Re: Crow Foot Fabric
Dear Shri Shekhar Dey,
I have not come across “crow foot fabric” which possibly is a special brand name.
Possibly following information may be of some use to you :
1) Plain weave has crisscrossing (interwoven) singular yarn.
2) Plain weave by paired yarn has crisscrossing (interwoven) yarn in pair.
3) Straight warp weft weave
4) Solid woven ply (uniply) belt i.e. plies are interwoven.
The belt mentioned by you may be in any of the above category. If it is solid woven ply, it will be free from ply separation. Uniply belt has better impact resistance, and is superior and expensive.
An article by H P Lachmann, Germany in “Conveyor Belt Technology” provides very good information about various belts.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 5882916 ■
Re: Crow Foot Fabric
Crow's Foot Weave
Crows foot weave is commonly used to describe a 2x2 broken twill fabric weave which has each warp (longitudinal) thread passing over/under two weft (transverse) threads at a time.
Ajacent warp threads are alternately arranged in twill pattern - sharing a weft thread, and plain pattern (not sharing).
There are a couple of reasons why this weave pattern is used:
-for some higher strength fabrics, over 300kN/m, it helps the weaving and making a more stable fabric.
-with the appropriate warp yarn combined wth a heavy weft yarn, a fabric with outstanding resistance to ripping and tearing can be produced.
"Crow's Foot Weave" has become synonomous with Rip-Resistance here because of association with rip-resistant weaves that we have produced. This is based on the assumption that a 2x2 broken twill weave automatically implies rip-resistance which is not necessarily the case. A heavy weft with the correct warp must be used - typically producing a weft fabric tensile strength of 160+kN/m. We have tested a number of belts with "Crows Foot Weave" fabrics that offer no performance advantage over a standard plain weave.
As stated above, rip and tear strength can be outstanding with the right design, but at the same time impact resistance may not benefit because of the "anvil" effect when the warp threads pass such heavy weft threads. (We have found a double weave with heavy skims very effective for impact).
Similarly fastener holding can also be improved with a crow's foot weave with a heavy weft.
Straight warp fabrics with reduced plies can provide these benefits but the splicing is more difficult.
I hope this is helpful.
regards,
Ray Latchford ■
Re: Crow Foot Fabric
Dear Mr Ray Latchford,
Thank you very much for your valued opinion. There are some fabric available for the same crow foot at tiwan please let me whether you have any idea about this.
Is it possible for you to confirm me the GSM of each type of PN 340.375 400 450 etc along with warp & weft braking strength
of the individual fabric.
Do you think this CRF fabric can be used a breaker fabric on the top of steel cord belt as rip resistant breaker since you said it has a rip resistant properties .
The way you expained that BROKEN TWIL fabric is basically called as CRF .Please let me is there any normal CRF fabriv also available apert from 2x2broken twil fabric.
Regards
Shekhar kumar dey
Sr general manager (Marketting)
TEGA INDUSTRIES LTD
P40b NEW ALIPORE
KOLKATA 700092
Tel 00913324783515
Fax 00913324783820
Email shekhar@tegaindustries.com ■
Re: Crow Foot Fabric
Dear Shekhar Dey,
To answer your questions:
You are looking at fabrics 900 to 1400gsm in the strength range that you quote and for an effective rip resistant weave you would need about 180kN/m weft strength.
For steel cord belting I do not think it would be effective , or no more effective than any other fabric with a suitably heavy weft. The reason is that in a ripping event with steel cord belt there is generally an object wedged between the cords so the characteristics of the fabric weave are negated. It is only the weft that is acting. Steel cord manufacturers have carried out their own research on the design of rip resisting fabrics for their belts.
All Crows foot weave is 2x2 broken twill weave and it is the balance of warp and weft that can make it rip resistant.
regards,
Ray L ■
Re: Crow Foot Fabric
Dear Dey,
Mr. Latchford is correct in not recommending the crow-foot weave (CFW) for steel cord rip-resistance.
CFW can be used for steel cord:
a) impact resistance
b) splice reinforcement
c) lowering rolling resistance due to reducing idler roll indention into belt's cover rubber between roller and belt.
Rip or Tear Resistance fabric applied to steel cord uses a strong weft and weak warp. Look at major belt mfg literature with their demonstrations such as: Goodyear, Phoenix AG, Bridgestone, et al.
Lawrence Nordell
Conveyor Dynamics, Inc.
www.conveyor-dynamics.com ■
Re: Crow Foot Fabric
Dear Mr Dey
It is good to see all the experts' opinion already given to your query.
I'd like to add a few more lines.
Crow feet weave is indeed a Broken Twill Weave, one of which is a 2x2 variety (where each warp passes over & under 2 weft threads at a time). Generally this is the most popular type and hence is more associated with CFW in the belting industry. There are some variants to this design too. One of which is a normal broken twill weave, where ,warp will pass over & under 1 weft at a time instead of 2. There is a third variety where 2 warp pass in pairs over & under the weft similar to the above, which is called oxford broken twill, that can be both 2x2 or normal (1x1)broken twill.
There are many other varities of broken twill as well. But they are not associated with the Crow feet Weave terminology.
Regarding the preference of CFW over plain weave is well described by Ray L, where tear resistance is the most important criteria. This weave is popular only in heavier styles, where the warp thread has a bigger diameter and no. of warp is also higher for strength reasons. This makes insertion of weft difficult during weaving specially when more no of heavy denier weft has to be used for higher weft strength also. CFW reduces the coverage factor and increases the ease of weft insertion. This also leads to a reduced warp crimp (compared to a plain weave design) which again influences many belt performance related factors.
Rgarding the tear resistance fabric to be used in steel cord belts there is a special fabric available only for this application called the RIP CHECK BREAKER fabric. This is a heavy denier weft material loosely held by thin warp cords through a leno weave. This gives both high impact reistance as well as good tear resistance properties to steel belts. World leaders of belting industry use this special fabric for the said purpose.
We are the producers of all these fabrics as described above & supplying to customers across the globe. We also make customised fabric as per user's requirement.
In case you need any further clarification , you may contact me over email at : sdas@srf-limited.com
Regards,
S Das ■
Crow Foot Fabric
will you please highlight about this fabric design about the usage
in belting in compare to plain weave or double weave mentioning
the technical advantage if any . ■