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Move over, magnesium, as PBT is used for drill housing

Two parts are combined into one—and a metal die-cast part gets replaced with plastics—as a power tool now entering the market offers another showcase for thermoplastics' potential.

MPW Staff

August 4, 2010

2 Min Read
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Two parts are combined into one—and a metal die-cast part gets replaced with plastics—as a power tool now entering the market offers another showcase for thermoplastics' potential.

The tool, a hammer drill, is made by DeWalt, part of the Stanley Black & Decker corporate group. For this tool, which is being commercialized throughout Europe this month, DeWalt opted for a plastic housing that is a combined part, enclosing both the electric motor and the gear.

The housing, inside the power drill, replaces two separate housings, one of which—the gear housing—used to be made of die-cast magnesium. The new plastic housing now accommodates the electric motor and the gear along with the chain drive; it must be precise enough to ensure that the axes of the gear components are parallel and that they remain so, even at high operating temperatures. DeWalt specified BASF's Ultradur B4300 G6 polybutylene terephthlate (PBT) for the housing, which it injection molds at its facility in the Czech Republic.

Reimund Becht, project manager at DeWalt in Idstein, Germany, commented, "Doing away with an additional metal part simplifies inventory and logistics, while the integration of key functions such as snap-on fastenings eliminates the need for screws and cuts down on assembly time. Moreover, there is no longer a need for cut threads and the cost for parts is reduced since plastic parts are very precise and, in contrast to metal, do not have to be mechanically reworked."

There are other advantages to the new design: Additional electric insulation of the live parts of the motor can also be dispensed with, so that the entire construction becomes more compact. Also, the acoustic damping behavior of the plastic housing is superior to that of metal, and the injection mold lasts longer than the magnesium die-casting mold. —[email protected]

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