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3D-Printed Jigs and Fixtures: An Overlooked Way to Aid Manufacturing

BMW uses FDM to create fixtures and aids that are comfortable for workers to use, and promote repeatability and accuracy during product application. (Image source: Stratasys Direct 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, as has the associated impactful benefits.

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.
Effective jigs and fixtures help condense assembly and post-processing work into a controlled, repeatable process, leading to higher output and increased accuracy. 3D printing helps engineers achieve affordable rebuilds and design alterations for their fixtures. Whereas small design tweaks for jigs and fixtures built via traditional manufacturing would cause time and cost inefficiencies, 3D-printed parts can be quickly and inexpensively altered by simply updating a design file.

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.

Laser sintering conforms to organic shapes and is commonly used for guides on tubes and ducting. (Image source: Stratasys Direct Manufacturing

It's worth noting which 3D-printing technologies aren't viable for building manufacturing aids, to avoid spending time and resources where there's no potential.

Vat polymerization processes such as stereolithography are not well-suited for the job, as they use materials with low elongation and tensile strength, resulting in brittle parts. Because this technology cures materials with UV energy, parts are also more susceptible to degradation from light over time. Their resins also have low heat deflection, making them warp in in hot temperatures. Simply put, parts built via vat polymerization processes don't have the stamina or strength to handle the repeated use required of durable manufacturing aids.

Direct Metal Laser Sintering (DMLS) is a process which uses a precise, high-wattage laser to micro-weld powdered metals and alloys. While it's great for building dense metal parts used in aerospace and energy applications, it's not ideal for making jigs and fixtures as the post-processing labor can be intense and more expensive than FDM or LS.

Putting Knowledge into Practice

Understanding the main processes and materials to use is key to a successful project. Leading manufacturers in a number of industries have put their knowledge of 3D-printing manufacturing aids into practice, building reliable and durable jigs and fixtures for various applications. These aids have helped companies improve manufacturing and transform the production process.
A major German automaker used FDM with ABS thermoplastic to produce ergonomic handheld assembly devices and fixtures. They are up to 72% lighter than conventionally produced metal manufacturing aids. The weight reduction translates to a better experience for workers, who use the 3D-printed aids and tools hundreds of times a day.

BMW uses FDM to create fixtures and aids that are comfortable for workers to use, and promote repeatability and accuracy during product application. (Images source: Stratasys Direct Manufacturing)

In this case, the assembly and test fixtures are used for attaching bumper supports and fixture magnets. These aids incorporate tubes that bend and curve in a fashion that would be very difficult or costly to produce without additive manufacturing. FDM fixtures result in improved productivity, process repeatability, and worker comfort.

Just as it does for every series of vacuum cleaner a major vacuum cleaner manufacturer produces, the company makes 40 to 50 identical assembly pallets for its upright commercial vacuum. Each assembly fixture consists of four plastic posts that attach to a standard assembly pallet. To simplify production, the company used FDM to create the assembly pallets and ended up reducing production costs by 65%.

A European automaker realized time and cost savings by using FDM to create its manufacturing aids. The company slashed tool production costs by up to 90% and built its assembly tools within 24 hours. These tools are used for a number of applications, for example, precisely attaching different components such as roof spoilers and rocker moldings to the car, and helping to assemble a glass roof or retractable roof. 3D printing its assembly tools also meant the carmaker had freedom to create more customized tools adapted to the worker and the specific car.

Manufacturers are no longer overlooking the benefits 3D-printed jigs and fixtures offer. Having a thorough understanding of 3D printing's processes and materials better positions them to create customized jigs and fixtures that can streamline production processes and pad bottom lines. By using 3D printing to build manufacturing aids, companies can aid their manufacturing.

Bob Wolter leads Professional Services at Stratasys Direct Manufacturing, which offers on-site assessment and insight for businesses looking to incorporate 3D printing into their manufacturing processes. Bob joined Stratasys, Ltd. in 2012 and served as a Manufacturing Engineer, Tooling Engineer and Product Development Manager before launching Professional Services in 2015.

TAGS: Materials
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