Combining Modular Fixturing with CAD Modeling

Find out how using CAD models can help you create and verify modular fixturing designs for increased efficiency in the workshop.

AWS Publications | July 26, 2021 | Processes
Welding Digest ►  Combining Modular Fixturing with CAD Modeling

Find out how using CAD models can help you create and verify modular fixturing designs for increased efficiency in the workshop.

In the past, fixturing a workpiece meant you had to fabricate custom fixturing elements from several parts, such as laser-cut pieces, tubing, risers, jigs, and clamping tools, just to name a few. But now, with the growing use of modular fixturing systems, designers can build fixtures quicker and more efficiently, all while reducing costs and freeing up valuable floor space. The process is facilitated further by combining modular fixturing with a computer-aided design (CAD) software.

 

Modular Fixturing Explained

What exactly is a modular fixturing system, and how can it improve your fixturing process? A modular system consists of a heavy-duty table or base platform designed with an array of equally spaced pinholes used to locate and mount fixturing elements. The pinholes can range from 5⁄8 to 1 in. in diameter for the larger and heavier workpieces. All pinholes and faces get machined to tight tolerances, allowing them to be used as a measuring tool for locating and documenting fixturing setups. Modular fixturing systems are designed to deliver enough clamping capacity to securely hold a workpiece during welding and machining processes.

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This modular fixturing system consists of the Strong Hand Tools BuildPro® Max table and fixturing devices to hold the workpiece in place.

 

Modular systems enhance versatility by enabling different types of fixturing elements to be combined to construct unique fixture structures. Fixture structures can be used to make custom risers, supports, jigs, or any tooling. This versatility is one of the most beneficial features of a modular fixturing system because of the unlimited amount of combinations that can be generated. The possibilities are limited only by the imagination of the designer.

Additionally, modular systems are highly adaptable because they can easily be torn down and rebuilt with excellent precision and consistency. Their adaptability provides space savings by freeing up the shop floor space that is usually necessary to catalog and store bulky, heavy fixtures. This also reduces the consumption of raw materials required to build permanent fixtures. A modular system’s efficiency in quickly building fixture structures is significant when working with short production runs where investing precious time and materials on designing and building permanent fixtures is not an option.

 

How CAD Facilitates Fixture Design

There are many advantages to using CAD, making it a valuable tool to include in the design process. For example, if you have ever needed to design a fixture for a workpiece that contained odd shapes, angles, or planes, you know that this can sometimes become a challenging task. The CAD software simplifies this task by allowing the fixture to be designed in a virtual 3D environment (see lead photo). This 3D environment eliminates the physical restrictions that slow people down when they go through the process of building a fixture in real life. A user can design and verify a complete fixture setup using CAD in a fraction of the time it takes to build one physically, and all without having to set one foot onto the shop floor.

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This modular fixturing system utilizes the Strong Hand Tools PRO28 table to aid in the production of a large rail.

 

Another benefit of working in CAD is that the user can test fixture setups with fixturing elements that might not exist in the shop, enabling components to be tested before they areacquired. CAD also gives notification alerts for problems that may arise, which helps users analyze part geometries for possible collisions between the workpiece and fixturing elements.

 

Important Fixture Design Principles to Follow

There are numerous benefits to working in a 3D environment, but it is essential that fixture design principles are followed to attain those benefits fully. For starters, fixtures should always be designed to ensure the workpiece is secured well enough to maintain a solid and consistent hold on the workpiece. Users should make sure the fixturing table or base area is large enough to locate and hold down the workpiece securely with enough room for locators and stops to be set up around the workpiece. When the workpiece is considerably smaller than the table, it should be placed near the edge or corner of the table to give the operator proper access to the workpiece. It is also a good idea to check the latest CAD model is being used, and it is dimensionally accurate.

Additionally, most modular fixturing system manufacturers provide CAD models that a user can access online and download for free. It is good practice and a big-time saver to store CAD models locally and organize them into a library with the fixturing elements that will be used.

Lastly, it is crucial that mates in the CAD model be used appropriately. In almost every CAD application, mates are used to locate and position components in space. In a 3D environment, mates should be applied to components to define and fix their locations. Mates also create relationships between the mating faces of all interfacing parts. It is important that mates be applied to CAD models in the same way the components will interface in real life. In other words, the mating faces of stops or locators that will press against the workpiece should be the same faces used to fix the CAD model into place.

 

Conclusion

Modular fixturing systems provide clamping abilities to securely hold a workpiece in place during welding and machining processes. The greatest benefits of modular fixturing systems are their versatility and adaptability. Despite these benefits, creating fixtures can be challenging, especially when odd geometries are involved. CAD software simplifies this task by allowing users to design fixtures in a virtual 3D environment. However, there are several fixture design principals that must be followed to obtain the full benefits of creating and verifying modular fixturing systems in CAD. When used correctly, CAD can help you increase efficiency in the workshop.

 

This article was written by Joel Chinchilla (marketing manager at Strong Hand Tools) for the American Welding Society.