-:Crease Recovery Tester:-
OBJECT:-
To determine the crease recovery angle (CRA) of warp and weft direction by
recovery tester.
APPRATUS
REQUIRED:- CRA Tester, forceps
THEORY:-
Crease means when a material is pressurized by some mechanical forces then
there is a mechanical deformation and lines or pleats appear that is known as
crease.
In other words, crease
appears when the material is distorted in such a manner that part of it is stretched
beyond its small power of elastic recovery. For ex. in cotton fabrics the
bending of the fibres which take place during creasing leads to an extension of
the cellulose on the outer surface, and a compression on the inner surface.
After removing the pressure or load and
keeping the sample free from tension, then the maximum angle it forms is called
as crease recovery angle.
PROCEDURE:-
1. Press the
fabric sample (remove all creases present by ironing) then conditioning it.
2. Cut the
specimen in size 40 x 15 mm from the fabric in both warp and weft direction.
3. Then fold 3 samples
face to face and 3 samples back to back as required.
4. Formation of
crease in folded sample by applying a weight of 1 kg up to 5 min, then remove
it safely.
5. Take the
specimen with a forceps and clamp it parallel to the edge of the pointer.
6. Should not
disturb the CRA while clamping and continuously adjust the dial keeping the
edge always parallel for 5 min.
7. Note the angle
parallel to the pointer.
OBSERVATION
AND CALCULATIONS:-
RESULT:-
CRA WEFT WARP
FACE TO FACE
BACK TO BACK
PRECAUTIONS:-
1. Sample should
be in proper dimension.
2. Care must be
taken while handling the creased fabric.
(folded part of fabric ).
3. Keep weight
on the specimen slowly, don’t drop the weight
4. Fabric should
be taken out by using forceps and clamp that limb which is held by forceps.
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