G.H. Tool & Mold
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Auto Castings Fuel Shop’s High-Performance<br />
Machining<br />
The lighter automobiles become, the heavier the workload<br />
gets at G. H. <strong>Tool</strong> & <strong>Mold</strong>. The Washington, Mo., business<br />
specializes in aluminum die cast molds, serving practically<br />
all the major automakers. And as those companies continue<br />
to reduce the weight of cars in efforts to lower emissions and<br />
conserve fuel, they do so by incorporating more die cast components<br />
as opposed to stamped ones.<br />
Automotive work makes up over 90 percent of G. H. <strong>Tool</strong> &<br />
<strong>Mold</strong>’s output, and in the past, the 150-person shop produced<br />
molds mostly for housing-type parts for power transfer<br />
components, valve bodies, alternators and others. But over<br />
the past couple of years, the shop has manufactured an equal<br />
number of molds for structural and suspension components<br />
as well.<br />
The design-to-order company produces complete die cast<br />
molds and replacement parts for existing molds in the field.<br />
Job lot sizes are between one and 10 parts, most of which are<br />
made from a superior grade tool steel. Part machining cycle<br />
times vary anywhere from 30 minutes to eight hours, and<br />
tolerances typically run between +/- 0.0005 to 0.002”. Service<br />
parts for molds usually takes five weeks to finish, while a<br />
complete mold is done in as little as 10 weeks.<br />
To fulfill increased demand from its automotive customers,<br />
G. H. <strong>Tool</strong> & <strong>Mold</strong> relies heavily on Mikron high-speed milling<br />
machines along with a recently acquired Mikron highperformance<br />
5-axis milling machine, all from GF Machining<br />
Solutions (formerly GF AgieCharmilles) and acquired through<br />
distributor Hartwig Inc. in St. Louis. These systems deliver the<br />
speed, accuracy and surface finish capability the shop needs<br />
to produce its high-quality precision molds in the shortest<br />
amount of time possible.<br />
G.H. <strong>Tool</strong> & <strong>Mold</strong> has three Mikron HSM (high-speed machining)<br />
800 milling machines that sport 36,000-rpm spindles and<br />
two HSM 500s with 42,000-rpm spindles. With these 3-axis<br />
machines, the shop takes quick, light cuts using small diameter<br />
cutters at high feedrates to shorten overall part cycle<br />
times.<br />
The newer 5-axis machine is a Mikron HPM (high-performance<br />
machining) 800U-HD (High Dynamics) with a 20,000-<br />
rpm spindle, 60-tool storage capacity and more power for<br />
aggressive cuts – in both roughing and finishing operations.<br />
The machine’s High Dynamics technology delivers 1G machine<br />
acceleration rates, and the machine rapid traverses at 1,771.7<br />
ipm in the X and Y axes and at 1,378 ipm in Z.<br />
The HPM 800U-HD’s Step-Tec HSK A63 in-line spindle generates<br />
63.7 ft-lbs of torque at 4,450 rpm for high metal removal<br />
rates, while also providing the fast spindle speeds necessary<br />
for producing superior part surface finishes. It incorporates<br />
oil-lubricated ceramic hybrid bearings and is vector-controlled,<br />
enabling thread cutting without the use of a compensating<br />
chuck.<br />
According to Danny Straatmann, programming manager at G.<br />
H. <strong>Tool</strong> & <strong>Mold</strong>, the shop does practically all of its really critical<br />
machining on the Mikrons. They are the shop’s “fast movers,”<br />
he said, for lighter smaller components and for both soft<br />
and hard machining – typically around 46-48 Rc. Their speed,<br />
along with accuracy and rigidity, result in far better surface<br />
finishes, and hard machining capability allows G. H. <strong>Tool</strong> &<br />
<strong>Mold</strong> to mill parts to finished size from hardened materials,<br />
thus reducing the amount of die-sinking electrical discharge<br />
machining time required.<br />
The Mikron machines get their extraordinary rigidity from<br />
a special base material, yet they require no foundation. GF<br />
Machining Solutions constructs its monobloc (single-casting)<br />
machine bases from polymer granite that possesses extremely<br />
high vibration-dampening properties, providing strength and<br />
rigidity essential for high-speed, high-performance machining.<br />
Single-casting constructions of the Mikron machines also<br />
ensure machining accuracy and better thermal stability for<br />
excellent workpiece surface quality and minimal tool wear.<br />
Additionally, GF Machining Solutions outfits the machines