With many manufacturing companies constantly working to improve productivity and lower costs, lean manufacturing techniques such as the implementation of grippers, jigs, fixtures and manufacturing aids in a production line help achieve these goals. The high level of customization and complexity that AM allows for in a design coupled with the speed and accuracy that parts can be made, make it an ideal solution for producing grippers, jigs, fixtures and manufacturing aids.
Grippers, jigs, fixtures, and manufacturing aids are used in manufacturing to ensure that component parts can be produced accurately over many cycles or iterations. The jig supports and holds a workpiece in place while guiding a machining or cutting tool as it carries out a specific task. The fixtures and grippers provide additional support and precise location for each part.
Jigs and fixtures are typically made from steel or aluminium, but the introduction of 3D printing or more accurately additive manufacturing means a greater range of materials can be used. This process has been adopted most prominently in the automotive, defense, aerospace, and rail industries. Jigs and fixtures can be off-the-shelf, but often manufacturers will custom design their own manufacturing aids for unique operations to their products. Additive manufacturing (AM) eliminates the cost, lead time, and design barriers to adopt manufacturing aids on the shop floor. AM can deploy jigs and fixtures where they previously could not exist due to several key advantages.
Source: Jabil
Image: Production Enablers can get the most benefits when manufactured with AM
What are grippers, jigs, and fixtures?
Gripers, jigs, and fixtures are workpieces used to aid in the machining, positioning, and assembly of parts in many facets of manufacturing. Grips, jigs, and fixtures can be made from a range of materials (typically steel or aluminium) and are CNC machined to high tolerance to allow a part to accurately locate into the desired position. Jigs and fixtures can also include attachments that allow the part to be secured in place. The high level of customization and accuracy required for grips, jigs, and fixtures usually result in long production lead times.
Grippers: The part of an automation process that is in contact with the workpiece is typically used to transfer or orientate the part. These are often custom-designed to match the geometry of a part.
Jigs: Holds the workpiece in place and also guides the cutting tool (e.g. a drill jig used for a guiding drill bit into the correct spot). Jigs are typically not attached to the machine and can be easily manipulated to align with the cutting tool. The accuracy of a part does not depend on the operator.
Fixtures: Locates, holds, and supports the workpiece securely as machining or assembly takes place (a vice is a simple fixture). Machining fixtures are generally secured to the machine to withstand the large machining forces the part is subjected to. The accuracy of the part still depends on the operator or assembler.
Dixon Valve EOAT Printed in Onyx material, Source: Markforged
Benefits of using 3D printing
Cost
The main benefit of 3D printed is the reduction in cost. The majority of savings come from the reduction in high machining costs. Typically a grip or fixture would be sent away to be machined by a highly skilled operator on a CNC machine over a number of days. With 3D printing, once the design of a 3D model is complete the file is sent electronically to the nearest printer, quickly analyzed, and printed on a machine that requires very little human interference. Grips and jigs made via 3D printing are also produced with much cheaper materials compared to traditional grips and fixtures further reducing the cost.
Speed
The other main benefit of 3D printed grips and fixtures is the speed at which they can be produced. Machining of complex metal geometries takes significant planning and highly skilled CAM designers and machine operations. This can result in the lead time for CNC machining taking days or even weeks before a part is completed. By using 3D printing to replace an aluminium assembly tool (see image below), a well-known car manufacturer was able to cut lead time by 92% from 18 days to 1.5 days.
Materials
3D printing offers a vast range of materials over a range of technologies. Engineering material properties such as chemical resistance, flame retardancy, heat resistance, and UV stability are now widely available in the 3D printing industry. Parts can be produced or finished in many colors and surface finishes. The polymeric materials used in 3D printing also mean that damage to parts (that come in contact with the grip or fixture) is limited during handling and assembly when compared to more traditional metal fixtures.
Weight
Grips and fixtures are regularly manipulated by workers. The majority of the materials used in 3D printing are lighter than aluminium reducing the load on workers and improving safety. Industrial FDM parts are not printed solid but rather filled with infill further reducing the weight of parts.
Design iterations
The speed that 3D printing can produce parts gives designers much more freedom to optimize a design through several iterations. 3D printing technologies also allow for complex and ergonomic designs to easily be produced improving worker interaction and comfort.
High accuracy
Several 3D printing technologies are able to produce a high level of accuracy (Industrial FDM - ±0.2 mm, SLA - ±0.05 mm, HP MJF, and SLS - ±0.1 mm). SLA and HP MJF can also produce fine and intricate details as well as functional connections like snap fits and interlocking features.
CMM Fixture, Source: Javelin Technologies
Common applications and solutions
3D Printed workholding using Markforged Composite 3D Printer
Benchtop assembly jig
· High level of customization to suit part geometries
· Simple to secure to a bench
· Ergonomic design
· Integrated electronics
· Wear-resistant material that will not damage parts
Industrial FDM allows for a large build size and uses a range of engineering materials (including nylon and PEEK). Very cost-effective compared to traditional manufacturing methods and one of the faster methods of 3D printing.
Automated robotic arm grip
· High accuracy to match part geometry exactly
· Chemical and wear-resistant material
· Simple interchangeability and replacement
HP MJF produces wear and chemical resistant parts at high accuracy (± 0.1 mm) from fused nylon with no need for support and very few design constraints.
Hand-held assembly device
· Lightweight and stiff material
· Ergonomic design with complex organic shapes
· Threaded inserts or holes for attaching brackets
· Accurate part placement
Industrial FDM is able to produce large, lightweight parts. The ability to produce threaded holes means parts can be assembled together.
