Design for Subtractive Manufacturing

• Subtractive Manufacturing - AKA Machining - involves removing/subtracting material from a larger piece of material until you arrive at the desired shape/size of the final part

  • Because of the inherent nature of Subtractive Manufacturing, it is often less Sustainable than other manufacturing methods, as it typically produces a large amount of "wasted" raw material

  • Material can be removed a variety of ways, but all typically result in the removed material become devalued or valueless waste material, either in the form of Chips or Dross

    • Depending on the process & techniques used - as well as the design of the parts being made - the amount of waste material can be either minimal or extreme, relative to the part being made

    • It is important when considering what type(s) of Subtractive Manufacturing processes should be used to machine a part that you attempt to reduce this waste as much as possible (don't turn a log into a toothpick)

• For the most part, all solid objects can be machined in some way or another, but the practicality & "machinability" of the material varies by material type

  • The most-commonly machined materials in industry are types of Metals, Plastics, & Composites:

    • Commonly-machined Metals include alloys of: Aluminum, Brass, Cobalt, Copper, Nickel (Inconel), Steel, Stainless Steel (Inox), Titanium, etc.

    • Commonly-machined Plastics include: Acrylonitrile Butadiene Styrene (ABS), Acrylic, Delrin, Nylon, Polycarbonate (PC), etc.

    • Commonly-machined Composites include: Carbon Fiber, Fiberglass, "Sandwich" Panels, Wood, etc.

  • Less-commonly machined materials include Ceramics, Foams, Glass, and Stone/Rock

Design for Joined/Assembled Manufacturing

• Joined/Assembled Manufacturing involves combining two or more separate components into one single product

  • Methods of joining/assembling can be divided into 2 distinct categories:

    • Permanent Joining Processes, including Welding, Brazing, Soldering, Adhesive Bonding, & Riveting, among others

    • Temporary Joining Processes, including Bolting, Clamping, Snap-Fitting, & (Electro) Magnetic Attraction, among others

• General Design for Joining/Assembly constraints take into account:

  • Material (in)Compatibility

    • When designing products for joining or assembly, it is important to ensure that the materials used are chemically, thermally, mechanically, and environmentally compatible. Incompatibility can result in poor joint strength, corrosion, cracking, or even chemical reactions that can cause damage to the product or even be dangerous.

  • Accessibility, Clearance, & Tolerance

    • The design of the product should allow for easy access to the areas that need to be joined or assembled. For example, if a product is going to be assembled using a robot, the parts should be designed in a way that allows the robot to easily reach and manipulate them.

    • Adequate clearance is essential for proper alignment and positioning of the parts. This means that the design of the product should allow for adequate clearance between the parts that need to be joined or assembled. For example, if a product is going to be assembled using screws, the parts should be designed with enough clearance to allow for easy insertion of the screws.

    • Adequate tolerance is essential for proper fit and function of the parts. This means that the design of the product should allow for adequate tolerance between the parts that need to be joined or assembled. For example, if a product is going to be assembled using a press fit, the parts should be designed with enough tolerance to allow for easy press fit without causing excessive slop or binding.

Design for Additive Manufacturing

• • Additive Manufacturing (AM) - AKA 3D-Printing - is the opposite of subtractive manufacturing, and works by starting with nothing and building-up/adding material until the final form of part is reached

    • Because of the inherent nature of AM, it is often more Sustainable than other manufacturing methods, as it typically produces little/no waste

      • AM can be done with a wide variety of materials and methods, all of which carry their own constraints, pro's/con's, etc.

      • Depending on the process, the form of the raw material can come in either wire/filament, powder, liquid, or a combination thereof

    • AM at its core is fusion of materials (AKA welding), which can be accomplished a variety of ways, including: Resistive Heating/Melting, Chemical Reaction/Transformation, Laser Sintering/Melting, Plasma Melting, & Friction Melting, among other methods

    • Also, depending on the process, there may be additional post-processing steps in order to fully solidify/bond the materials to one another to create a uniform structure within the part

Design for Hybrid Manufacturing

• Hybrid Manufacturing - as the name implies - is a mix between Additive and Subtractive Manufacturing. Material is both added and removed throughout the process

  • Hybrid Manufacturing is fairly common practice on industrial, Additively-Manufactured parts, although it is not typically done as a seamless, combined process - an example being shown in the gif above

    • Oftentimes, the rough part geometry is produced using AM first, then the key/critical geometry is cleaned up with Subtractive methods

    • Alternatively, hybrid manufacturing can bounce back-and-forth between additive and subtractive operations to incorporate precise geometry internally on parts, for example

  • Hybrid Manufacturing tends to combine the "best of both worlds" between Additive and Subtractive Manufacturing, and can be an ideal combination of methods that result in a highly Sustainable product