Design Knowledge Intermediary
3D-Printed Jigs and Fixtures: An Overlooked Way to Aid Manufacturing
With the manufacturing industry continually abuzz about 3D-printed cars, airplane wings, and biomedical devices, the role jigs and fixtures play in 3D printing has often been overlooked. The truth is, though, that 3D printing these manufacturing aids, whether simple assistors like rulers or complex holding fixtures, yields understated yet impactful benefits.
To take advantage of benefits such as decreased labor costs, part consolidation, and increased productivity, industry professionals need a greater understanding of which 3D-printing process and materials make sense for their projects. Let's look at how engineers can successfully use 3D printing to streamline production -- and help their companies' bottom lines -- for their next jigs and fixtures project.
Defining Jigs and Fixtures
Fixtures are manufacturing aids used primarily during assembly or product testing. They can incorporate any number of features that designate locations for drilling, alignment, artwork placement, and other mechanisms. Commonly used fixtures include:
• Assembly line fixtures: Can be anything integrated into an assembly line, including pick-and-place fixtures for quickly putting components together for a final product, or more complicated alignments used for gluing or threading screws.
• Calibration fixtures: Regulate the position and depth of a feature.
• Drill fixtures: Hold parts in place and support designs during drilling. Locking parts in place eliminates movement and allows for the creation of evenly spaced holes.
• Holding fixtures: Commonly used during transportation and storage.
• Shim fixtures: Align part components for even assemblies.
• Test fixtures: Incorporate precision testing devices on a single platform that can improve the functional performance of a certain assembly or entire part.
Choosing the Right Process and Material
Not all 3D-printing processes or materials are suited for building jigs and fixtures, so it's important to understand what technology and corresponding material can best bring a design to life. Two common processes used for creating manufacturing aids are Fused Deposition Modeling (FDM) and laser sintering (LS).
FDM's building process resembles a hot glue gun in that it extrudes heated filament. For added design freedom parts can be built with water-soluble support material. LS, on the other hand, melts designs in a bed of powdered material that allows for intricate, interweaving, no-access features. Both technologies use production-grade plastics with heat/smoke/toxicity ratings, chemical resistance, and Federal Aviation Regulations (FAR) 85.853 ratings. These materials also have a history of performance in transportation, aerospace, and other high-impact fields.
Popular FDM materials include:
• ABS M30: Stronger than standard FDM ABS filament with a variety of color options.
• ASA: UV-stable material with great aesthetics and strength similar to ABS.
• PC: A durable, strong material used in automotive, aerospace, and medical applications.
• PC-ABS: One of the most widely-used industrial thermoplastics. It combines the most desirable properties of both ABS and PC.
• ULTEM 1010: Excellent strength and thermal stability as well as steam autoclaving.
• ULTEM 9085: High strength-to-weight ratio; UL94 V-0 rated.
Popular LS materials include:
• Carbon fiber-filled nylons: Electrostatically dissipative, high strength-to-weight ratio.
• Glass-filled nylons: Dimensionally stable with excellent stiffness and elevated temperature resistance.
• Mineral fiber-filled nylons: Stiff, non-conductive, and typically RF-transparent.
• Nylon 11: High elongation with superior chemical resistance.
• Nylon 12: Rugged, general-purpose nylon with good mechanical performance and chemical resistance.
Both of these primary processes excel at building different types of jigs and fixtures. Because LS builds in a chamber just below the plastic's melting point, making its parts more susceptible to warping, FDM is better for creating manufacturing aids with large, flat surfaces. On the other hand, LS can create support-free builds, making it more suitable for parts requiring organic and curving shapes, like fixtures, ducts and pipes.