Posted April 27, 2021

Implementing Subtractive Rapid Prototyping Using CNC Milling

CNC milling is used for subtractive rapid prototyping

New part designs come in every size and shape imaginable to serve their various purposes, but they all share the necessity for quick production. Predictably, this is often due to a race to market, but there are other reasons. In some circumstances, the lack of a critical part may hold up product development for the rest of the system. In other cases, repairing an already operational system may require a replacement part. No matter the reason, design engineers need their prototype parts built as quickly as possible, and they often turn to CNC machining to get the job done.

CNC milling is one type of subtractive manufacturing process that offers many benefits, such as reduced time and expense, for those needing prototype parts built quickly. CNC mills are distinct from lathes which typically only create round, conical, or cylindrical parts. This article will look at the benefits of subtractive rapid prototyping using CNC milling machines.

The Benefits of Subtractive Manufacturing Processes

Subtractive manufacturing methods fabricate parts by removing material from a raw block or rod of material. For a machine shop, this involves mills and lathes to cut, drill, or grind the material into a part with the desired size and shape. The mills and lathes receive their instructions from computer numeric control (CNC) code generated from the part’s CAD models.

Additive manufacturing is the other process used to fabricate parts, done with 3D printing equipment or injection molding. Both subtractive and additive manufacturing processes have their pluses and minuses. Here, we will highlight the two main benefits of subtractive manufacturing:

  • Product durability: Using an additive manufacturing process to build a part may not give it the same strength as a part machined from a solid block of material. In additive manufacturing, the component builds up in layers through 3D printing or a sintering process. On the other hand, subtractive manufacturing fabricates parts from a solid core of material, giving them greater strength. This strength is essential for components used in high-stress applications such as industrial machines or aerospace.
  • Time and expense: Additive manufacturing processes may take longer to complete and cost more than subtractive processes depending on size and quantity. 3D printing will build the part up by adding material in layers, while injection molding requires a pre-built mold. Therefore, injection molding includes a substantial initial investment of time and money. With the ability to be quickly set up and programmed, subtractive manufacturing with CNC equipment is fast and less expensive.

Next, we’ll look more into the specific advantages of using CNC milling machines to produce prototype parts.

The Advantages of Subtractive Rapid Prototyping Using CNC Machining

While both additive and subtractive manufacturing processes have their unique benefits, using CNC machining to rapidly prototype parts offers four distinct advantages:

  • Speed: During product development, designers will need to evaluate a part for its form, fit, and function at various points throughout the design cycle. Additive manufacturing processes can take time to set up and perfect, while a CNC milling machine can create a geometrically complex part within a couple of days. Additionally, a component can be machined out of softer materials even faster if a rapid prototype is required for a test fit only.
  • Accuracy: CNC machining is a precise manufacturing process that can hold extremely tight tolerances. Although these tolerances fluctuate depending on the materials used, subtractive manufacturing will deliver the precision needed for accurately testing a prototype part.
  • Repeatability: Subtractive manufacturing processes using CNC machines reproduce the same results repeatedly. Designers won’t have to worry about variances between parts as they can be replicated repeatedly within the exact tight tolerances.
  • Materials: While additive manufacturing is limited to pliable materials for 3D printing or injection molding, subtractive manufacturing can use a wide range of materials. These materials range from softer plastics to hardened steel, with many different types and variations between them.

These advantages come with any type of CNC machine, whether it be a mill, lathe, or a combination. With these different benefits and advantages, here is what you can expect for rapid prototyping services at your machine shop.

Rapid Prototyping at Your Local CNC Machine Shop

Using a local CNC machine shop’s services will usually yield the best results for a rapid prototype part built. These shops can offer the following:

  • Versatility: With the different material choices available in subtractive manufacturing, a CNC machine shop will build the part you need. Additionally, these shops will have other machines, such as CNC lathes, that they can use to create the part according to your specifications.
  • Quality: Advanced modern CNC machines are equipped with several sensors to keep their work within the tolerances you need. Local CNC machine shops will also have specific quality control measures to ensure that the final part conforms to your CAD model.
  • Scalability: With the repeatability of CNC equipment, you can quickly move from prototype to production at your local machine shop. With their precision, the production parts you have built will be an exact match for the prototype parts that you’ve already tested and evaluated.
  • Service: Due to their proximity, your local CNC machine shop is in a position to offer the highest level of personal service. Their sales representatives are usually trained engineers and are available to help resolve design questions. Simultaneously, the shop can give you a much faster turn-around time than what is available in machine shops overseas.

At Plethora, we understand the pressures you are under to produce a high-quality prototype quickly and efficiently, and we have many services that can help. Starting with our online part evaluation and ordering system, you can get feedback on your part’s manufacturability nearly instantaneously. From there, our sales representatives are available to answer your questions and help move your project through our manufacturing system. To get started, upload your design files to Quote My Part or call us at 415-726-2256.

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The Plethora Team

The Plethora team is your go-to CNC manufacturer for hardware done right the first time. We have the tools and experience needed to create high quality custom parts quickly and with precision, whether you need a prototype or production run.

Topics: Design, Manufacturing, finishing, Rapid prototyping, CNC machining, Quality, manufacturing trends, CNC milling