Bar Puller vs Bar Feeder

There are several ways to automate a CNC lathe. That will
depend on your goal for your tooling processes. If you are
working on lengthy stretches of unattended operation, then
a bar feeder is more effective knowing that the design is purposely
meant for longer product designs. In contrary, a bar puller is
a good alternative when we work on small or medium batches
of materials to attain an optimum result for the expenditure. That's
because a puller will cut out the time it takes between bar changes
to enable a single operator to tend multiple machines, measure
critical part features perform value-adding secondary operations.

A bar feeder pushes a bar through a lathe's spindle and into the
workzone. Then a bar puller, installed in a turret station, pulls
the bar out of the spindle. The lathe's turret positions the puller
to grip the bar and then retracts along the Z-axis, bringing the desired
portion of the bar into the workzone. Once turning and part cut-off
are completed on that section, the process will continually repeats
until the bar is totally consumed.

So how do they “grip?” Standard bar pullers use two spring-steel
fingers to provide the gripping force. During setup, the serrated
jaws on the fingers are gapped a bit smaller than bar diameter
(typically 1/8 inch smaller). When the jaws contact the bar, the spring-steel
fingers deflect and expand over the bar. This provides the gripping force for the jaws.
Similarly, heavy-duty models use internal die springs that compress to provide
the gripping force. These pullers typically work with bars that are 3 inches
in diameter and smaller (models with 6 1/2-inch capacity are available).
They are able to grip round, square and hex barstock, and their shanks can
be either round or square to work with various lathe styles.

On the other hand bar feeders are best for longer bar sizes. Then
when we talk on larger production quantities,productivity and
getting the most pieces, logically we assume a 12ft capacity
magazine type bar feeder will fit for the job. From the standpoint of
productivity longer bar feeders will reduce labor cost since
the machine can be left unattended for longer period of time.

There are types of bar feeders that are designed to load and
feed in sizes such as 2-,3- or 4ft long bars. But statistically
smaller types of loaders are rare since longer bar loaders will
help us decide the best fit for the finished products.

To fully exploit the productivity of a CNC bar machine,
it is best to have this products that serves as loaders or
holders automatically for your machines. Such a machine
that loads magazine bars for machining or the one that "grips"
the bar into the set-up.A bar feeder has been developed to
render smaller sizes of bars in addition to its capability.
Seemingly the bar pullers are also entitled to do such task
for the reason that is serves as a guide in machining. To improve
its capability, some pullers has been using coolant for the lathe
to improve the grip in the bars and achieving quality product
performance.

Your run sizes, part diameters, types of materials, accuracy
requirements, ability to run machines unattended,
and a number of like considerations, must determine
the type of bar feeder/puller that is best for your shop.
Each type has unique advantages, and you must weigh both
against your shop’s particular needs. Its up to a machine
shop what type of bar loaders or pullers is best for
their CNC machines to gain maximum profit.