3D Printed Manufacturing Aids: Jigs & Fixtures

In a webinar on the subject, Alissa Wild, senior business development manager at Stratasys, a 3D printer manufacturer, offered descriptions:

Jigs are custom-made tools used to guide and control the location and motion of a workpiece during an operation. An example of a jig is a drill guide. The purpose is to provide repeatability and accuracy, as well as to maximize efficiency of manufacture.

Fixtures are devices used to locate and hold a workpiece in a fixed location during a machining operation or other industrial process. Examples of fixtures are chucks and vises. The purpose is to maintain consistent quality and reduce the cost of production. Since their functions are similar, the terms jig and fixture are often used interchangeably. In most cases this article uses fixture to indicate both.

AIDS TO MANUFACTURING

For many fixturing applications, simple off-the-shelf devices do the job of holding parts or assemblies in the correct position, Wild said, including various clamps, vises, chucks and collets. Special-purpose, custom-designed fixtures are made to hold a particular workpiece for a specific operation.

When conventionally built, these fixtures are made from metal, wood or plastic and have to be custom machined or fabricated and hand assembled. They can be intricate in design and are usually expensive and time-consuming to make. In every situation where a fixture might be used, plant staff have to decide whether it is worth the expense and delay.

3D printing allows complex fixtures to be fabricated quickly, without machining or other expensive processes. Where a simple cradle-type fixture might cost thousands of dollars and take four to six weeks to produce, Wild said, a 3D-printed version might cost less than $100 and take only days to produce.

In some applications, such as fixtures for welding or holding heavy parts, high-strength or high-temperature material may be necessary. Another alternative would be a hybrid fixtures combining conventionally built parts with 3D-printed parts. For example, a welded frame might support 3D-printed forms.

In addition to streamlining and enhancing manufacturing processes such as machining, custom 3D-printed jigs and fixtures can provide value in assembly and quality control.

EFFICIENT PROCESSING

3D-printed fixturing can improve work holding on machine tools and other processing equipment. Does an odd-shaped part need a secondary operation? Or 3D-printed custom jaws to hold it? Would it help to have a robot load/unload an unwieldy part in a machining center? 3D printing can produce grippers to fit the part.

FASTER AND MORE ACCURATE ASSEMBLY

Something as simple as a holder for an assembly can take minutes off assembly time. If the assembly is securely held in the most convenient position, the person adding parts has the best access to it, as well as having both hands free to do the job.

Simple 3D-printed alignment tools can also reduce cycle time, while preventing error and operator fatigue. In some processes where alignment and clearances are important, fixtures are necessary for preventing misalignment. In this case, 3D-printed fixtures do the same job (and maybe more) for many fewer dollars.

CONSISTENT QC

HOW TO GET STARTED WITH 3D PRINTING

Since this is such a different way of building things, it takes a while to discover ways to use it. A company can get started with 3D printing without investing in the machinery. As a first step try out the concept by having a fixture made at a nearby 3D printing or rapid prototyping shop. The staff there is accustomed to working with those new to the concept and can take a sketch or a CAD drawing and turn it into a real part, usually in a matter of days.

Consider problem areas that a specialized fixture might help. For this first project, choose a fixture that will function well when made in one of the standard plastic 3D print materials. The application shouldn’t require much strength or heat resistance.

Later on, as plant staff encounter more and more applications for 3D jigs and fixtures, investigate purchasing a 3D printer. A wide variety are available; choose one that meets the application’s requirements for material selection, precision and other factors. Basic units that build parts in ABS or PLA plastic may cost less than $2000. From there, cost depends on the build material, size and capability desired. High-performance materials include reinforced plastics and metals.

Like any new process, 3D printing has its own learning curve. Some staff will need training, often available free with purchase of the equipment. Expenses in addition to the hardware include maintenance, the 3D build material and any additional chemicals, and perhaps specialized software.

Many companies find that once they have 3D printing available they discover more and more ways to use it to streamline their processes, improve quality, protect parts from damage and make other improvements. As with any new technology, it will take time and maybe some trial and error to understand the capabilities of and applications for 3D printing in the factory or on the job site. The possibilities are endless and likely well worth the effort.

Barbara Donohue is web editor for VALVEmagazine.com.