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Five-Axis Machining Lifts Shop's Part Productivity and Quality

A key part Sport Truck makes for its lift kits is the steering knuckle, a complex component the shop machines on Mazak horizontal and vertical machining centers, including its most recent VARIAXIS i-800 5-axis VMC with rotary/tilt table and 50 taper spindle.

The two-pallet changer on Sport Truck USA's Mazak machines provides additional unmanned operations and off-cycle part set-up.

According to Manufacturing Engineer Caleb Phair (left) and Design Manager Jared Ball (right), both of Sport Truck USA, the shop was able to eliminate three operations, reduce production lead times, improve machining accuracy and lower operating expenses due to its Mazak machines, including the VARIAXIS i-800.

For its knuckle components, Sport Truck USA machines the part, complete and ready-to-ship, in one set-up due to the DONE IN ONE part processing technology of its Mazak VARIAXIS i-800.

The Mazak VARIAXIS i-800's advanced multiple-surface, simultaneous machining capabilities that include milling, drilling and tapping proved ideal for the Sport Truck USA's knuckles' profiled surfaces.

Coldwater, MI-based Sport Truck USA (Sport Truck), a division of Fox Factory Holding Corp., knows a thing or two about automotive suspensions. Since 1991, the shop has been designing, manufacturing, marketing and distributing high-quality aftermarket off-road suspension components, such as lift kits for pickup trucks and 4x4s, through its family of brands that includes BDS Suspension, Zone Offroad Products, JKS Manufacturing and 4x4 Posi-Lok. But as consumer demand grows for suspension lift kits for today's newer, more sophisticated models, so too does the need for more complicated parts necessary for those kits.

A key part Sport Truck makes for its lift kits is the steering knuckle, which also happens to be the most complex component and one that takes the longest to make. The part is critical because it keeps a vehicle's upper A-arm in the stock location while being lifted. The quality and supply of knuckles are critical to the shop's continued success.

At one point in its manufacturing operations history, Sport Truck machined only one model of knuckles on its 4-axis horizontal machining centers (HMCs) and outsourced the production of other models to a local machinist. But lead time, costs and production volume increases forced additional knuckle machining production back in-house at Sport Truck, according to Design Manager Jared Ball.

"Today, we machine most knuckles in-house so we can control the quality to our high standards," Ball said. "When we tried outsourcing overseas, and performed our quality testing, we were finding only about 80% of the finished product met our standards. It was an expensive learning process. The fit of the knuckles is critical to the overall performance of our kits and to meeting customer expectations, so how they are machined is equally as critical."

But more manufacturing change was on the horizon for Sport Truck in 2015. That is when the shop received a project for the new model year Ford F150 pickup truck. The vehicle's new design required a more complex knuckle, in particular, one with a compound-angle design.

"We asked ourselves if there was a different, more efficient way to make the part," Ball explained. "That is when we began our search for a machine technology that could do more and give us higher levels of efficiency to produce those complex parts in fewer operations."

As a long-time Mazak customer, it did not take long for Sport Truck to contact its Mazak distributor, Addy Machinery, to help identify a solution. The shop knew it wanted an easy-to-use machine that would combine operations and reduce set-up times so the shop could quickly and efficiently deliver products to market faster and keep up with the trend of more sophisticated-and frequent-vehicle suspension design changes.

That solution turned out to be a Mazak VARIAXIS i-800 5-axis Vertical Machining Center (VMC) with rotary/tilt table and 50 taper spindle. It was perfect for the shop because of its advanced multiple-surface, simultaneous machining capabilities that include milling, drilling and tapping-ideal for the knuckles' profiled surfaces. As a result, the shop was able to eliminate three operations, reduce production lead times, improve machining accuracy and lower operating expenses.

"We were already using the 4-axis Mazak HCN-6000 HMC," said Ball. "One of the good things about it is that it is the same machine that our other suppliers use when they make parts for us. And it is the reason we got the 5-axis VARIAXIS-we already trusted Mazak machines and knew they were reliable and user friendly in addition to being able to make quality parts."

The shop saw immediate boosts in production efficiency and accuracy. According to Ball, competitors were using a horizontal plane, three chuckings and multiple operations to produce a single knuckle. On its VARIAXIS i-800, Sport Truck now machines the same part, completed and ready to ship, in one set-up made possible by Mazak's DONE IN ONE technology. Operators only touch parts twice-once to load and again to unload-as opposed to moving parts around the shop to multiple workstations.

"For us, this is a huge deal. I have been on the technical support side in the years I have been at Sport Truck, and something you never, ever want to hear from a customer is that a part is not meeting their expectations," said Ball. "One of the things about Mazak machines, and the VARIAXIS i-800 in particular, is that they can make the same identical part every single time, without quality issues, which results in a better customer experience."

The machine also features extra tooling capacity for longer unattended operation. Its higher feed and speed capabilities generate smooth surface finishes, while a high-pressure coolant system helps extend tool life.

When paired with an optional two-pallet changer, the machine provides additional unmanned operations and off-cycle part set-up. This simple, efficient form of automation allows the shop to load, unload and inspect parts on one pallet while the machine works on the other one. The machine's MAZATROL SmoothX CNC offers easy 5-axis programming and, according to Ball, the control's touchscreen functionality linking program, process list and 3D tool path display enables him to take 3D models of the fixturing and use the screen to easily program the job.

Sport Truck began in 1982 as a retail store specializing in lifted suspensions. Through a series of acquisitions over the next few years, the company broadened its product offerings until, in 1994, it began focusing solely on suspension products. The shop prides itself in making high-quality parts and backs them up with customer care programs.

Today, the company has around 275 workers. The shop's production operations include machining, laser cutting, sheet metal fabricating, CNC robotic welding and manual welding. For its suspension kits, the shop produces, in addition to the knuckles, control arms and shock bodies.

"The biggest thing in our business is being first to market, so part production cycle time is important. When a new model truck comes out, we want to be the first to get a kit for it out in the market," said Ball. "Being first to market with a quality kit has driven our business and resulted in consistent growth over the years."

Ultimately though, Ball added, it all comes down to taking care of customers. "If you do not, they are not coming back to you-they will go to your competitor," he said. "The reason our customers keep buying from us is because we make excellent products, they are confident in our quality and they know they are getting the best support. It is a model that has worked for us and one that would not be possible without our Mazak partnership."

For more information contact:

Mazak Corporation

P.O. Box 970

Florence, KY 41022-0970




Steve Addy

Addy Machinery Co.

36055 Groesbeck Highway

Clinton Township, MI 48035




Peter Addy

Addy Machinery Co.

3757 Broadmoor Ave SE, Ste. A & B

Grand Rapids, MI 49512


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