Page 17 - MMI_MarApr 2021 (high-singles)

INSIGHT

HONING SKILLS THAT MATTER

A leading honing equipment manufacturer answers a few common FAQs on
honing, a process which is typically performed to bring bores to a precise size or
achieve a specific surface finish.

Source: Sunnen

According to Sunnen, honing is typically required to achieve bore diameter tolerances of ±0.0002 inch or tighter with high-quality surface finishes.

A s one of the most EDM is even more precise, pro- es of ±0.0002 inch or tighter with
common machining ducing a bore diameter within high-quality surface finishes.
operations, holemak- ±0.0005 inch. Honing is a sizing and finishing
However, there are good reasons operation in which a revolving
ing presents manufacturers with to turn to honing for applications tool (mandrel), fitted with abra-
with the most stringent require- sives, strokes in and out of a bore.
plenty of options. Depending on ments for surface finish and pre- During the process, the abrasives
cision. According to Sunnen, a are expanded, removing minute
bore diameter and surface finish manufacturer of honing equip- amounts of material to bring the
ment that provided the informa- hole to its proper size and finish.
tolerance, a shop might choose tion for this article, EDMed holes The resulting finish consists of
typically require further pro- microscopic peaks and valleys
drilling, milling, electrical dis- cessing to smooth surfaces. The arranged in a crisscross or ‘cross-
process is relatively slow as well. hatch’ pattern. The valleys allow
charge machining (EDM) or a Optimized milling processes fol- oil retention between mating com-
lowed by boring, or reaming may ponents during operation, such as
combination of those CNC ma- produce high-quality results, but pistons within an engine cylinder.
not always consistently. Honing Although the process has been
chining processes and achieve achieves all three goals: that is, the performed for many years, hon-
process consistently and reliably ing technology has evolved, and
DEREK KORN quality results. For example, the achieves bore diameter toleranc- some manufacturers still have
Editor-in-Chief
Production Machining hole created by a 0.5-inch drill
dkorn@
productionmachining.com might range from ±0.002 inch or

be as much as 0.006-inch over-

sized, but a subsequent reaming

operation can produce a smooth-

er surface finish and a hole diam-

eter within ±0.0002 inch. Ream-

ing or boring milled holes can

achieve similar results, while

www.mmindia.co.in | 17March-April 2021