Small-batch production in MJF: where the prototype ends and the product begins

In product development, a prototype serves a clear purpose: engineers use it to verify part geometry, assembly correctness, and the basic functionality of the future product. Previously, such samples were rarely used in operation, with teams moving on after testing to preparations for serial manufacturing.

With the spread of industrial 3D printing however, the boundary between a prototype and a product has become less obvious. 

Multi Jet Fusion (MJF) makes it possible to print functional components from engineering materials and use them both for testing and in real devices. As a result, a customer can quickly move from a prototype to a pilot batch, and then to the release of a full-fledged product.

Definitions in practice: prototype vs product

In MJF projects, the boundary between a prototype and a product is defined by the part’s purpose, the requirements for its properties and repeatability, the level of design maturity, and the batch economics – volume, unit cost, and lead time.

When engineers create a prototype, they validate the design. Production repeatability metrics will include whether the part assembles with other components, that the mechanism operates correctly, and whether it withstands mechanical load testing. At this stage, requirements for service life, dimensional stability control control, and surface quality are usually lower.

A product is a component that already works in a real device having passed end-use validation. It must withstand operational loads, be consistently repeatable in every batch, and meet specified tolerances. 

If, following DfAM optimization (Design for Additive Manufacturing), this type of component can be produced in series without manual finishing and used immediately in equipment or a device, it’s already considered a product.

When an MJF part can already be considered a product

This is where MJF small batch manufacturing small batch manufacturing changes the familiar manufacturing logic. Thanks to process stability and engineering materials, when we now look at prototype vs production 3D printing, a component that was printed for testing often turns out to be suitable for operation as well.

During printing, the powder supports the part geometry, so complex shapes can be produced without support structures. MJF end use parts also show high dimensional repeatability, and their mechanical properties remain comparable in all directions. For example, finished parts made from HP PA 12 polyamide have the following properties:

Density of finished parts	1.01 g/cm3
Tensile strength, max load, XY	48 MPa
Tensile strength, max load, Z	48 MPa
Hardness (Shore D)	80
Elongation at break, XY	20%
Elongation at break, Z	15%

HP PA 12 polyamide properties

This makes it possible to produce batches of functional components  –  device housings, brackets, and various mechanical parts.

Limitations: where MJF remains prototyping

Despite the technology’s capabilities, there are tasks in industrial 3D printing for products where MJF is more often used for development. This includes parts with very tight tolerances – around ±0.02–0.05 mm, seating features for optical components (lenses, objectives, optical sensors), and sealed joints. Here, additional machining may be required after printing.

Limitations can also arise from operating conditions. If a part operates at extreme temperatures or requires special coatings, engineers may choose a different manufacturing technology. Special coatings are used when a part is expected to deliver not only strength, but also stable surface properties, such as improved water resistance, chemical resistance, and compliance with hygiene requirements.

In injection-moulded products, these tasks are often addressed through the material and a finishing layer: varnishes/coatings and impregnations are used for sealing, reducing porosity and surface water absorption; for food contact, polymers with confirmed food-contact compliance (e.g., under EU 10/2011 or FDA 21 CFR) are used, along with coatings that provide a smooth, easy-to-clean surface.

That’s why MJF is often used as an intermediate stage: first, the design and functionality are validated, and then a decision is made about scaling production.

Expert opinion

When a project moves from prototyping to a small-batch run, customers usually have similar questions. Most often, they arise at the stage of preparing the first series. Below are Makerly engineers’ answers to the most common queries.

What might customers overlook when placing an order, moving from prototype to product in MJF?

One of the most common issues regarding additive manufacturing production parts, is designing without considering the specifics of the technology. For example, the model includes gaps that are too small between elements, walls that are too thin, or undefined surface requirements. Sometimes post-processing is not planned either. As a result, the prototype works, but when the batch is repeated, problems with assembly or strength appear.

When does it make sense to print a model without changes, and when does it need to be adapted for MJF?

If a part is compact and does not include complex mechanical assemblies, it can often be printed without changes. However, large flat parts, snaps, moving joints, and threads usually require design adaptation.

A separate factor is part size. Industrial HP Jet Fusion printers have a build volume of 380 × 284 × 380 mm, so large parts are sometimes optimised or split into several pieces.

How do you choose a material in the “prototype–product” logic?

The material is selected based on operating conditions. For example, HP PA 12 polyamide is used for durable housings and mechanical parts. It withstands loads well, is moisture-resistant, and is suitable for dyeing. TPU is chosen for flexible and wear-resistant elements, such as seals or damping components.

Small-batch production as a bridge to volume

Small-batch production in MJF often becomes an intermediate stage between development and mass production. Typically, it involves batches from 10 to 1,000 parts.

Such batches make it possible to test the product in real conditions, gather user feedback, and refine the design. At the same time, there is no need to manufacture moulds, so an updated version of the product can be launched in the next batch.

Economics and time-to-market

The difference between additive manufacturing and traditional moulding is especially noticeable in launch timelines.

Manufacturing an injection mould typically takes 6–12 weeks, and its cost can reach tens of thousands of dollars. That means moulding only becomes economically justified at volumes of thousands or tens of thousands of parts.

With MJF low volume production, manufacturing can start immediately after the 3D model is prepared. The first batch of parts is often received within a week. This allows faster time-to-market and reduces risk at the development stage. For example, for one customer, Makerly specialists produced a small batch of identical products – gas detection units for indoor spaces – that fully met the necessary technical requirements. Printing took only 7 days.

In additive manufacturing, a product begins where the result becomes predictable and stable. If a part can be produced in batches, has passed tolerance verification, and works without manual finishing, it can already be considered a full-fledged product.With the implementation of a quality assurance workflow, MJF technology makes it possible to move from the first prototype to a functional series in just a few iterations. As a result, in many projects the transition from prototype to product occurs much earlier than in traditional manufacturing.