Subtractive Manufacturing : Answering Some FAQs





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Simply put… Additive manufacturing adds material, and subtractive manufacturing takes it away. Both are used for prototyping and are practical for large-scale production. These processes have different fundamentals but are beneficial in conjunction with one another.

If you have questions about subtractive manufacturing options, consider Glenn Metalcraft Inc for guidance. We are experts in robotic welding, punching, automated machining, and waterjet cutting. Our engineers are available to support you through product manufacturing.

Today, we’re going to answer some FAQs about subtractive manufacturing.

What Is Subtractive Manufacturing?

A good analogy for subtractive manufacturing is a sculptor making a statue. Sculptors start with a big block of stone or wood and gradually chisel away at it. Eventually, they have a finished sculpture.


Subtractive manufacturing is an umbrella term for machining and material removal processes. The process starts with solid blocks, bars, rods of plastic, metal, or other materials.

The “subtraction” takes shape by removing material through cutting, boring, drilling, and grinding. It involves cutting, hollowing, or taking parts out of a block or sheet of a material, such as a metal.

Subtractive manufacturing is performed manually or by computer numerical control (CNC).

With CNC versions of subtractive manufacturing, a virtual model designed in CAD software serves as input for the tool. Software plans are combined with user input to generate paths to guide the cutting tool through the part geometry.

These plans tell the machine how to make necessary cuts, channels, holes, and any other features that require material removal. They take into account the speed of the cutting tool and the material’s feed rate. CNC manufacturing tools produce parts based on this computer-aided manufacturing (CAM) data, with little or no human assistance or interaction.

Subtractive manufacturing creates 3D objects by successively cutting small pieces of material away from a solid block of material.

Subtractive manufacturing helps create metal parts for prototyping, manufacturing tooling, and end-use parts. These processes are ideal for applications that require tight tolerances and geometries that are difficult to mold, cast or produce with traditional manufacturing methods.

Subtractive manufacturing offers a wide variety of material and processing methods. Softer materials are, of course, much easier to cut to their desired shape but will wear out more quickly.

What Are The “Pros” Of Subtractive Manufacturing?

CNC machining can produce more substantial parts with better tolerance and smoother finishes than additive manufacturing techniques. This is especially true of intricate features such as threaded holes. Additionally, extremely durable metal parts are produced using CNC machining.


What Are The “Cons” Of Subtractive Manufacturing?

CNC machining can require substantial set-up time. For this reason, subtractive manufacturing may be too expensive for anything but high quantities of parts.

What Is The Difference Between Additive & Subtractive Manufacturing?

Since we defined subtractive manufacturing above, let’s look quickly at additive manufacturing before comparing the two.

Additive manufacturing is synonymous with 3D printing or any process by which 3D objects; built by adding material, layer by layer. Modern 3D printing has always been beneficial for rapid prototype development, but it is starting to impact the manufacturing world.

So with additive manufacturing processes, adding material, layer by layer, and subtractive manufacturing conversely removes material to create parts. While these approaches are fundamentally different, subtractive and additive manufacturing processes are often used side-by-side due to their overlapping range of applications.

Is It Always A Choice – Subtractive vs. Additive Manufacturing?

While there are fundamental differences, subtractive and additive manufacturing are not mutually exclusive. The two are often used side-by-side or at different product development stages in manufacturing.

For example, the prototyping process often utilizes both additive and subtractive techniques.

Additive technologies are typically better suited for small pieces and highly intricate or complex designs.

In later stages of the development process, when larger batches are required, subtractive processes become more competitive.

Larger, less complicated manufacturing pieces lend themselves to subtractive manufacturing. Due to the myriad of choices in surface finishes and the speed of the process, subtractive manufacturing is often the choice for fabricating finished parts. As metal 3D printed components can be cost-prohibitive, subtractive processes are a better choice for metal parts for all but the most intricate creations.

In today’s manufacturing world, subtractive and additive processes often complement each other in tooling, jigs, fixtures, brackets, molds, and patterns. Manufacturers often opt for subtractive metal processes for higher volumes or pieces subject to more extreme mechanical strain and stress.

It is utilizing additive and subtractive manufacturing in tandem in a hybrid approach that is key. The process allows product designers and today’s manufacturers to combine the versatility and quick turnaround times of additive manufacturing with the strength of subtractively-produced parts.


What Are Some Subtractive Manufacturing Techniques?

  • CNC machining. This broad term refers to turning, drilling, boring, milling, reaming. It’s ideal for hard thermoplastics, thermoset plastics, soft metals, and hard metals (industrial machines).
  • Electrical discharge machining (EDM). This subtractive manufacturing process is ideal for hard metals.
  • Laser cutting. Laser cutting is ideal for thermoplastics, wood, acrylic, fabrics, and metal (like industrial machines).
  • Waterjet cutting. With or without abrasives, waterjets can cut almost any materials, including plastics, hard and soft metals, stone, glass, composites, and even food!

What Are Your Takeaways About Subtractive Manufacturing?

Here are the key points our FAQs went over. Subtractive manufacturing:

  • Removes materials from an object.
  • Can be done manually or by a CNC machine (computer numerical control).
  • Uses computers to aid machine processes, such as drilling or milling.
  • Is ideal for bigger parts and metal parts.
  • Can be a relatively fast set-up process.

GMI crafts the highest quality parts that others say are too complicated or too difficult. Our expert craftsmen and their equipment work within tight timelines and tolerances to meet customers’ specifications. We handle robotic welding, punching, automated machining, and waterjet cutting. Contact us for information about our subtractive manufacturing options.

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