Product category:
Honing, polishing, burnishing and lapping
News Release from: Engis (UK) | Subject: Single-pass bore finishing
Edited by the Manufacturingtalk Editorial
Team on 24 October 2005
Single-pass bore finishing cuts tools'
cost
Single-pass bore finishing is performed with pre-set barrel-shaped tools that pass once through the bore while the tool, part, or both rotate - tool cost is reduced by over 50%.
Tight tolerances are extremely important in gear manufacturing - even more so when those gears are used in performance motorcycle transmissions Just as important is the ability to manufacture as competitively as possible
This article was originally published on Manufacturingtalk on 13 May 2004 at 8.00am (UK)
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Single-pass bore finishing applications broaden
From being a process only applicable in finishing of CI through bores, single-pass bore finishing can now be applied on blind bores, through bores, stepped bores and in many different materials.
Flexible cell speeds up honing throughput
A robotised Engis finishing cell, installed at E2A, replaces manually operated honing practice to finish Landrover Discovery centre housings.
This was the position an American motorcycle component manufacturer faced recently when it contacted Engis Corporation about single-pass bore finishing.
"The first alternative the company considered was installing a number of conventional honing machines, where multiple passes of an expanding mandrel achieves a precision finish," explains Robert Marvin, Engis product manager.
"But the company also had to be as cost-competitive as possible in producing these parts, which led to our discussing single-pass bore finishing." The specification requirements for the motorcycle component supplier included removing 0.050mm of material from a 20mm gear made of hardened steel (HRC 58-64).
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Bore tolerance was 0.015mm, the finish requirement was 0.8 micron Ra, and cylindricity needed to be held to 0.008mm.
Conventional honing uses a hone that reciprocates many times while expanding and contacting the cutting stones during each cycle.
By comparison, single-pass bore finishing on an Engis SPM-series machine is performed with pre-set barrel-shaped tools that pass once through the bore while the tool, part, or both rotate.
Tooling on the Engis machine also features a proprietary slow-wearing diamond coating that together with the single-pass system can achieve bore-finishing tolerances within 0.000020in in a single finishing cycle.
For the motorcycle component supplier, actual bore tolerance achieved was 0.007mm, 0.6 micron Ra finish, and 0.005mm cylindricity.
With two single-pass Engis SPM machines, each configured with six spindles capable of finishing two parts at a time, the motorcycle components supplier is producing 14,000 gears/day.
Where conventional honing machines would require taking the machine out of service every 2,000 pieces to change tooling, the slow-wearing superabrasive diamond coating can routinely finish more than 60,000 parts, even in hardened steel.
And since the tooling finishes the full periphery of the bore, interruptions such as keyways or splines do not affect performance.
"The result is much more machine uptime and a tool cost reduction of more than 50% while providing the precision finish these gears require," Marvin explains.
"Total perishable tooling costs are approximately one cent per finished gear.".
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