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IS 15314 (2003): Method of Tests for Tightness and Balanceof Stitches on Seam Sewn by Industrial Sewing Machines [MED29: Sewing Machines]

IS 15314:2003

Indian Standard

METHOD OF TESTS FOR TIGHTNESS ANDBALANCE OF STITCHES ON SEAM SEWN BY

INDUSTRIAL SEWING MACHINES

ICS 61.080

@ BIS 2003

BUREAU OF IN DIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

March 2003 Price Group 1

Sewing Machines Sectional Committee, ME 29

FOREWORD

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by the”SewingMachines Sectional Committee had been approved by the Mechanical Engineering Division Council.

The standard specifies the method of tests for tightness and balance of stitches on the materials sewn by singleneedle straight lock stitch industrial sewing machines.

This standard is one of the series of standards prepared to rationalize the method of tests for industrial sewingmachine and specifies the procedure for measuring vibrations generated by single needle straight lock stitchindustrial sewing machines and over edge industrial sewing machines as a vibration level and vibrationdisplacements of industrial sewing machines.

“Other standards in this series are:

1S 15312:2002 Method of tests for seam puckering on materials sewn by industrial sewing machines

IS 15313:2002 Method of test for vibration measurement for industrial sewing machines

In preparation of this standard, assistance has been derived from the following standard issued by the JapaneseIndustrial Standard Committee:

JISB 9055:1986 Testing methods for seam purchasing on material sewn by industrial sewing machines

In reporting the results of a test or analysis made in accordance with this standard, if the final value, observedor calculated, is to be rounded off, it shall be done in accordance with IS 2: 1960 ‘Rules for rounding offnumerical values (revised)’.

IS 15314:2003

Indian Standard

METHOD OF TESTS FOR TIGHTNESS ANDBALANCE OF STITCHES ON SEAM SEWN BY

INDUSTRIAL SEWING MACHINES1 SCOPE

This standard specifies the method of tests fortightness and balance of stitches on seam sewn bystraight lock stitch industrial sewing machines(hereafter referred to as the sewing machine).

2 DEFINITIONS

For the purpose of this standard the followingdefinitions shall apply.

2.1 Sewing Machine

The sewing machine means unit set with a sewingmachine head, base/table, legs and drivingarrangement.

2.2 Tightness and Balance of Stitches

The leno state of sewing threads constituting stitchesand the state of tightness and balance of sewing threadsto the sewn materials. This is expressed by the ratio ofsewing threads lengths and rates of tightness andbalances of needle thread and of bobbin thread as wellas of cloth.

2.3 Incidental Looping

The part of knot state of needle thread appearing onthe back surface of sewn matter at the seam.

2.4 Looping

The part of loop state of needle thread appeared on theback surface of sewn matter at the seam.

2.5 Skip Stitch

The condition where a part of stitch is not formed atthe seam.

3 TEST PROCEDURE

3.1 Preparation of Test Piece

Make the size of test specimen 100 mm in width,300 mm in length as shown in Fig. 1 and make one set

by overlapping the required number of sheets.

3.2 Test Method

By taking into consideration the sewing workconditions of following each item, prepare three rowsof seams along the sewn portion of Fig. 1 for the testpiece:

SEWN PORTION

4——t——

.+-- —--+- .- tt 100——

-.— .--— --- —-- +——t

a)

b)

c)

Alldimensions in millimetres,

FIG.1 TEST PIECE

The installation of sewing machine is so stabi-lized that the vibration does not give inter-ference to sewing.The running of sewing machine is to be soperformed as to become the specified numberof revolution quickly from the stopping condi-tion.The test piece is to be so made that excess forceis not.added from the outside and, sewn fromits front end up to rear end.

3.3 Method of Measurements

3.3;1 Measurement of Thickness of Test Piece

Measure the thickness (mm) of test pieces of one setspecified in 3.1 at five portions; and obtain the averagevalue (to two places of decimals).

3.3.2 Measurement of Needle Thread Length andBobbin Thread Length

a) Place a test piece after sewing as described in3.2 on a flat stand, under natural condition asit is in the sampling section shown in Fig. 1,mark at interval of 50 mm on each row so asnot to come on needle hole, thereafter cut thepart and prepare the sample of three piecesshown in Fig. 2.

IS 15314:2003

SLAM 20 Approx.

i ———— ———-

b)c)

d)

Alldimensions in millimetres.

FIG.2 SAMPLE

At the time the seam is to be free from inciden-tal looping, looping skip stitch, etc.Count the number of stitch in the sample.In order to make loosening of thread easy, cutdown near the sewn portion of sample withtaking care so as not to damage the sewingthread, and take out the needle thread andbobbin thread from the sample without apply-ing undue force.Press lightly the needle thread and bobbinthread in such degree that the thread is notelongated and becomes straight and measuretheir lengths (mm) by using a scale of accuracyof 1 mm.

3.4 Method of Calculation

3.4.1 The ratio of sewing thread lengths shall becalculated accord]ng to the following formula and theaverage of three pieces of sample shall be obtained (tothe integer place):

~=~xlm

I!&

where

a = ratio of sewing thread lengths (70);

L, = length of needle thread, mm; and

Lb = length of bobbin thread, mm.

3.4.2 Tightness rates of needle thread, bobbin threadand cloth shall “be calculated according to thefollowing formulae and the average value of threepieces of sample, be obtained (to the integer place):

where

s ——

N=

T=

B. =p, =

B. =

sewing length, mm;

number of stitches;

thickness of test piece of one set, mm;

tightness rate of needle thread (%);

tightness rate of bobbin thread (Ye); and

tightness rate of cloth (%).

4 RECORD OF TEST RESULTS

For test results of tightness .of stitches, (a) to (d) shallbe recorded and, as required, (e) be recorded.

a)

b)c)d)

e)

Tightness of stitches:i) Ratio of sewing thread lengths,

ii) Tightness rate of needle thread and bob-bin thread, and

iii) Tightness rate of cloth.Date of testClass and type of sewing machine used for testMaterials:

i) Classification of material used for testpiece (as required, the sample is to beappended); and

ii) Classification of sewing thread.Test conditions:

i)

ii)

iii)

iv)

v)vi)

vii)

viii)ix)

Overlapping method of test pieces (sur-face, back face, directions and numberof sheets);Average value of numbers of needles ofthree pieces of sample;Number of revolutions of sewingmachine;Thread tensile force of needle thread andbobbin thread, T (see Note 1);Check spring tension, F (see Note 2);Class of needle and number of needle(thickness number of needle stem);Dimensions of needle hole of throatplate;Class of presser foot; andPresser foot force, kg.

1 The thread tensile force means the tensile force to rake outupward the threadby hanging on thread guard bend bar from thestitch balancing thread tension dish at the stopping time ofsewing machine. The thread tensile force of bobbin threadmeans the tensile force to take out upward in this inclination thethread from needle hole of throat plate at the stopping time ofsewing machine.

Further, in order to make the bobbin thread not to contact therotating hook, measure under the condition where the needle baris at nearly upper dead point.

2 The check spring tension means the tensile force whenhanging the needle thread on check spring and thread guard bendbar, and pulling upward and then the check spring begins thedisplacement.

2

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Enquiries relating to copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed

periodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of‘BIS Catalogue’ and ‘Standards: Monthly Additions’.

This Indian Standard has been developed from Doc : No. ME 29A-M 18( 0438).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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