CNC Horizontal Milling Machines Add Flexibility for Creative Tools and Workholding

“Material costs have been rising dramatically for several years,” says Dan Seacat, co-owner of Apex Precision Technologies of Camby, Ind. “On top of this, customers want parts cheaper and faster. Most think there’s no choice but to pay more, charge less, and watch your profit margin shrink. That couldn’t be further from the truth.”

Apex overcomes this challenge by utilizing machine tools that allow them to implement combination cutting tools and custom fixtures, created for their customers’ orders. Seacat, who is also Apex’s engineering shop floor manager, says that it’s the time savings of their custom tools and flexibility of his Makino CNC horizontal milling machines that allow his shop to meet the just-in-time delivery requirements.

“Most of our orders are for big contracts delivered in kanban quantities to large, demanding customers,” says Seacat. “So we have two contrasting needs: we must produce large quantities, but in small batches. These kanban orders demand flexibility as much as speed. Our response was to develop internal capabilities to design, build, and utilize custom cutting tools and custom workholding.”

Apex relies on their Makinos to provide fast, flexible machining to utilize their uniquely crafted tooling.

“When you’re using large, heavy tools up to 9.25 inches in diameter and 40-plus pounds, you need a strong, accurate, reliable machine,” says Seacat. “Our investment in Makino a81 CNC horizontal milling machines met these flexibility needs, while providing an excellent chip and coolant removal system, rigid spindle design, superior axis travels, extended tool life, rapid tool changes, and the torque required to handle our frequent cast iron machining operations.”

History

Apex Precision Technologies was founded in 1953 in southwest Indianapolis. The company produces large parts for many well-known off-highway vehicle and automotive suppliers, specializing in differential housings, transfer cases, and axles.

Apex has been management owned since 1993 and is today run by Jerry Jackson, who started his employment at Apex as a lean management consultant. His lean techniques have helped to grow Apex from a $7 million per- year business in 2003 to $27 million in 2007. The company was certified ISO 9001 in 1997 and ISO 14001 in 2005. The most recent benchmark achievement for Apex has been the Toyota Forklift Supplier of the Year award for 2007, where they beat out 149 other top suppliers. Apex’s current 40,500-square-foot location is packed with 30 machine tools and other equipment.

“Our lean approach involves more than cutting down on waste materials,” says Jackson. “True lean facilities also look for reliability, versatility, and flexibility in both programming and machining technologies. With limited floor space, we need machine tools that can demonstrate those qualities, which is exactly why we purchased the Makino machines.”

Flexibility

Apex first purchased a Makino A55 in 1993, a second A55 the following year, followed by A77s shortly thereafter. Several Makino A-series CNC horizontal milling machines were put into a Makino Machining Complex (MMC), used to run large quantity jobs. This lean MMC has provided Apex with higher spindle utilization and decreased cycle times with little operator intervention.

The company has since invested in several newer large horizontal machining centers from Makino, including an A88, three a81s, and most recently an a81M. The new a81 CNC horizontal milling machines have demonstrated exceptional performance and trusted reliability

The a81 machines act as dedicated equipment for quick-run operations and kanban parts. The A88 and A77 machines produce a variety of smaller quantity parts. Some short-run or common-designed parts run on the A77 MMC.

“We push the Makinos hard,” says Seacat. “With these CNC horizontal milling machines, there’s no reason not to push the limits. Around the shop, our motto is ‘If it ain’t glowing, it ain’t going,’ and the last thing we need is to have to hold back because the machines can’t handle the workload. These machines can take a beating, and many of our combination tools prove it.”

Combination Tooling

Apex’s engineers and programmers have become highly skilled at developing custom workholding to reduce tool changes and increase machining efficiency. The custom cutting tools have ranged from 0.150 to 9.25 inches in size and weigh up to 40 pounds or more. Tools are typically composed of carbide or steel with replaceable inserts.

Apex’s combination tools can typically perform multiple operations, such as a tool that drills a hole, shoulder mills, and finely finishes bores to complete a feature without the need for a tool change. Tools capable of more than one operation allow the company to speed production times significantly, reducing out-of-cut time, limiting tool changes, saving space in their tool magazines, and applying the most efficient machining process to each feature. In addition, because they design custom cutting tools that will be performing operations in the same area of the part, they can often speed programs to go from one operation to another simply by changing the depth of cut. “It isn’t uncommon for a part to require 50 or more tools each time it goes into a machine,” explains Seacat. “With this many tools, we need fewer and faster tool changes out of our machines.”

Tools usually have several layers to them, each separate operation moving farther back onto the tool shank.

“These custom cutting tools may look crazy,” Seacat says, holding a 9-inch monster of a tool with a drill on the end, large-diameter boring inserts in the center, and even larger boring inserts farther toward the back. “But they get the job done much more efficiently than changing out a tool each time we need a new operation. On top of this, we’ve seen our scrap rates decrease since we’re custom-making tools for each application. Low scrap means less material costs. We’ve also seen noticeable differences in tool life, resulting in even fewer tool changes and lower tooling costs. When we do have to go to the ATC for a tool change, the Makino machines are super-fast, about two seconds.”

Speed becomes especially important when a customer’s kanban quantities suddenly change.

“When you go from 120 pieces due this week to 350 due next, with only a few days’ warning, you have to be able to adjust your production quickly,” explains Seacat. “We achieve this through our MMC, high-performance machining centers, and our custom cutting tools. There’s no time for inflexibility. These kanban parts need to be made very quickly and efficiently.

