With the increasing acceptance and use of 3D printing in many industries the use of 3D printing to make one-off small production number parts has grown. Many of these one-off parts are jigs and fixtures that aid in the production of other parts. They often improve the efficiency of assembly lines by performing unique and specialized tasks. These manufacturing aids vary dramatically in their complexity and use. A fixture can be as simple as a small tool to assist an assembly line worker place badges on cars, or as complicated as a robotic fixture with internal passages for pneumatics and electronics.
Jigs and fixtures are not a new aspect of the manufacturing industry. Manufacturing aids are an important aspect of a factory being able to produce goods with a level of accuracy and consistency. A simple fixture frame used to hold a part while drilling will assure that every part in the fixture frame will have a consistent hole location and produce an identical part for the rest of the assembly line to use.
Figure 1: Animation of CAD render and printed fixture
Jigs and fixtures have been primarily manufactured up to this point with traditional manufacturing techniques. Most of the time custom fixtures are machined out of aluminum or a block of plastic. Machining takes a significant amount of time and skill to produce parts. The more complex the geometry is the more time this process takes to machine a functioning part. It can take multiple weeks for a single part to be designed, machined, and shipped to the factory assembly line. If there are any design changes required the entire process starts over, resulting in an even larger amount of time lost with each iteration. The massive reduction in time is by far the most appealing aspect of additive manufacturing. Instead of fixtures taking weeks to produce, engineers can rely on additive manufacturing to produce parts within hours. A fixture can be designed, 3D printed, and if changes are required they can often be completed within the same day of part production.
The use of additive manufacturing to replace traditional jigs and fixtures allows a company the ability to maintain a digital inventory of its parts. With very short notice a failed part can be 3D printed in a matter of hours and replaced with minimal downtime. These parts are available on-demand, and with the use of SmartSlice™, these parts are printed with optimized print settings that speed up the print times while also assuring the part has the strength and stiffness required to perform as intended.
SmartSlice™ provides the tools to validate and optimize parts to improve part performance and print times. A user can experiment with different load cases that mimic the loads the jigs and fixtures would experience during use. The user can virtually experiment with many different materials and choose the right material for the application. For example, if a part needs to be more rigid a carbon fiber-filled material can be compared to a standard material. All of this "virtual experimentation" can be done before the first part is even printed in the SmartSlice™ software.
To better understand how additive manufacturing is used for jigs and fixtures, consider the following example fixture part in Figure 2. The part shown is a simple fixture used to firmly hold a 1 inch by 1 inch piece of aluminum. It is integrated with an off-the-shelf clamp that is bolted to the part to simplify the design and ease of manufacturing. This fixture could be seen on an assembly line where a worker needs to firmly hold a part for a short amount of time, and then release the part to move onto the next assembly process.
Figure 2: Side image of completed fixture
The video below is a quick look into the setup of this fixture in SmartSlice™. For any simulation, the setup is one of the most important aspects, and with the SmartSlice™ surface selection tools, users are able to apply the real-world forces to these parts virtually.
Figure 3: Fixture setup video in SmartSlice™
The first step after finishing the part setup is the validation process. SmartSlice™ uses the current user-defined printer settings to check if the part will meet the key requirements and make recommendations on further optimization. The validation process of this fixture takes under a minute and SmartSlice™ tells the user whether the part is going to perform as intended under the specific loading. This is a very powerful check, and often eliminates many of the first print break cycles a part might go through in testing. The validation step will tell you if the part is overdesigned, underdesigned, or simply will not work even when printed at 100% infill.
After the user has completed the validation they can manually make changes to the print settings, or they can use the SmartSlice™ optimization tool. SmartSlice™ optimization will manipulate the print settings and apply modifier meshes to high-stress areas of the part to provide the user with a part that fulfills the user-selected requirements but is also optimized for print time and material usage. The analysis generates 10 ranked solutions allowing the user to pick the most appropriate solution for their needs.
For this fixture example, it was found during the validation step that the part would not hold up to our clamping force when printed from a standard ABS material at 100% infill. SmartSlice™ showed the clamped down aluminum material would likely cause a crack to form along the inside edge of the fixture forming a low factor of safety in the areas shown in Figure 4 below.
Figure 4: SmartSlice™ validation results
The message produced from the SmartSlice™ validation provides the user with two options to improve the part to meet the requested requirements for this fixture. The first option is to try a stronger material, while the second option is to change the part geometry to improve the areas shaded in red. In this case, a fiber-filled nylon material was chosen to replace the ABS for its excellent strength properties and printability. With the fiber-filled nylon material, SmartSlice™ was able to validate the material would hold up to the specified loads and could be optimized to further improve our part’s performance. The table below shows the computed results of the ABS validation study on the left, and the results of the optimized fiber-filled nylon on the right.
ABS Validation Results
CF Nylon Optimization Results
The results above are from a validation of the part with ABS printed with 100% infill.
The results above are from the optimization using CF Nylon printed with 20% infill and local reinforcement is shown in Figure 5.
Figure 5: SmartSlice™ optimization results
By selecting the optimization, the software quickly optimized the part and produced the solution above in Figure 5 with two modifier meshes to increase part strength and rigidity where it was needed. This solution exceeded all our requirements while keeping the print time and material usage to a minimum.
The shift from traditional manufacturing to additive manufacturing is a common trend in the industry, and this is being driven by lower manufacturing costs and incredible time savings that translate into huge cost savings. SmartSlice™ is another tool in a user’s toolbox to help improve these jigs and fixtures to meet the demands of the parts and budgets. The use of SmartSlice™ and additive manufacturing to create these jigs and fixtures will help companies improve efficiency and help push the limits of this industry. In the next blog post, we are going to dive deeper into the cost of making a single fixture part and continue exploring the use of SmartSlice™ with the fixture part shown in this post.