August 2010 eNews

AS CAVITIES DEEPEN AT MOLD Maker, THROUGHPUT DOUBLES WITH 0.001 INCH TOLERANCES

As goes the trend to larger lighting modules in today’s cars, so goes the requirement for deeper cavities in the mold to make them -- and for stiffer machines and tooling to get those deep cavities right.

Nobody knows this better than Jay Noble, lead machinist at Redoe Mold Ltd, Windsor, Canada, a mold maker specializing in automotive lighting molds. “For us, the longer wraparounds for headlights and taillights seen in today’s cars mean that mold cavities are 5-8 inches deeper than they were just five years ago.”

Redoe operator assembles Ingersoll Inno-Fit long reach tool to mill bottom of deep mold cavity. For extra rigidity, coupling features three point contact, self-centering design and large contact area at mating surfaces.

That’s why Redoe last August added an extra-rigid Toshiba boring mill using Ingersoll cutting tools to their equipment portfolio. The new machine also offers a larger work envelope and features laser sensing and a FCS workholding system.

Pleasant Surprise from Tooling

Redoe’s pleasant surprise was that the way they tooled the new mill literally doubled throughput vs. expectations at machine purchase time. To mill hardened stock, they’re routinely feeding at 300-400 IPM vs. an expected 50 IPM with other available cutters. To drill high-aspect holes, penetration speeds are reaching 12-18 IPM, about three times faster than expectations or standard rates.

Redoe is a 100 man mold shop serving automotive OEMs, mainly molds for automotive multicolor exterior lighting, and running 24-7 to maintain 18 week delivery commitments.

“In long-reach milling, chatter is the main enemy; rigidity is indispensible,” says Sean Evers, Ingersoll field rep who works with Noble. “If an unsupported tool starts to chatter at the bottom of a fifteen-inch cavity, a destructive ripple effect sets in. The next thing you know, the operator spends as much time changing inserts as he does making chips. Tool costs rise, throughput suffers and so do delivery schedules.”

At Toshiba purchase time, Noble invited bids from all mainstay tooling providers tentatively selecting Ingersoll based on tooling cost assuming equal throughput. Redoe and Evers tested the extension Inno-Fit doing cavity hogging, cavity finish milling and drilling at the very bottom of 15- to 22- inch cavities.

Results were the same for all the processes, even at extreme removal rates and reaches. All tolerances - -including runout -- held within 0.001 inch. Catastrophic tool or cutter failures simply didn’t happen. “With other extensions, we always had to turn down the feed rate as we went deeper, but not with the Inno-Fit,” said Noble.

Redoe’s current standard choice for milling cutters for roughing out cavities on the new Toshiba is an Ingersoll button cutter. For finishing, especially for straight sides and sharp corners at the bottom, the choice is an Ingersoll Form-MasterV, which treats even thin cuts as axial milling so lateral forces are reduced. In deep cavities this is the key to accuracy. Compared with Redoe’s past experience, these cutters have improved both milling throughput and tool life more than 2 to 1.

All drills on the new Toshiba are the Qwik-Twist replaceable tip drill and the Quad-Drill indexable drill, depending on hole geometry. In holes up to 2 inches diameter and aspect ratios up to 8 to 1 deep inside a cavity, Noble estimates that they are drilling three times faster than before.

Partnership - Redoe’s Jay Noble and Ingersoll’s Sean Evers putting their heads together in shop setting to run a tooling test

The Tooling, Close Up

The Inno-Fit’s rigidity is enabled by a self-centering three point coupling design, large surface contact area at the mating surfaces and an extremely wear resistant material.

Both drills chosen for the Toshiba use indexable cutting surfaces mounted to more ductile steel bodies or shanks. The Qwik-Twist drill features a replaceable carbide tip on an alloy steel shaft. Tips can be changed right in the spindle.

Ingersoll Cutting Tools

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