“We have a customer that used their facilities in Japan to show us an example of how they thought the part could be most efficiently produced. Their facility produced the part in four operations, and was very surprised when we came back to them with the same part, produced in only two operations.”

To run their combination tools, Apex relies on machines such as the Makino a81s for low-end torque, low spindle run-out, and the ability to handle long and heavy tools.

Combination tooling can be quickly implemented by Apex, oftentimes produced in less than two days and cut within a week of development. They are frequently designed for specific operations that would otherwise cause slowdowns in the machining process, such as finishing the inside diameter of large holes or reaching through a window fixture to cut a specific feature.

“Not every machine can handle our tooling. For example, the Makino’s spindle face is only 50mm from the pallet center, which allows us to use long tools and not lose rigidity,” explains Seacat. “When your machine places strict limitations on you, it forces you to compromise in your tool and fixture designs.”

Custom Workholding Fixtures

Beyond tooling, Apex routinely customizes their fixtures to allow for faster production times, toolpath optimization, and to allow their custom tools to reach part features standard fixtures wouldn’t allow.

“We look at each job as an opportunity to create the best manufacturing scenario,” says Seacat. “Once we’ve determined custom workholding that will work, we’ll often create a fixture that will maximize our efficiency, and enable us to machine critical features in the first or second operation to limit the potential for stack-up error. Sometimes we use hydraulics, or window fixtures, or some other trick to make the fixture work around our creative programming and tooling.”

With window fixturing, they are typically able to bore large holes complete in a single operation or machine features on the back inside or back of the part, cutting down on time spent re-fixturing to complete the part. Hydraulics allow for variable part clamping or easy part loading and unloading. “Every second counts,” adds Seacat. “We use creatively built fixtures to reduce time spent out of the cut, limit setups, and to get the most out of our custom tooling.”

Seacat credits much of Apex’s ability to use combination tools and customized fixtures to the flexibility, speed, and reliability of its Makino machines. He says the more compact and stable spindles allow for tools to reach farther without the need for extended tool holders, a common issue that leads to rigidity concerns. The Makino horizontal machining centers also perform as well high in the Y-axis as they do at the base of the pallet, allowing Apex to create tool paths that cut far above the center line without worrying about rigidity or loss of accuracy.

“Our guys can get deep into holes or pockets, reach through window fixtures, or design monster tools that are much more efficient. The stroke and overall design of the Makinos allow them to get farther from the center of the pallet and farther up in the Y-axis, while retaining the accuracies we need. We can push those machines hard and not worry about the machine crying ‘uncle’,” says Seacat.

Parts Perfect for Custom Cutting Tools

“Oddly designed parts are a blessing in disguise if you know what you’re doing,” says Seacat. “It takes custom designs to produce odd parts, but not everyone is able to readily produce them, making it a niche market for our shop.”

Apex recently machined a transfer case that required a 7.874-inch diameter bore with a chamfer that had to be accurate within ±0.001 inch. It features a 63-micron tolerance and is 2.5 inches deep and a 0.004-inch diameter true position. This part raised concerns due to cycle times, the amount of stock to remove, interrupted cuts, parting lines, core prints, and a large-diameter bore that required a lower rpm. Apex’s solution was to design a custom tool that would allow roughing, semi-finishing, finishing, and chamfering, all with a single tool, cutting down the number of operations and consumed magazine space from tools.

Another part Apex recently dealt with required a 4.249-inch ±0.001 tolerance through-bore with chamfer, and a roughed, 1.259-inch diameter hole with the same tolerance that needed prepping prior to finishing. Above that was an M60 x 2 thread that needed the minor diameter machined and a chamfer cut. The company was concerned with the combined cycle time and potential stack-up error of six operations, a large consumption of magazine space due to multiple types of tooling, and the difficulty of working with a cast solid part. Apex was able to produce a single 13-inch tool with replaceable inserts that completed all the necessary operations with the required accuracies for each feature while saving magazine space for other large tools. Utilizing a window fixture, they were able to machine all the way through both bores in one setup.

After completing this part, Apex was challenged with an alternate version of the same part. It required a similar 4.249-inch diameter rough, finish, and chamfer operation for the main bore, but with an additional M16.0-by-1.0 tapped hole. Since cycle time, due to multiple operations and many tool changes, was a factor, a combination tool was again applied. The tool incorporated a collet chuck/tap in the tool, which allowed reduced tool changes.

“Combination tools and custom fixtures can seriously reduce out-of-cut time, reduce tool changes, and allow you to perform multiple operations in one setup,” comments Seacat. “But there is a high potential for error when using long, complex, heavy tools. We rely on the Makinos to provide the stability required to handle unbalanced tools and versatile fixtures.”

The Future

“Lean principles are built on many different factors—one of the primary principles being process stability,” says Jackson. “This is exactly what the Makinos provide, even with our guys pushing the machines with customized fixtures and multiple-operation tools. The stability and predictability of these machines allow us to bid orders and promise lead-times with confidence.

“We’re fighting the same battle everyone else is: Customers want parts faster, cheaper, and they don’t necessarily care that material costs have skyrocketed. Thanks to the creativity of our designers and machinists, and our Makino horizontals that are allowing us to do custom workholding that most others can’t create, we’re on track to nearly double our business by 2010.”