CNC machinists at Mar-Lee Companies use Emuge end mills to mill hard materials.

For more than 30 years, Mar-Lee Mold Company Inc. (http://www.marleecompanies.com/index.php) of Leominster, Mass. focused on basic core and cavity mold work for high-end, one-off custom mold making jobs.

One-off jobs demand that Mar-Lee use the right end mill the first time so it can make its molds in automated production with minimal hand labor.

Like other savvy moldmakers, Mar-Lee has moved toward zerostock machining, which requires the correct tooling, machine tool and software to produce cores and cavities without leaving extra stock. The technique eliminates manual labor operations such as hand finishing, polishing and fitting, and reduces cycle time while improving accuracy and surface finish.

“For Mar-Lee to remain competitive in a shrinking moldmaking market, we needed to create efficiencies wherever possible,” John Gravelle, president of Mar-Lee Companies, said.

High-speed machining presented opportunities to create efficiencies, but also presented challenges. Because feeds and speeds were different for high-speed machining versus conventional CNC machining, different end mills were required. Also, Mar-Lee began its high-speed machining operations on graphite material and then broadened its capabilities to include machining steel. Milling a harder material added to its challenges.

Emuge Corp. (www.emuge.com) suggested that the company use end mills with special geometries and coatings to provide dependable production with increased productivity and reduced costs.

Much of the work that Mar-Lee does to make molds for injection molding involves short runs in hard material on high-speed machines.

The company reports that Emuge end mills provide it with nearly 40 percent more tool life than others.

“During the process of a cycle, from toolholder to machine to the end mill, there is a notable, to 50 percent, cycle time reduction using Emuge end mills,” Mark T. Lavoie, purchasing manager at Mar-Lee, said.

Emuge end mills help Mar-Lee to reduce labor costs by allowing one operator to tend three automated work cells. The company is able to conduct several hours of unattended operation using such efficient work cells.

“My machine runs all night using the Emuge end mill, many times working in hardness of 48 to 56 Rc, and by morning the cutter is still good,” Scott Hastings, CNC machinist at Mar-Lee, said.

“We can’t do that with other end mills because we would have to set-up four tools and break up the tool program. Retooling wastes time and money. When you need to take a few tenths off a mold, an Emuge end mill will do it to tolerance. It consistently removes those tenths without wear,” Hastings added.

Carbide Boring Tools Criterion Machine Works (www.criterionmachineworks.com) has introduced a 0.125-in. diameter, solid carbide qualified length (QL) boring tool to its line of solid carbide boring tools. These tools feature a repeatable Z-length of ±0.001 in. from a nominal set length. The company said the qualified length tool’s close tolerance length minimizes machine downtime when changing a tool during a production run. The tools have a closely held locating angle to insure Z- length repeatability. The locating angle also locates the cutting edge on center for long tool life also reducing machine downtime. Seventeen different bore diameter and length configurations are available with the new boring tools. Minimum bore diameters range from 0.050 in. to 0.110 in. The tools bore holes to a depth of 0.700 in. depending on the bore diameter. The qualified length tools must be held in a Criterion qualified length toolholder. Toolholders are available with shanks of 0.125 in., 0.375 in., 0.500 in., 0.625 in. and 0.750 in., and are designed for use in Criterion’s precision boring heads.

Toolholder Fixture Techniks Inc. (www.techniksusa.com) has introduced a toolholding fixture that mounts to the side of a tool cart or bench and secures toolholders for changing cutting tools, collets, and pull studs. The NT S Tightening Fixture is designed to work with: CAT , BT, ISO, and HSK toolholders. Toolholders are placed in the NTS fixture and the locking screw knob is tightened to engage the drive slot or wrench flats – depending on the toolholder – to secure the toolholder. Techniks recommends using a torque wrench and tightening to specifications to insure safety and improve cutting tool life.