Our company have developed a new belt fastener made with a multiply synthetic textile structure, rubber as cover material, metal inserts under the cover and self taping screw. You will installe this flexible fastener by placing the belt between the top and the bottom of the fastener and fixing them with the self taping screws. Different fabric strength and cover (heat resistent up to 180 °C) allow the "Super-Screw fastener" to operate under various condition. Some customers use it also for steel cord belt up to ST 1,700 and pulley distance of several miles.

It's possible to use it also in order to repair small holes, rips and border damage. In opposition to repair kit it will not remove because the metal pieces inside of the fastener held the screw in position.

You will find further information on our web site.

Regards

Edgar Jakob

MLT GmbH

www.mlt-deutschland.com

Attachments

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If I understand the problem described correctly, in my opinion, the belt is not repairable.

I assume the failure is noticable on the top cover first. This could be a tensile fatigue failure and not induced by product impact at the load station. I could be from buildup on the pulley surface, however, my guess is it is rubber property related.

Transverse cracking indicates the rubber has been preferentially strained beyond its elatic limit along the crack axis. The elastic limit has [robably been lowered by the heating process. Bending over the pulley arrangements with their strain induced diameters, proximities and quanties, is the likely source of the rubber fatigue fractures.

If this hypothesis is true, then much of the belt is damaged to a greater or lesser degree than is obserable with the crack locations. Applying the same failure process will only generate added failures.

Write a belt specification that will meet the intended service. Revisit the pulley arrangements and their contribution to the failure.

Wish you luck,

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■

Hello Irfan,

Large number of cracks in belt top cover implies that the product (material) has affected the rubber properties, so that it has become less elastic (reduced ability to extend / contract within yield limit). This could be due to chemical reaction and temperature effect by material. This means that the cover material is not compatible to application actual conditions. You may take care of this aspect while replacing the belt.

Pulley diameters and transition length are primarily concerned with carcass, but in your case you can also be liberal for the same.

I do not know your belt width, troughing angle, conveyor length and belt speed i.e. frequency of reversal of stresses in the belt, attributed to pulleys, transition etc. Too deep troughing of belt for short length conveyor is also not good.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Irfran,,

Although I agree with the responses of Mr.Nordell and Mr. Mulani, you may want to try one of thew Eli-flex products as a stop-gap measure.

The Rema products should work if they are compatible with your product, are properly applied (frequently not done), and are allowed to set-up properly (even more frequently not done).

You experience with rapid Rema patch failure suggests that your actual product temperature is closer to 100C than 85C. If this is the case, review your process parameters before replacing the belt.

Regards, ■

Ifran,

It appears here you may have a long term issue here that will require replacement of the belt, there are some solutions for your immediate problem.

A good belting company would have no difficulties in carrying out a hot repair to these holes.

This involves cutting out an area around the hole (carry & return covers) and vulcanising a new piece of rubber in. This is a very good repair method and when finished the repair is level with the surface of the belt so your cleaners dont need to be backed off.

To do a repair 300mm x 300mm would take around 4hrs depending on the vulcaniser the crew uses. A Shaw Almex superspotter is ideal for this and a lot quicker that having to use transverse bars etc.

You could also prepare the repair in the same method but fill with a cold repair material such as Rema-Tip Top CN filler or Nilos TS filler. This doesnt rely on vulcanising , merely the bonding of the cold cement. This also doesnt require the cleaners to be backed off. This method is slightly quicker than the hot repair method. The belt would need to be relatively cool before attempting this or it will affect the bond. This may have been a issue with the patches you use.

My experience with Epoxys and two pack fillers is that often they are a lot harder duro then the belt. This cause's problems when going around pulleys,especially when repaired across the belt.The flexing often cause's these repairs to fall out.

Let me know what you end up doing with this belt

Shane ■

Hello again Irfan,

I agree that hot repairs are better than cold cure repairs. However, I disagree that cold cure repairs are faster -- this ignors the set time required for the cold cure repair material.

If you have full width cracks with ocaaional holes, repair both the holes and the cracks via the hot repair method. Also, putting in breaker fabric will help. Using a full width press, such as the Shaw Almex vulcanizers, will cure the repair material in approximately 45 minutes after the repair has been made. This compares with the 12-24 hour set period after making the repair required by cold cure methods.

Considering the extent of the problem, as expressed in your post, you should consider a replacement belt.

Regards, ■

Dave,

I am unsure of what cold repair method you are refering to that requires 12-24 hours curing time.

I am only familiar with cold repairs using such products as Rema,Conti & Nilos. These repairs require curing time of 30-45mins per coat of glue.Obviously cure time then varies with the number of plies repaired, but it takes nothing like 12hours.

Can you please explain to me what method you are refering to

Regards

Shane ■

Hi Shane

Below is taken from the Rema SC2000 Spec sheet.

As you can see, Rubber to Rubber strength increases nearly 50 % over a 12 hr period and is increased 2.5 times over 7 day period.

Unfortunately, in our game we do not have the luxury of having the systems down for that amount of time so we evaluate the situation, and if possible short cut the manufacturer’s recommendations. [ Time is money ]

Ambient Temperature has a lot with the curing of most adhesives so the table below will vary accordingly.

I think you will also find most epoxy’s have full cure time in the 24 hr plus range.

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Hi Shane,

The 30 to 45 minute time frame that you are referring to is the practical (i.e. typical field use) time used by applicators to apply the set-up coats of Neoprene (polychloroprene) two-part cements, not cure time. As Bruce Baker has pointed out, the manufacturer literature actually calls for more time between coats.

Regardless of this time, the "cure time" referred to in the manufacturer's literature is the time after the coats have been applied and the patch rubber stitched in place. ContiTech, Nilos, and Rema literature all recommend a 24 hour set-time (with temperature around 25C) at this point before placing the repair in service. If you talk to their sales staff, they will "unofficially" state that it is safe to put the belt, pulley lagging, etc. in service after 12 hours - but they will not put this in wriing.

Therefore, the cure time as defined by the cement supplier is 24 hours at 25C and 50% max RH. Compare this down time to the 1 hour requirement for hot vulcanization. If the system is time sensitive (i.e. if down time is an important cost factor), the hot method is far less expensive than the cold.

When using cold cure cements, you can reduce the set-time (cure time) if the ambient temperature is higher than 25C -- but you have to add time if the temperature is below 25C and if the relative humidity is above 50%. This is one of the reasons why some cement manufacturers (Pang, Rema, etc) offer presses to use with their cements - the added heat & pressure reduce the cure time and provide a better repair/splice.

Regards, ■

any one has used conveyor belts.if does pls contact us .any sepcs should be good for us

DaZhao Wang

Phone: 86-571-86983555

Fax: 86-571-86725215

e-mail:Thmec@conveyorbelt.com.cn

website: www.conveyorbelt.com.cn ■