How to Buy Used-Sawing-Equipment-Machinery
how to buy used-sawing-Equipment
The principal parts on a circular saw machine are:Saws and filing machines execute the most basic of all
metalworking procedures, the cutting of bar stock to proper
lengths for machining. It is done in the simplest of ways,
substituting mechanically or hydraulically powered motion for
hand or arm motion. Saws used on powered sawing machines are
made as thin as possible in order to be consistent with tool
strength and rigidness. The width of a cut will be close to the
width of the saw, this allows the individual teeth of the saw to
deepen the cut made by each preceding tooth as it moves
through what’s being cut. Straight or curved cuts can be
achieved by controlling the direction of feed.
Bed-the foundation of the machine, provides strength.
Speed change hand wheel-performs speed changes through
selective gearing, pickoff gears or sheave changes.
Power vertical & Power horizontal clamp- saw blade to be
fed into the work.
Automatic bar feed-feeds work in and out of the machine,
smaller-sized machines furnished with auto bar feeds.
Feed control-may be mechanical or hydraulic or a combination
Stock stop-provides for positive positioning of the work.
Saw head unit-the main drive mechanism. Wide-face, closely
fitted, ruggedly supported spiral or herringbone gearing is
generally used for the final drive to worms and wormgears may
also be used for the input drive to eliminate chatter.
The principal parts on a vertical band saw are:
Base-a box-like casting housing the main drive unit, speed
control mechanism and gear shift. Head Assembly-
accommodates the upper band wheel assembly, job selector
mechanism, speed indicator gauge and the band tension
indicator. Tension adjustment-changes the distance between
the two wheels carrying the band. Tension on the band makes it
more rigid comparable to the more heavier tools. Table-
supports the work as it’s fed into the blade. Chip blower-an air
system that removes chips from the cutting areas. Blade shear,
welder & grinder-these are provided so the machine can
perform internal cutting of shapes.
Types of sawing machines
There are 3 basic types of sawing machines: the power hack
saw, the circular saw & the continuous blade band saw.
The power hack saws are depicted by the reciprocating motion
of the blade as it cuts. The cutting takes place in only one
direction and the saw becomes idle on the return stroke. Hack
saws basically follow the same setup: a base and table support
the work which is held stationary while sawing, and a C-frame
that runs the saw blade. Hydraulic or mechanical drives with
speed selection are employed, and three different types of feeds
are used. The weight of the C-frame itself maintains pressure
that feeds the saw into the cut in gravity feeding. In mechanical
friction or hydraulic pressure feeding, the saw is forced into the
cut for faster cutting. In a ratchet mechanism, feed may be
executed by means of a screw or pawl. Since the stroke is
intermittent, hack saws do not have a very fast method of
cutting off stock. Their advantage, though, is they are simple in
design, easily interchangeable from job to job, and relatively
inexpensive to operate and maintain. Hack saws are also
available in a wide range of models and sizes, ranging anywhere
from manual clamping of a single cut to the more complex
The circular sawing machine functions on a milling principle,
however unlike conventional milling machines, the diameter of
the spindle gear will be smaller than that of the saw blade. This
requires careful design characteristics implemented into the
machine to guarantee a smooth, powerful drive to the blade
without hardly any backlash. That is why wide-face, closely
fitted spiral or herringbone gears are used for the final drive,
and hourglass worms and wormgears are often used for the
input drive to eliminate chatter. Circular sawing machines are
distinguished by a round or circular saw blade that is mounted
on a power-driven arbor and rotated through the cut. These
machines are divided into 3 types: the cold saw, abrasive cutoff
machine and the friction saw. Cold saws are the most sturdy
and powerful of the saws. Their direct geared drive allows the
application of increased cutting speeds, lending itself well to
automation and to combine with other machining units. Friction
saws operate at high speeds and develop intense frictional heat
when coupled with heavy feed pressures and actually melt or
burn the metal away as it touches the blade. Teeth, if supplied,
serve mainly to carry oxygen into the cut.
