Weld fixture validation and run-off is obviously a critical step in the fixture building process. If the fixtures are commissioned on the manufacturing floor and don’t produce good parts consistently and efficiently, then the return on investment (ROI) for the weld tooling is greatly reduced. So how do you assure the fixtures will work seamlessly once they arrive on your loading dock?
There are several different options depending on project scope and complexity. Variables such as manual or robotic welding, logistics, part complexity, and timelines are all factors in determining the best method for fixture validation and run-off. In this article, we will go over our most common processes and point out a few of the major points to consider when determining the best way to handle the run-off of your next tooling project.
The first step is always to inspect the fixture. This seems like a no-brainer, but often folks want to start by checking the fixture using their parts. Start with a good fixture as a baseline, then start seeing how your parts fit-up. If you don’t have a baseline starting point, you can end up going in circles trying to get good parts out of the fixture.
The fixture has been built with shim ability, we always start with shimming all the datum points to nominal. This also helps with establishing a baseline to start.
We use Faro arms to validate all our fixtures and have found them to work the best for efficiency and accuracy in inspecting fixtures. We import a 3D model of the fixture and inspect directly off the model, saving an incredible amount of time versus the old school method of inspecting from 2D prints.
To be honest, sometimes this is the one and only step in the fixture validation process for us. Once the fixture is inspected and shimmed as needed, some customers are satisfied and can take it from there. It all depends on the customer’s needs and requirements.
Once the fixture has been inspected and shimmed to nominal (if required), you can start fitting up loose component parts in the fixture. Of course, you want to coordinate the logistics for the component parts well before you are ready for fit-up. We start to coordinate that process right from the beginning of the project. Sometimes component part timelines and availability are major factors, if not the driving factors, in the project timeline. Especially if the component parts need to be tooled up as well.
A cautionary pro-tip; it’s important to differentiate between hard-tooled and soft-tooled or prototype components. If you are using soft tooled or prototype components for fit-up, be cautious when adjusting the fixture to accommodate the component parts. This is especially true for component parts with complex bending or forming. You can spend a lot of time and resources adjusting a fixture to be production ready using soft-tooled and prototype parts to only find out your hard-tooled parts are totally different, and you need to adjust the fixture all over again.
An important factor in the fixture design and functionality is the ease and simplicity for loading the component parts. This part can be easily overlooked in the design process, especially for inexperienced designers or designers that have limited experience working on the manufacturing floor using fixtures in the weld process.
However, testing the fixture for part loading and unloading is a large part of the fixture validation and run-off process. You make an investment in weld tooling to decrease labor and increase efficiency. Every additional second a welder spends loading a fixture is cost; and being intentional about the loading process helps drive those costs down.
Another equally important factor in the design and functionality of the fixture is the ease and simplicity to unload and get the finished weldment out of the fixture. No one wants to invest in a fixture that only produces one part, and no one wants to disassemble the fixture to get the part out! If this happens on your production floor, I guarantee your welders will not be impressed. It seems like it should not have to be mentioned but when you are dealing with complex 3D assemblies that start as loose parts and are then fused together using heat and molten steel, figuring out a way of getting the weldment out of the fixture can be a major issue.
After all the components have been individually verified for fit-up, it’s time to start welding parts. Our preferred method is to tack the parts, not fully weld. Unless the fixture is on a robot and you are performing run-off in the robot cell with a defined weld process, fully welding parts causes additional variables that can create problems that don’t need to be solved. In our experience, it is better to simply tack the parts first to initially validate the fixture. This eliminates the large variables from weld pull initially. Once the fixture has been initially validated and you have a baseline starting point, you can start to shim the fixture to accommodate for weld pull.
Another cautionary pro-tip; if you are manually welding be sure to have a defined weld process while shimming and adjusting the fixture. Weld pull can create significant variables. If you don’t have a defined and consistent weld process, you will just spin your wheels and go in circles trying to get good parts out of the fixture.
Checking for weld access in the “real world” is also an important step. Of course, you should always be checking and verifying weld access during the design process in the 3D software world, but we all know there are often variances between the perfect world of CAD and the “real world”. With the all the advancements in software and technology such as robotic weld simulation, verifying weld access in the design stage has become more reliable. However, there are often unseen variables and modifications needed.
This is especially true with manual welding applications. Humans don’t have many of the axis and movement constraints that robots do and can adjust in real time. However, they do have reach and sight limitations. They need to be able to reach the weld and see the weld. This also needs to be done in a production environment, not just once. Making sure there is not only adequate weld access but the ability to stabilize and have a clear line of sight is critical to producing consistent welds throughout production.
Ergonomics and safety are major focus points in our modern manufacturing environment. Testing the fixture for safety and ergonomics is a crucial step in the validation and run-off process. Simple safety issues such as pinch points or loose parts falling out need to be addressed and eliminated. These issues are obviously addressed in the design phase, but safety and ergonomics need to be top of mind and validated during the run-off process as well.
With ergonomics and safety being such a major focus in today’s manufacturing environment, we often incorporate our product line of positioners or trunnions with the weld tooling in manual welding applications. If you want to learn more about our Pozitioner product line, click here. The overall functionality and safety of this equipment also needs to be validated in the run-off process to verify the tooling and the positioning equipment work seamlessly and safely with each other.
Lastly, overall fit and finish need to be tested and reviewed. Weld tooling is a significant investment, and quality is always in the details. Simple things like deburring properly and eliminating any sharp edges. If there are sub-plates or changeovers, are the locating pins and fasteners removed easily? Are all the bolts tightened properly? Are there any leaks in the airline or hydraulic hoses? Does the fixture clamp and unclamp easily and consistently?
We have a checklist specifically addressing these factors and more. Again, quality is in the details. Being intentional about all the “little things” and paying attention to the subtle details is how you provide excellent weld tooling to customers.
These are just a few of the factors to consider when performing fixture validation and run-off. Having over 20 years of experience as a company designing and building fixtures, we have created a robust fixture validation and run-off process. We look forward to going through the fixture validation and run-off process with you and your team on your next tooling project!