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Most
manufacturers realize that they should do something more with the
saturated stringy chips, bar ends, parts and tooling than have a
scrap dealer haul them away. There are very compelling reasons to
reclaim both the metals and the machining fluids – like a
seller’s market for most scrap, and vast savings from coolant
and oil recycling.
There are also many compelling reasons why chips should be
dried at the manufacturing site, including stringent environmental
regulations
that apply to wet chips, ISO 14000, and potential saving in labor,
housekeeping, and transportation expense. Many methods produce dry
chips with a retained moisture of less than 5%. However, not all
methods produce chips that can command the optimal resale
price, or do so without
an additional investment in equipment. This discussion reviews three
possible methods.
The first is the batch spinner, also known as a wringer, slinger
or centrifuge. With this time-proven method, scrap is loaded into
a basket
which is then positioned in the spinner. The basket is spun for a
pre-selected or operator-determined amount of time. At the end of
the cycle, the
basket is removed from the spinner and the drained scrap emptied.
Batch spinners are appropriate for facilities with small or highly
irregular quantities of chips. However, they are not without their
problems. The labor-intensive spinner requires manpower for loading
and unloading the basket and for actuating the process.
A second shortcoming of batch spinners is that they only classify
scrap into two components, fluids which go in one direction and chips
which
go in another. Top dollar on mixed scrap can only be obtained if
the solids are sorted, a process requiring further handling and labor
expense.
Another disadvantage is the variability of spinner cycle time. If
it is operator-selectable, optimal drying may not be achieved.
A second method of obtaining dry chips is the compactor, also referred
to as a pelletizer, pucker or briquetter. The compactor uses hydraulic
pressure to compress the volume of machining saturated chips, removing
fluids in the process. The result is a compact puck or disk of scrap,
ranging from 3.5 to 5 inches in diameter.
Compared to mainstream methods of drying chips, compactors represent
a relatively new approach in the machining industry. One limitation
of compactors is scrap type. Compactors often cannot handle large
parts or bar ends without jamming. Operator education and/or an
investment in a supplemental parts sorter may be required to avoid
equipment jams and breakage.
Available markets and resale price should be evaluated prior to
purchasing a compactor. The process creates pucks that vary by equipment
manufacturer and application. Some scrap buyers prefer pucks. Others
have found they require special handling, diminishing their value.
“Buyers from secondary smelters have explained to us why they
prefer chips dried by our systems,” said William Nemedi, President
of chip processing system manufacturer InterSource, in Kalamazoo,
MI. “Pucks are notorious for entrapped moisture and air. Instead
of sinking in molten liquid, they float. This exposes more metal,
and the more exposed metal, the greater the melt loss.”
A third method for generating dry scrap is an automatic chip processing
system, a process with a proven record of success which combines
components to provide optimal drying for each application’s
specific requirements. Integrated parts separators may be utilized
to classify and pre-size scrap, automatically removing parts, bar
ends and tooling. An integrated shredder reduces any form of scrap,
bird nests, bales or tangles, to a uniform size for feeding to
the wringer. The chip wringer, central to the system, removes fluids
via centrifugal force. Swarf recycling conveyors may also be used.
“Continuous chip processing systems successfully handle all
volumes and types of chips,” continues Nemedi, “We’ve
been bringing innovations to the industry since 1981. The result
is systems that consistently produce dry chips, with unsurpassed
reliability and ease-of-use.”
Manufacturers today have substantial reasons to dry chips at their
point of generation. Batch spinners, compactors and chip processing
systems, when specified and installed by reputable manufacturers,
can all deliver dry chips. However, to realize their full value
with minimum cost, a continuous chip processing system remains
the most reliable, efficient method for the majority of machining
applications.
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