Band saws apply a very thin continuous steel loop with
hundreds of cutting teeth on one edge. The band is carried on
the rims of two or three wheels, one of which is powered by the
drive. Friction is created between the band and the wheel
prevents slippage. Adjusting of the tension on the band is
possible, it gives the band saw a rigidness comparable to that of
much heavier tools. There are two basic types of band saw:
vertical and horizontal. The vertical saw has one wheel located
above the other and a horizontal work table where the band
passes. It is commonly recommended for contour sawing,
notching, slotting, splitting, serrating and other cutoff
operations. The horizontal saw has both wheels in line, so not
much additional machining, if any, is required.
While demand for standard controlled bandsaws holds steady,
demand for CNC production bandsaws are on the rise. For CNC
bandsaws, operators are able to enter the number and length of
parts into the CNC and go to other work as the saw cuts the
material unattended. This increase in sawing time is also
causing a shift in blade requirements. Operators now need
blades that last longer to make unattended sawing more
productive. Although a blade on modern saws only require two
or three minutes to change, the cost of the blade and time to
change it add up. Any prolonging of the chipmaking time in
between blade changing lowers the cost per cut.
When selecting a saw it is important to consider the proper size
and capacity for efficient production. For example, selecting the
right cutoff machine can result in significant cost reductions by
eliminating waste, and reducing machining time and labor
costs. The capacity of hack or band saws is designated by the
maximum square section that can be accommodated by the
machine. Standard cutoff saw capacities range from anywhere
from 6″x6″ up until 24″x24″. Band saw size is designated by
throat clearance, the distance between the cutting blade and the
rear column which supports the upper band wheel. Standard
sizes range from 16″ to 60″. The size of a circular saw machine
is made by the diameter of the circular blade for which the
machine is designed. Sizes range from 10″ to 120″.
Vertical & horizontal band saws_used-sawing-Equipment
When selecting a vertical or horizontal band saw, you must
consider the specific advantages of each machine. User
production requirements will then determine which of the two
machines is more suitable for your needs. The vertical band saw
is recommended for shaping work, simply because it can
remove unwanted material both inside and outside. Since the
cutting force is uniform on the vertical band machine, clamps
and other fixtures are usually not required. However, machining
time is low, the downward cutting force is a slicing action,
therefore is best used when soft, spongy or honeycomb
materials need to be cut without distortion. Vertical band saws
come in a range of sizes from small tool room machines to large
production models. Throat depths range from 16″ to 60″ with
band speeds from 35 to 15,000 sfpm and the horsepower from
I to 15. The horizontal band saw is recommended when speed,
high accuracy, low scrap losses and versatility are special
priorities in the cutoff operation.
- l. Check machine’s bed and structure support components for
cracks, breaks or welded repairs. Breaks, even if repaired, can
affect the machine’s ability to turn out precision work.
- 2. Look in gear boxes and confirm the gears are not chipped or
worn down. Worn or faulty gears can cause slippage in the drive
and feed mechanisms.
- Check all ways and slides for signs of excessive wear. Also,
check the machine’s table and saw arm.
Under-power inspection used-sawing-Equipment
- Listen carefully to all gear boxes while machine is running.
Proper coordinating of gears is important for chatter-free work.
2. Look for backlash in the saw blade, minimum backlash is
evident that the drive blade is smooth and rigid.
- 3. Check the clamping mechanism, make sure it works properly
for accurate cutting.
- Make sure the stock stops operate as they should.
- Verify the lift roller mechanism is working properly so that
work may be easily moved in and out of the machin
- Check the automatic bar feeder.
- Examine the chip clearance system and see that it functions
- On a power hack saw, see that the force feed and quick return
mechanism are properly working.
- 9. For hydraulic equipment, look for leaks, noisy valves and
- 10. Run the machine through its complete cycl See that all
feed and speed controls and electrical controls function
It. Make sure the variable speed adjustment on hydraulic
machines are working and that the speeds are adjusted correctly.
12. After running some work, check the smoothness and
uniformity of the finished workpiece and determine if the
machine fits your needs.