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.
