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Crawfords wide range Multibore
Collet system was designed to overcome the limitations
imposed by conventional Spring Collets.
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The Multibore
Collets are generally accepted in the machine tool industry
as a standard part, having been developed in close collaboration
with leading machine tool manufacturers. Our Multibore
Collet systems are standard equipment on machine tools
worldwide.
The
range includes all European standard DIN 6343 Auto Multibore
Collet types.
Multibore Collets have a 1/8" gripping range. DIN 6343
Auto Multibore Collets have a 2mm gripping range. The
two types are not interchangeable within the same chuck
configuration.
The
main advantage of Multibore Collets is their ability
to maintain a parallel grip over the entire closure
range. Multibores are not specific to a bar stock or
material size. By holding a minimum inventory of standard
collets, immediate availability of collets can be provided
for non-standard diameter material.
Components
must occupy a minimum of 67% of the collet length (front).
Crawford Multibores are supplied with a plain bore as
standard and can alternatively be supplied in the "Heavy
Duty" configuration for holding black bar or for operations
involving very heavy machining.
Spring Collets
Spring Collets are used
primarily for second operation work where marking of
the workpiece is to be avoided or where it is necessary
to grip a short portion of the component. The collet
bore diameters are dedicated and are normally finished
to customers requirements, however, standard sizes are
held in stock.
Where the use of a component
backstop is required a simple arrangement may be secured
in place by spiral pins, as the collet tail is soft
enough to permit drilling.
Emergency Collets
Emergency Collets have
a similar function to Spring Collets except that the
bore area is left soft and has only a small pilot hole.
The collets are supplied in the spread condition, complete
with a set of dowel pins. These pins are placed in locating
holes between the collet head segments; the collet is
then clamped. The customer may then machine the collet
bore to suit, then remove the dowels prior to use.
This type of collet is
not intended for volume production where the lack of
bore hardness would constitute a problem. It does, however,
facilitate a fast component turn around where component
diameters cannot be anticipated.
