Automatic crimp contraction- and shrinkage tester for yarns

TEXTURMAT ME

Pre-tensioning weights

Heating cabinet

Hot water container

Crimp contraction, crimp modulus and crimp stability are calculated from the measured lengths using the following formulas:

Crimp contraction = [ (lg - lz) / lg ] x 100(%)

Crimp modulus = [ (lg - lf) / lg ] x 100 (%)

Crimp stability = [ (lg - lb) / (lg - lz) ] x 100 (%)

Load (cN/tex)	2	0,01	0,1	10 or 20	0,01
Duration of load	10sec	10min	10sec	10sec	10min
Length of hank	lg	lz	lf		lb
Schematic representation of the crimp contraction test

A similar method is used to determine crimp parameters according to ASTM D 4031.

The crimp contraction testing of textured carpet yarns (BCF), which characteristically have relatively high yarn counts, is a special case. For this application, yarn hanks with only one wrap, i.e. a yarn loop, can be used for testing.

The determination of the yarn shrinkage, due to thermal or hydrothermal treatment, is a further test method for textured yarns and other yarn types, e.g. according to DIN 53 866 or ASTM D 2259. In this instance, testing is usually also carried out on yarn hanks by determining an initial length (length lg1), followed by a thermal treatment and a second length measurement (lg2). Shrinkage is calculated by applying the following formula:

Shrinkage = [ (lg1 - lg2) / lg1 ] x 100 (%)

Likewise, the texturing quality of air-textured yarns is also determined by carrying out tests on yarn hanks. In this case, the proportional length increase of the hank after being subjected to a high tensile force is the measured variable and criterion for the stability of the yarn structure.

The TEXTURMAT ME is a test instrument for fully automatic length measurements on yarn hanks, characterised by its high flexibility in terms of test sequence configuration, choice of measuring loads and time-intervals for the loading- and unloading periods. As a result, it is possible to carry out different testing methods according to different standards, e.g. crimp contraction or shrinkage tests not only on (textured) filament yarns but also on fibre tow.

The TEXTURMAT ME is equipped with a removable 30-position magazine, within which the suspended yarn hanks are pre-loaded with weights. Special magazines are also available for testing BCF yarns.

The application of tensile forces and the measurement of yarn lengths for predetermined load times are program-controlled and are brought about by a loading carriage in combination with a high- resolution force measuring system. The size of the force can be freely selected.

The measured values, e.g. crimp contraction, crimp modulus and crimp stability according to DIN 53840, are automatically determined and are, together with the statistical characteristics, evaluated by a the TESTCONTROL PC system.

In general, it is recommended to operate the TEXTURMAT ME with several magazines. In addition to the magazine already in use in the test instrument, others can be prepared, i.e. loaded with hanks or heat treated to ensure a continuous test cycle.

A heating cabinet with the appropriate inner dimensions to accommodate the TEXTURMAT magazine loaded with hanks is available as a TEXTURMAT ME accessory. The control range of the heating cabinet enables a full range of temperature settings necessary for crimp development and the inducement of shrinkage.

Especially for hot-air shrinkage tests with relatively high temperatures it is essential that, after opening the heating cabinet and inserting the TEXTURMAT magazine, the selected temperature is achieved within 30 sec., as specified in the DIN 53866 standard. For this application a special version of the heating cabinet with a computer controlled heating system is available.

Testing methods

Technical data

TEXTURMAT ME, basic equipment

Sample holder:

Magazine with 30 positions, pre-tensioning weight of 2.5 cN for each individual position

Loading equipment:

Vertically moving carriage with loading fork, programme-controlled rate of load application, max. loading speed 8000 mm/min, electronic travel measurement of the loading carriage via resolver, resolution 1 µm, max. load 55 N (higher loads on request)

Force measuring instrument:

Modified electronic precision scale, resolution 0.1 cN

Additional equipment

Heating cabinet:

Model TKL, cabinet shaped, for accommodating one TEXTURMAT magazine, temperature range 30-300 °C

Optional: Model TKL CC with computer controlled heating

Hot water container:

Model WKH 2, cabinet shaped, for accommodating one TEXTURMAT magazine, loading from above using a crane and electrically operated chain hoist, temperature range 40-100 °C

Further technical data

Mains supply:

TEXTURMAT ME:

230 V, 50 (60) Hz

current requirement approx. 1 A

Heating cabinet:

380 - 400 V three phase current, 50 (60) Hz

current requirement approx. 18 A

Hot water container:

380 - 400 V three phase current, 50 (60) Hz;

current requirement approx. 30 A

Compressed air supply:

5 bar, 10 l/min.

Dimensions:

TEXTURMAT ME:

Height 1670, Width 600, Depth 600 mm, Weight approx. 200 kg

Heating cabinet:

Height 1373, Width 856, Depth 732 mm, Weight approx. 120 kg

Hot water container:

Height 1085/2455, Width 890, Depth 750 mm, Weight approx. 180 kg

The above technical contents can be subject to changes by Textechno.