Coordinate measuring machine (CMM) inspection fixture
· Rigid connections to part for accurate positioning during the measurement
· Quick construction to allow accurate prototype testing
· High level of customization
· Rapid design iterations to match design changes
· No contact marking or scratching
SLA components are produced with a photopolymer resin and allow for a high level of detail and accuracy (± 0.05 mm). There is a range of engineering resins available with properties to suit all applications. While SLA builds volume is typically much smaller than industrial FDM. HP MJF and SLA parts are can be printed as attachments to larger universal connections.
Clearance gauge
· High accuracy
· Chemical and wear-resistant material
· Easy to maintain and replace
SLA is perfect for fine details where clearance and fit are important.
Custom part-specific storage
· Low accuracy needed
· High level of customization
· Easy tool removal and placement
· Large size
· Colour coding
Industrial FDM provides a large build envelope and provides good dimensional accuracy (± 0.2 mm). It is easy to design and print with and comes in a range of colors for easy tool identification.
Advantages adopting AM for Factory Floor Production Enablers
1. Cost Reduction
Time is money, and the reduction in time taken to produce parts by additive manufacturing rather than machining automatically saves you money. In addition, instead of outsourcing the machining of specialized jigs and fixtures, they can be printed in-house. This saves both time and money paid to third-party suppliers.
With additive manufacturing, a 3D model is designed on a computer and sent electronically to your 3D printer. There, it's immediately analyzed and printed automatically, requiring very little time or labor. Jigs and fixtures made in this way also use much cheaper materials, such as thermoplastics.
2. No Machining
3D printed jigs and fixtures can be produced very quickly, because of the way they’re designed and the materials used in additive manufacturing. To have such parts CNC machined frequently involves sending them out to a specialist in complex metal geometries. You need highly skilled CAM designers and a significant amount of planning, which extends lead times into days, and sometimes weeks. Additive manufacturing and design can largely be done in-house, cutting lead times down to a day or less.
3. Customization
Another reason why you should use 3D printing for jigs and fixtures is that you can design them to fit your own particular needs and circumstances. You can deploy much more complex geometries, and produce tools that would not be possible using traditional machining methods. You can also make your parts in a range of colors and surface finishes. Your engineers no longer need to design a tool purely for its manufacturability; they now have the ability to tailor the tool for the task or the operator.
3D printing takes advantage of a wide range of technologies and materials, and you can build in special properties such as heat and chemical resistance, UV stability, and flame retardancy. This enables the design of strong, lightweight tools with high-performance materials, for complex and precise operations such as medical surgery.
Most of the materials used for additive manufacturing are lighter than aluminium, and are not printed as a solid but rather as a shell that is completed with infill. This further reduces the overall weight of parts and consequently helps to increase productivity. Tools are less cumbersome and easier to move around the production floor. Materials like thermoplastics, rubber, and silicon can also be combined in 3D printing to create new materials with significantly greater mechanical properties. These can then be used to make stronger, lighter tooling parts.
4. Component Consolidation
One of the most compelling reasons why you should use 3D printing is the freedom of design that additive manufacturing allows. Tools can be much more complex, but you can also reduce or even eliminate altogether the long lead times, labor, and costs that are required for assembly operations. Instead of multiple components being engineered for a tool requiring assembly and fitting, the whole thing can be redesigned as a single contiguous component. This will improve the overall precision and accuracy of the finished tool while allowing no opportunity for failure of contributory parts.
5. Faster Iterations
Since 3D printing is based on 3D CAD models and a digital manufacturing process, you can do as many iterations as you like in a much faster time. Once you're satisfied with the CAD model, all you have to do is upload it to your 3D printer, and you could potentially get your part printed in a few hours. It takes so little time that, if you don't like the design or it has a flaw, you can keep optimizing it through as many iterations as it needs to get it right.
The rapidity of these processes means that your designers have a great deal more freedom and time to optimize their design before it goes into full production. This may have a substantial impact on your ability to deliver products to your customers speedily on demand, thus improving your company standing.
6. Complex Design
3D printing makes it much simpler for you to come up with new and improved designs that will help your jigs and fixtures to deliver a better performance. To do this with tools produced by traditional methods would be a colossal task, requiring much more effort and expense to create new jigs and fixtures. With 3D printing, you can create new designs at regular intervals, optimized for performance, and delivered with greater speed and less cost.
As your tool production will no longer be limited by machining or injection molding operations, you have a much larger scope with 3D printing for tool configuration. This means you no longer have to worry about conventional design considerations, such as irregular contours or profiles, or the number of setups that will be required for your parts.
7. Digital Inventory
In a manufacturing context, digital inventory refers to a computerized file management system that provides you with virtual storage for your 3D designs. Storing parts virtually means that you can reduce your warehouse space, as you'll no longer need to maintain a significant physical inventory. You'll have instant access to your CAD models and design files, making your production abilities more immediate and agile. Another very compelling reason to use 3D printing for your jigs and fixtures is that you don't have to have a big production run. In fact, it's better suited to producing lower quantities on demand.
A further advantage is that you can replace obsolete components, by redesigning them for 3D printing and digital storage. Retrieving files when needed is fast and simple, with no heavy lifting required. Parts can even be produced in the location where they're actually going to be used, which has a great impact on logistics.
Once you install a 3D printer and digital inventory on your production floor, you'll be able to produce parts in-house, and no longer need to move them around physically. This will not only speed up delivery but also reduce your shipping volumes and transportation costs. This is particularly useful for any business that operates in extreme or remote locations, such as battlefields, oil rigs – or space stations!
8. Better Ergonomics
Jigs and fixtures have to be physically handled by people on the production floor, so reducing their weight using 3D printing can make them easier for workers to use. Designing tools with CAD modeling also means that you can incorporate organic shapes and contours, providing operators with greater comfort and improved accuracy. Jigs and fixtures with ergonomic functionality help to reduce both downtime and the number of flawed units, and are safer for operator health.
References: Hubs
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