Finishing first with advanced technology

April 1, 2002
Shop delivers custom car parts in 24 hours using a high-powered, manufacturing cell.

Shop delivers custom car parts in 24 hours using a high-powered, manufacturing cell.

The Fab9 rear-end housing from Chassisworks comes in a variety of customized configurations, and its fixtures push the envelope of the FH-680 HMC.

The Palletech HMC handles a wide variety of parts at Chassisworks.

The 90° pallet indexing of the Mazak system provides operators with easy access to fixtures mounted on all sides of 12 pallet-mounted tombstones.

Chassisworks machines a 42-in. cross member on the Palletech manufacturing cell, which ensures accuracy for a stable front-end suspension system.

Chris Alston, founder and owner of Alston Chassis-works, Sacrmento, Calif., works in an industry that poses an interesting challenge. He runs a shop that designs and manufactures premium drag racing chassis and suspensions, along with front ends for high-performance classic street machines. The challenge comes in making a profit on each product sold when many of his competitors give free parts to drivers in exchange for advertising on their racecars.

To survive in this environment, Chassisworks delivers its high-quality customized components faster than those shops exchanging parts for advertising. And it does so using the high-production capabilities of a Palletech manufacturing cell from Mazak of Florence, Ky.

At the heart of the cell is an FH-680 HMC, which sports a 41.531.532.4-in. work envelope, a 15,000-rpm/50-hp/50-taper spindle, high-pressure through coolant, and 1,260-ipm rapid-traverse rate.

The cell also includes a 12-station pallet changer and loading station that indexes 90° to provide easy access to all sides of the tombstone. Once fixtures are loaded on a pallet, the system's transporter delivers it to one of 12 stations, where it awaits its turn in the HMC.

A cell controller maintains the system's machining schedule automatically, so the cell runs several jobs and pallets without operator intervention. When a job comes to the top of the production schedule, the controller retrieves the appropriate pallet using the transporter and then delivers it to the machining center.

With the system, Chassisworks meets last-minute customization demands because it is easy to interrupt the production schedule to quickly machine urgently needed parts, says Alston. A switch at the loading station lets operators fit new jobs into the machining schedule. The system's control then automatically updates the entire schedule to accommodate these sudden needs.

With every new product run on the Palletech, Chassisworks adds more tools to the FH-680's 120-station toolholder, which handles a tool and holder weighing up to 66 lb. A tool-management option in the FH-680's Mazatrol controller records 10 to 12 tool attributes including tool numbers, names, whether they are heavy or light, their Z-axis offsets and diameter values, remaining tool life, and suggested replacement times. The option also provides the spindle-thrust loads and X, Y, and Z-axes thrust values for tools.

Every tool carries an electronic chip in its retention stud that stores information about that tool. A chip reader in the machining center gathers that information for storage in the Mazatrol tool-data file.

Chassisworks requires a lot of duplicate tooling to make all its different products and expects to out-grow the system's tool-holder. "You would think 120 tool positions is plenty, but it is the absolute minimum to have on a pallet line," says Alston. "We make a phenomenal variety of parts. When you run stainless steel, aluminum, and steel parts, you end up with a lot of duplicate tooling since you have to carry the right insert grades to cut each material type. If you don't have the tools on line, you can't make the parts."

Quick components
One of the first jobs Chassisworks did on the Palletech system was the Fab9. It's a rear-end housing that fits any rear-wheel-drive car, and the shop modifies and accessorizes it per customer order. Fixtures for holding the housing are large and barely fit inside the FH-680. "It takes every bit of the work envelope to machine this part, which is why we bought the 24.8-in.-pallet model," says Alston.

To accommodate all the possible configurations, every Fab9 fixture remains mounted on one of the 12 pallet-mounted tombstones. As an order for a particular configuration comes in, the operations manager puts it into the production schedule for machining.

Once the schedule is downloaded, the cell knows which pallet holds the appropriate fixtures for that order. The cell informs the operator of the schedule, and he then retrieves the pallet and loads the parts.

For the first two years of operation, the Fab9 was the only product machined on the Palletech. When the shop finally did start machining other jobs on it, the cell produced parts in hours that would otherwise take weeks.

Some of these other jobs include street-machine frames and front cross members. The frames, which are for Novas and Camaros, come with a variety of accessories involving a large number of parts. According to Alston, an operator's job is fairly minimal when running these frames on the HMC. In fact, they simply load parts and go off to do something else.

For its street-machine 4 2-in. front cross members, Chassisworks machines the entire structure and its billet steel accessories on the Palletech system. "Our competitors weld these pieces from sawed tubing, but machining the cross member and its billet mounts produces a much more desirable look for our product. The look of a product is very important in the street-machine market," says Alston.

Chassisworks forms cross members on a rotary bending machine and mounts them upside down in an adjustable-width fixture on the Palletech. The machining center bores the holes for attaching the upper and lower A-arms, shock mounts, and rack-and-pinion mounts to the cross member.

Accuracy is the reason for machining cross members, says Alston. Location of suspension points are critical to how well a car steers. By machining all the parts, Chassisworks has much better control over the finished dimensions of the part.

The shop also uses the Palletech cell to machine kitted parts. This enables it to machine, in one setup, all the parts necessary to make a complete assembly. Today, the cell runs 35 products that represent different part families.

"Parts coming off the Palletech may be almost identical, but they do have some variations," says Alston.

"This means we may actually have 100 different part numbers being machined in a single week. The Fab9 housing, for instance, with its variations, represents 50 different part numbers."