“Either we stay ahead of the curve with the latest in machining technology or we go bust like so many other shops.” – Gary McAfee, McAfee Tool & Die (MTD), 1990.
Mating parts of punch-form blocks must align perfectly to properly form sheet metal into automotive components.
Photos courtesy of CNC Software Inc.

Three-dimensional milling has been a part of McAfee Tool & Die (MTD)’s repertoire for more than 30 years, but CNC machines, cutting technology, and its programming software have all changed dramatically.

Today, MTD’s shop includes:

McAfee was one of the first to notice the increased popularity of the unibody design in automotive engineering. In the 1970s through the 2000s, when increased fuel economy standards paved the way for lighter, more fuel-efficient cars, many manufacturers strayed from the body-on-frame style and began building the chassis and body as one. MTD was quick to offer new tooling and full replacement support for this new style of manufacturing.

Challenging parts

McAfee recently produced a punch form block, one of the many die components in unibody manufacturing. This form block, machined from a solid piece of steel, mates with another tool to form sheet metal with high accuracy. The forms then act as tooling in form dies to stamp the parts that make up the automotive frame. Plant Manager Joseph Lysiak says, “This is a very hard piece to build because there’s nothing straight. Everything is angles and curves, but it all must be so accurate because we don’t have that frame rail underneath. All the parts must fit and match perfectly.”

Programmer, Ben Ohler, explains that the best tool he has for meeting these tight tolerances is CNC Software’s Mastercam CAD/CAM.

When he had to figure out how to make the piece from start to finish, he spent most of his time within the software’s stock modeling feature, tinkering and tweaking the design. Ohler’s goal was to create the most efficient program with the best results possible. He used advanced roughing techniques that slash cycle time while keeping the stock material safe.

“We used a dovetail to hold the part, which allowed us to clamp on a small portion of the block and leave the rest open. This meant we could see more and rely heavily on OptiRough,” he says, referring to the high-speed, bi-directional removal strategy that takes aggressive cuts to remove material quickly.

It’s part of Dynamic Motion technology, a set of toolpath strategies that extend tool life and maximize cutting efficiency while using proprietary algorithms to monitor the stock material and prevent gouges.

After roughing the area, Ohler uses Mastercam’s advanced multi-axis solutions including Flow 5-axis for semi-finish and finish operations. New to Mastercam 2021, Flow has separate feed rate control options for entry and exit linking moves.

“We semi-finished the shape with a heavier stepover and a looser tolerance – probably about 0.001" tolerance – and a 0.100" stepover, leaving 0.005" on the surfaces. When it came time to finish, we tightened the tolerance to 0.0005" and the stepover to 0.008".”

This strategy created a superior surface finish and eliminated part polishing.

Following multi-axis finishing operations, operators must machine the actual cut edge. Machinists flip the part, mill off the dovetail, and send the part to heat treat before additional cutting.

“Using Dynamic Plane Creation, we tilted the part and roughed-out the cut edge using a 3D raster cut. This allowed us to force the tool to approach the shape at a specific angle while also leaving material for hard milling. Parts can move a bit during the heat-treating process; to ensure accuracy, tight-tolerance parts are machined hard, as are most cut edges,” Ohler explains.

Once a punch form is built and goes into production, it can stamp out multiple parts per minute, depending on size and thickness. These parts are stamped out of thin sheet metal and then welded together to build a strong unibody frame.

McAfee Tool & Die invests heavily in CNC equipment and software to improve capabilities and lower costs.

Repeatability

Part of MTD’s strategy is maintaining a repeatable system for all parts running through the shop. One of the biggest reasons MTD programmers chose Mastercam was because of its flexibility to recreate the code for machining a wide range of parts and its consistency with the final code sent to the machines.

“Since we have this software and the ability to reverse engineer, we can produce all the die components a unibody needs,” Lysiak says.

The McAfee team can receive a part from a customer, reverse engineer it, and produce a cleaner, higher quality part.

“We also create spare components so production lines don’t shut down,” Lysiak notes. “Once in the system, replacements can be made without the need to ship the die to the shop. The cost savings to customers add up quickly.”

Lysiak says that his goal is to reduce lead times while producing the high-quality parts customers expect. He does this by having his team of programmers revise and check programs frequently to ensure the most effective cutting process.

“We always try multiple different techniques and toolpaths to find areas where we can push the envelope,” Ohler explains.

McAfee Tool & Die programmers use Mastercam’s Dynamic Plane Creation tool to rough-machine punch forms, leaving enough material for hard milling.

With more than 62,000 CNC programs on file, all in the latest revision, customers can get replacement parts with confidence, including parts and tooling for overseas customers.

McAfee already has his sights set on the next set of machines for his shop.

“Going forward, we are looking to expand our advanced machining capacity. We plan to purchase a new 5-axis mill, two new CNC mills, one new CNC lathe, add another seat of Mastercam, and hire a few extra employees,” says Gary McAfee, owner of McAfee Tool & Die. “Our commitment to excellence is achieved through c CNC Software Inc. https://www.mastercam.com

ommunication, fulfilling customer needs, and staying ahead of the ever-changing curve in machining technology.”

CNC Software Inc. https://www.mastercam.com

McAfee Tool & Die (MTD) http://mcafeetool.com