Objet designed a calibration jig for the orthogonal alignment of the X, Y and Z axes on its 3D printing systems. The design goals were to make production of the jig more efficient and to significantly improve machine performance while keeping the integration time as quick as possible. The same process can be applied to designing jigs and fixtures for almost any purpose.
The cost of the jig was expected to be as high as $15,000-20,000 due to the large machine size and the high accuracy setting requirements. It was necessary to remove all major program risk as early as possible in the development period to make the jig work properly from the outset. Several key areas were identified where using an Objet 3D printer to print models for the development of the jig:
The jig was designed to attract the bearing shaft into the proper location using strong static magnets. In order to have precise repeatable shaft positioning, the magnets were to attract the shaft into a V-block. The 6kg shaft load sat high above the area where the attraction magnets would be placed and it was not clear how easy it would be for the jig operator to apply the attraction force and how effective the final attraction force would be. Questions remained such as will the operation be smooth or cause the shaft to strike the V-block and how easy will the operation be? Also, it’s well known that the attraction force quickly disappears a small distance from the attracted object – would this cause a risk?
We printed all the parts involved in the bearing attraction mechanism before we had even completed the jig design. The parts were printed using Objet’s VeroBlue material. This enabled us to perform a fully functional test for the attraction mechanism the day after the model’s completion. This is an example of how Objet can help the development process run more smoothly while removing major risks at an early design phase.
2. Work Processes Efficiency
The jig was designed to completely change how the system’s integration and calibration are performed. For the integration team members, it was important to verify the work processes hands on – something that would be impossible with only a presentation. Printing a full-scale jig and simulating all setting and calibration activities enabled us to debug the jig and fix design problems before final manufacturing. This provided us with a high level of confidence in the design early on in the project flow. The large scale jig was built and integrated a week after the initial printing.
3. Form, Fit & Function Test
Often, how the jig fits into the machine is not fully documented. In machine design, components like cables, pipes, cable chains and other flex items are not always documented at the CAD software level. As a result, when designing a jig there is the risk of not taking into consideration a component that already exists in the machine that is not documented. In addition, the access verification required for proper jig function and operation is not easily performed in the 3D modeling environment. Therefore, it is advantageous to print out a design model at a 1:1 scale to test its form, fit and function. Printing 3D models also allows you to check the effect of the design on components adjacent to and functions related to the jig.
Printing a functional model early on in the development process supports the early identification of potential errors and lets you fix them without impacting the overall program. By practicing the work processes, we were able to locate a critical error that would have caused a delay in the integration if we had waited for the final product to be manufactured.
Finally, the jig print enabled us to identify items that had to be fixed at the machine level and at the jig level in order for the project to successfully meet its goals.
The material cost of the jig was ~$1,000 – well worth the price for a product with a final cost of $15,000. The cost of fixing the errors at the final product level (which is what we would have had to do if the 3D models were not used early in the process) was estimated at $1,500, and more significantly did not include the cost of the expected delay of at least six weeks in the project flow. Hence, by using 3D printing during the design and development of the jig, Objet eliminated the cost of the late-stage fixes and also avoided the time delays.