missing piece’ in the digital manufacturing chain. The PostPro3D machine makes 3D parts cost competitive for high volume production. 

Talk to an expert at Fathom today to take your parts to the next level using AMT PostPro3D for post processing. 

Get an instant 3D printing quote and a traditional manufacturing quote in as soon as one hour. 

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