Streamlined Design with Pro/ENGINEER Advanced Assembly
by Jeff Pike

When it comes to automotive safety, seat track systems play a vital role. They must hold seats firmly in place when the car is in motion, but they also must allow passengers to easily move their seats forward and backward prior to starting their cars. That’s why JR Automation, a company that produces manufacturing systems for automotive companies, as well as many other industries, must develop precise designs — meeting stringent regulatory and performance requirements — for their seat track assembly systems.

“Our seat track manufacturing machines have approximately 30,000 components,” says Vaughn McDaniel III, a mechanical engineer with JR Automation. “For a system of this size, we need to assign at least five engineers to ensure that we design, manufacture, and ship machines that meet our customer requirements.”

With this many components and engineers working on the design of the machine, development time and workflow can easily get bogged down without the proper product design software. To overcome this challenge, JR Automation relies on Pro/ENGINEER Advanced Assembly (AAX) which provides tools specifically for the top-down design of large machines.

Multiple engineers working on the same machine. “Pro/ENGINEER Advanced Assembly helps us quickly work through many design reviews,” McDaniel says. “The most important feature is that the software allows us to take a multi-prong approach. The seat track assembly system has seven processes, so it’s basically an automated assembly line within one machine. We need to use multiple engineers to shorten the design timeline for the whole machine, and Pro/ENGINEER Advanced Assembly allows us to do that efficiently.”

When designing the automated assembly system, the 30,000 parts require geometric designs that normally utilize significant computer processing and memory resources. But, because Pro/ENGINEER Advanced Assembly allows JR Automation to use skeleton models that simplify customer data, the team can operate on 32-bit machines with 2GB of RAM.

“Instead of using the full 3D CAD data from the customer all the time, we can copy just the important features, profiles or specific surfaces,” McDaniel says.

Pro/ENGINEER Advanced Assembly is particularly helpful when JR Automation performs design work on one machine within the assembly line. Engineers use a skeleton model that simplifies the data and can be repeated in other assemblies.

“This comes in handy when you deal with motion,” McDaniel says. “The Pro/ENGINEER Advanced Assembly design feature lets us put a skeleton in different locations of the assembly so we can design components directly off the skeleton.”

Design time reduced by 65 percent. “We developed the first of these machines in 2004, and it took a lot longer back then to design the machine because we did not have motion skeletons and the top-down design process that we do now with Pro/ENGINEER Wildfire 3.0,” McDaniel says. “Before, if we had a change to make, we might spend four hours loading every assembly to just make a couple of dimension changes. But now, the changes in one assembly are reflected across the board and are automatically updated as soon as you load them. This reduces our design time by as much as 65 percent.”

JR Automation uses Pro/ENGINEER Advanced Assembly motion skeletons to create a layout of the motions while streamlining the process of inserting the motions into the assembly. The motion skeletons let McDaniel and his team start with simple sketches of motions and then break that into separate bodies. The motion skeletons then allow for the placement of components to those bodies, resulting in dynamic movement of actual components.

“We previously used skeletons with static parts, but with motion skeletons, it’s more of a skeleton assembly with separate skeleton parts inside,” McDaniel says. “This automatically creates motion bodies, and when we insert a body into a sketch, we can pick motion skeleton curve entities from the layout sketch to define what’s inside the body. Pro/ENGINEER Advanced Assembly automatically calculates the mechanism constraints by making external copy geometry of the curve in the motion skeleton bodies.”

Starting with what the engineers want to accomplish. Motion skeletons also come in handy when engineers make changes: workflow is more efficient, and it’s easier to train them on how to design motions because they aren’t worried as much about parts and geometry.

“Instead of starting with the form of what an assembly is going look like, Pro/ENGINEER Advanced Assembly lets us start at the function,” McDaniel says. “That’s makes the software especially helpful for mechanical engineers. It lets them start with what they want to accomplish and then figure out how they are going to do it.”

Another feature that JR Automation relies on heavily is external copy geometries.

“Each separate machine within the assembly line must be incorporated into a single line, so each engineer needs to know where everything else is,” McDaniel says. “Our engineers interface, but they can’t have the same assemblies in session at the same time because we’ll have trouble with overwriting. We also don’t want to bring in the skeleton model of the main line because we don’t need all that information. Instead, with Pro/ENGINEER Advanced Assembly we perform copy external geometries into skeletons of specific assemblies. That lets us reference the same positions without opening all the other CAD data from other machines.”

McDaniel realizes the true value of Pro/ENGINEER Advanced Assembly when he considers what his team would face without the software.

“We would have to make bunch of references between all the components when designing an assembly. That would give us disorganized clusters of references that go in every direction. But with Pro/ENGINEER Advanced Assembly, we can consolidate references to a skeleton model so our flow is only in one direction. This makes reusing parts, replacing components and changing references much easier. We can also have a different position in every machine that needs to interact. We would spend a lot more time if we had to go back to 15 different assemblies to verify it’s correct. With Pro/ENGINEER Advanced Assembly we only have to verify it once.”