Metallic card Clothing - Page 3
GRINDING A CUT-TO-POINT CYLINDER WIRE:
Wire points of cylinder have become finer and the tip is cut-to-point.Because of this new profile,
it has beccome necessary to recommend a little or no grinding of the cylinder wire following mounting.
TSG grinding machine of GRAF(wire manufacturer) can be used to sharpen these modern wires.
TSG grinding is a safe method of grinding.
Picture1. BARE CYLINDER GRINDER
Before grinding , the wire should be inspected with a protable microscope to ascertain the wear. Based on this and the wire point land width, no of traverse for TSG grinding should be decided. If the width of
the wire point tip is bigger and the wear out is more, the number of traverse during grinding should be more. For a new wire, 3 or 4 traverses may be enough. But it may require 10 to 30 traverses for the last grinding before changing the wire, depending upon the maintenance of the wire.
GRINDING A NORMAL CYLINDER AND DOFFER WIRE:
The first grinding of the metallic wire on the cylinder and doffer is the final and most important step leading up to providing the card with a cylinder in the best possible condition for carding well at maximum produciton rate.Grinding the lands of the teeth provides the leading edge of each tooth with the final sharpness reqauired for maximum carding power.
The first grinding should be allowed to continue until at least eighty percent(for cylinder) and 100% (for doffer) of the lands of the teeth have been ground sufficient to sharpen the leading edge of the tooth.
To ascertain this stage of grinding, it is necessary to stop the cylinder regularly and use a simple
microscope to examine the teeth at random across and round the cylinder.
If the wire on the cylinder is of good quality and has been correctly mounted, the initial grinding
period should be completed with in 20 min.
It is essential to avoid over-working the wire before taking corrective action. The regrinding cycle
must be determined accurately for the conditions applying in the individual mill, by using the microscope.
If regrinding is done properly, there are several advantages
carding quality will remain consistent
There is no risk of overworking the wire
Time required for regrinding is very short
The exact condition of the clothing is known
The working life of the wire is likely to be longer because the points are never allowed to become worn
To obtain acceptable grinding conditions at the low grinding speed, the grindstone must always be
SHARP, CLEAN and CONCENTRIC. If the grinding stone is gradually allowed to become dull and glazed
through constant use, the limited cutting action available will eventually disappear, resulting in burning
and hooking of the carding teeth.
Due to the low peripheral speed of the grindstone which has to be used, it is most important that the
speed of the wire to be ground is as high as is practicable to provide a high relative speed between
the grindstone surface and the cardig teeth.If wire speed is low, the individual carding tooth spends too
long a time in passing under the grindstone, thereby increasing the risk of hooking and burning the tooth, which is usually irreparable.
With cylinder grinding, speed is no problem because the normal operating speed of the cylinder is more
than sufficient. The speed of the doffer for grinding is more commonly a problem and this should be driven at a minimum speed of 250 m/min, to avoid damage when grinding the wire, the design which is particularly susceptible to hooking due to the long fine, low angled teeth needed on the doffer.
The directions of rotation for metallic wire grinding are normally arranged so that the back edge
of the tooth is first to pass u nder the grindstone. This is termed grinding "back of point"
Flat end Milling Machine
Multi roller Mounting machine
GRINDING FLAT TOPS:
Flat tops provide the opposing carding force against the cylinder wire and hence can equally effect
carding quality.It is essential to ensure that the tops are kept in good condition to maintain maximum
carding power with the cylinder.Again, the only reliable approach is to examine the tops with the
microscope and decide whether grinding is required or not.
For cards fitted with regrindable tops, it is good practice to regrind the flats at regular intervals
thus ensuring that the conditions of the two principal carding surfaces are always complementary one to other.
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