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Hi,
what type of a sensor can I use to measure the strength of sewing thread...!!
I need to measure the force required to break sewing threads of different types (cotton, nylon, silk etc tc)
I would think a simple force gauge would do. Mount it on a rod and put a plate on the other side then use the thread to pull the plate in the direction of the rod.
the output has to recorded electronically hence weights not an option. Has to be a force guage or some kind of a strain guage which can measure the PULL force..!!!!!
the space is limited so I have to put on the thinking cap for the mechanical fixture part!. Any suggestions about some product numbers to get me started!!!!!
You want a load cell desined for measuring tension. You want to slowly apply tension to your thread while recording the output of the load cell. You want a load cell that is designed for the range of where your assorted threads will break. For example if the strongest thread will break around 40 Lbs of tension you would want a 50 Lb load cell. You may want to see what Honeywell Sensotec has to offer. Also much of this depends on the budget and if it is to be a permanent test fixtre in a commercial application.
For a typical example look at the Sensotec Model 31 as can be found here. Check the data sheets for the low, mid and high ranges. The load cell output would go to a signal conditioner and then to a paperless chart recorder to chart the tension data till the thread breaks.
Thank you ron, you have got me started on the right footing, the poduct is not a commercial fixture. will keep you posted on the solution that comeup with eventually!
I would make a series mechanical linkage consisting of the load cell, the thread under test, an extension coil spring, and a DC motor driving a leadscrew.
The motor runs forward, stretching the coil spring (and thread) to the breaking point. By Hook's law, the tension in the thread will increase linearly as the spring is stretched... Connect the output of the load cell to a data acquisition system and plot the load vs time.
Yeah, a low RPM motor (gear reduced) with a leadscrew was my thoughts as to moving a table. This also can get into some interesting things. For example if I stretch hemp rope till it breaks it will sort of snap while nylon rope will stretch considerably before it snaps.
Interestingly, i was talking to a friend about a related topic recently regarding the *true* strength of fishing line. If you do a search on fishing line strength you might find some interesting stuff there too.
Commercial sewing threads are made to federal strength standards. These are published and used in the textile industry. For certain industries the strengths are critical, for example, the parachute industry. Use Google to locate these data sources.
Commercial sewing threads are made to federal strength standards. These are published and used in the textile industry. For certain industries the strengths are critical, for example, the parachute industry. Use Google to locate these data sources.
I never dreamed and then too, I never thought much about parachutes either.
I started with ASTM D204 - 02(2010)e1 Standard Test Methods for Sewing Threads which can in part be found here and then muddled along to broken link removed ASTM D76 - 99(2005) Standard Specification for Tensile Testing Machines for Textiles. all this stuff.
I now figure that for $10K we can start with a simple machine.
Seriously, thanks for the enlightenment as I had no clue there were ASTIM standards for the testing of tensile strength of sewing thread.
lots of useful information as always.. the project involves investigating why does the thread break in an embroidry machine. is it due to inferior quality threads or the forces exceeding the thread tensile parameters.. something else that cropped up during the discussions was the ability to measure the friction coefficient of the thread through the needle eye... hmmmm..... while I fathom the depth of information regarding the thread failure forces the project supervisor decides that he might have another reason of thread failure. So I have to come up with a way to measure the friction co-efficient as well.... what joy!!!!!! And the needle moves at just over 2500 stitches per min. ......................
@Gary B.. I knew I was sweeping something under the carpet that might come back to bite me..... silk and cotton threads not affected by heat, nylon and polymer based threads yes... now what happens to the the needle itself!! I will have to check. Will take some manual temp readings of the needles after long continous runs... There is an airjet directed at the needle eye (hopefully that would take the heat out of the equation) but I will still take those readings
Not just the needle but the tensioner and anyplace else along the feed path that the thread could be rubbing against. A little heat here, a little heat there, and in the end it all adds up. For instance, if the thread is warmed by its feed path the force of the needle plunging through the cloth could break the thread not because of the temperature of the needle but, because of the heat generated by rubbing against the fabric already warmed by the previous stitches.
In high speed commercial sewing machines speeds can approach 5000 stitches per minute. The movement of the thread through the needle can heat the needle to the point it loses its temper. This is why lubricant or blowing are used for cooling. This according to a trade publication.
On a lock stitch machine, a machine with a bobbin, The thread must pass around the bobbin to make a stitch. When the takeup arm drops to allow this to occur, as much as 8 inches of thread will pass down through the needle eye. This same thread must pass back up through the needle eye, less the amount left it the stitch, when the stitch is made. So any point on a length of thread may pass through the needle for 60-80 cycles before it is finally left in a stitch.
On chain stitch machines and sergers this doesn't occur so thread quality is less important.
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