Overcoming Racing CNC Machine Shop Challenges

A big part of my International Manufacturing Technology Show (IMTS) experience this year—more so than at past shows—involved video interviews and conference presentations. It was the same for many of our company’s other editors. In my case, I was interviewed for IMTS TV, I moderated a workforce development panel at our Top Shops workshop and I moderated an ExxonMobil/Stewart-Haas Racing (SHR) panel that was live-streamed to more than 7,000 online viewers.

That live-streamed panel consisted of Tony Stewart, three-time NASCAR cup champion driver and SHR co-owner; Brad Harris, SHR director of CNC operations; and Ray Salazar, ExxonMobil equipment builder engineer. We talked about a variety of topics, but the event largely described how SHR’s in-house machine shop, like other shops serving automotive race teams, closely resembles a job shop. Both deal with high-mix/low-volume work, look for ways to speed setups and remain flexible, as they might not know what work will come through the door on any given day.

In the case of SHR’s shop, team engineers are continuously developing new racecar components or tweaking existing designs to minimize component weight and maximize strength. (The racecars have a minimum weight requirement, but reducing the weight of certain components enables the team to add weight in targeted areas to improve performance.) Like many job shops, they’re also continuously looking for ways to leverage new technology, apply new shopfloor practices, and provide an environment in which all employees are sufficiently trained to not only effectively handle their current duties, but to learn new skills and grow within the company. Here are a few of my takeaways from the 45-minute discussion related to those points:

• Five-axis machining. SHR’s shop has 21 Haas Automation CNC machines: seven turning centers and 14 milling machines. Ten of the milling machines have five-axis capability, which Brad says the shop is increasingly using. The vast majority of five-axis operations performed is 3+2 positioning work, although some full contouring is performed for complex parts. The latter, in particular, gives the team’s engineers additional freedom to design parts with intricate geometries that result in stronger and lighter parts. Good examples of this are the team’s front spindles, each starting from a 450-pound block of steel and requiring upward of 20 hours of total cycle time.

That said, 3+2 positioning enables the shop to reduce setups while maintaining feature-to-feature accuracy being that the tool can access five sides of the part in one fixturing. Because part rotation provides less-impeded tool access to the part, shorter, more rigid tools that can take more aggressive cuts can be used to minimize cycle times. This has helped speed part delivery time in the team’s “need it yesterday” production environment. Brad says the team has had help not only from partners such as Haas Automation and ExxonMobil, but also from Mastercam, Camplete and Kennametal as it has worked to establish its effective five-axis processes.

The lesson here is not to shy away from new, advanced technology, such as five-axis machining, because there are a variety of resources to assist you with the learning curve. 

• Unattended machining. The two-shift SHR shop works to implement unattended machining as much as possible these days including lights-out machining when it makes sense. Running unattended during the day frees operators to tend other machines or perform other value-adding tasks. Parts with very long cycle times, such as the front spindles, are typically machined overnight. Brad says the key to establishing a reliable, predictable lights-out process begins with effective CAM programming as well as toolpath simulation to verify that there will be no “bumps in the night.” Other process elements include in-process tool-breakage-detection routines, adequate chip management and the ability to maintain proper coolant levels. Effective machine tool component lubrication is important, too, especially when you consider that machine spindles will be running at high speeds for a long period of time.

The lesson here is to think about ways to gain longer stretches of unattended machining, not necessarily lights-out, to maximize the value of employees’ available time on the shop floor.

• Knowledge sharing. Tony says teamwork has played a big role in his racing success, pointing to the value of surrounding himself with talented people. Similarly, Brad points to the value of the machine shop’s ongoing training efforts and, in particular, encouraging a team environment and establishing a culture in which knowledge is freely shared among everyone. This is especially important to help new employees grow their shopfloor talents and become more valuable team members.

Design for manufacturability (DFM) is part of this, too. Brad says the shop strives to manufacture precisely what the engineers design, but those engineers are open to suggestions from the shop for ways to speed and simplify machining. This can reduce production time and cost. More job shops are offering DFM advice these days to their customers for similar reasons.

The lesson here is to provide employees with a means for building their skillsets, which sends a clear message that your shop provides a path to a successful manufacturing career.