Manufacturing Engineering

"Software Supports a Good Ride"

February 2007

Getting the perfect ride in a car has always been a compromise. If the suspension is stiff for responsive handling, it jars your teeth. When the suspension is soft for comfort, the car takes curves and turns like a boat wallowing in the surf.

There is a better way to eliminate this handling compromise. That's where Air Ride Technologies (ART; Jasper, IN) and its founder, Bret Voelkel, come in. Ten years ago, Voelkel, a car enthusiast, designed an air-ride system for his 1970 Mustang Mach 1. He wanted a suspension that would handle drag racing while giving him a comfortable street ride. The air-ride suspension he developed was successful, so successful in fact, that while working in his garage, he started advertising the system and began installing them on customers' cars.

Air Ride Technologies soon outgrew Voelkel's garage and eventually moved into his current building. The metal-fabricating shop grew so much that he bought the building next to it and started a body shop to do hot rod restorations and auto body work. Voelkel's three businesses, Air Ride Technologies, Concept Design and Fabrication (a metal fabrication shop), and Precision Coach Works today employ 42 people and currently occupy 28,000 ft2 (2601 m2), among all the buildings.

Air Ride Technologies produces suspension components for a large cross-section of cars. For instance, one of its new products, the AirBar, is a four-link rear air suspension that will bolt directly into OEM leaf-spring mounts of muscle cars from the 1960s without any frame cutting or metal fabrication.

The car's ride height is typically lowered by about 2" (50.8 mm). The fully deflated height is usually 5–6" (127–152.4 mm) lower than stock height. Instead of a wallowing soft ride, the car has a crisp, controlled handling. Other products include control arms, four-link suspensions, and the patented Shockwave, which is a combination air spring and shock.

The manufactured components are not the most intricate to manufacture, but designing a full suspension kit or specific components for the various vehicles can prove a challenge. Parts are usually designed to be installed without cutting or welding the car's suspension, body, or frame. Only hand-tools are needed for mounting.

Air Ride Technologies manufactures the machined components for the air springs, such as the cap that is on top of the air spring, and the piston on the air spring's bottom end. The company uses five CNC lathes and two VMCs to machine the aluminum parts. The primary rubber components for the shocks and struts are produced by Firestone.

"I would say 80% of our parts are aluminum; 20% are steel," says Beau Anderson, CNC-machine-tool computer programmer. "Some of the components inside are steel, such as the shaft that goes through the shock, but the majority of it is 6061 T6 aluminum. We have four or five varieties of caps and pistons, depending on which air spring is used. A majority of our milling work is aluminum also."

Steel parts produced from 1018 steel or tubing stock include bushings and sleeves for the four-link suspension system. Parts produced using the lathe are about 4–4.5" (101.6–114.3-mm) diam, and roughly 1 ¼" (31.7-mm) long, while the pistons are 3" (76.2-mm) diam and 3–4" (76.2–101.6-mm) long. Bar feeders can handle stock from ¾ to 2" (19–50.8 mm) and from 1 to 3" (25.4–76.2 mm).

"I won't do anything under 200 pieces with a bar feeder because of the setup time involved," says Anderson. "On the caps and the pistons I usually do about 500 pieces per lot, which is about our smallest run. We probably do about 1000–2000 pieces on some runs."

On its mills, ART sets up parts to do multiples using dedicated fixtures or vises that can handle numerous parts. Most of their parts are simple to produce, but they use a C axis on one lathes to etch the company's logo onto the strut/shock cap.

"We'll etch our logos onto the caps, so that's somewhat intricate, and some of the parts have tight tolerances. Because these parts aren't that long and you're not holding onto much stock in the lathe, we have to watch how fast they're turned, the feed rates, and how much stock is taken off," Anderson says.

Component tolerances are tight for some parts, anywhere from 0 to ±0.002" (0.05 mm), but others have a tolerance of ±0.005" (0.12 mm). On average they hold ±0.005 (0.12mm) on most of their parts.

For programming toolpaths and fixturing, Air Ride chose Mastercam CAD/CAM software from CNC Software Inc. (Tolland, CT). "After the parts have been researched, developed, and drawn up, they'll be brought to me in a print form, and I'll program them in Mastercam and download them into the CNC machine," says Anderson. "Then I'll set the machines up and produce the workholding fixtures also using Mastercam."

Programming a part's toolpath can be tricky when the C axis on a lathe is used. Anderson says that Mastercam X (the latest Mastercam version) lathe software has made it simple. Mastercam's ease of use was evident when Anderson joined the company and started using it by trial and error after a few lessons from another programmer at the company. Later he took the Mastercam Mill class, C-axis classes, and lathe lessons.

Another feature that Anderson likes about Mastercam is its ability to make changes. "If you know how to write longhand, you can go to the machine tool and make simple changes off the G-code that Mastercam uses, which is helpful." Anderson also likes the Backplot function, because it gives him an estimated amount of time to produce a part. "It allows us to try different things with toolpaths to make the part faster, if you think you need to run the part quicker or need to make a better time with it. The Verification function is great too, because if you have any possible crashes, it will show them.

Sometimes Anderson will use the Backplot function to help price a part. "If we haven't actually built the part, just prototyped it, and we need to estimate it, we will use Backplot to get a rough estimate of how long it's going to take to machine it. We might add a little bit to the production time just for tool changes, and for loading and unloading the part into the machine."

Anderson also uses Mastercam to help build the fixtures for the parts. "I just did a fixture for one of my parts, and it was nice to go from my jig back to my part and merge them together to make sure that once I made my jig and part program, they would fit together," he remarks.

Air Ride is constantly adding new car models, street rods, and hot rods to their part roster. Each vehicle will have a different bushing or cross shaft that will be used to mount the suspension system to the car.