1) How the continuity of cords are ensured while making steel cord belts. If at all , by any reason, if one cord is damaged and needs to be continued with another length of cord, how the manufacturers connect the cords?

Making a new splice normally implies, by common practice, broken cords are removed. In the event they are not, you should seek an expert in steel cord splice analysis to determine if the resulting splice endurance rating is sufficient.

2) For steel cord belt, the factor of safety is 7:1 or 10:1 ?

Both values above are more than ample assuming you are refering to the steady-state value. You can achieve lower numbers depending on the conveyor design.

3) In normal aging, the fabric belts are changed, when the top ply is starting visible. What is the criteria in steel cord belts, to decide the changing?

I assume you mean rubber worn down to cable surface. A rule-of-thumb is there should be more than 2 mm of top and bottom cover rubber left to produce a competent splice. If the belt is worn to the cables, many other factors must be considered including: 1. damage to cable, 2. loss of zinc coating degrading connection between steel and rubber, 3. access to a proper efficient primer coating that bridges the connection between splice rubber and steel cord, 4. required endurance level necessary to achieve a safe operation for anticipate end of belt life - highly worn belts usually have limited life and limited ability to built a proper splice.

4) In wire rope slings, ther are rules to measure the cord dia or the number of wires damaged in a pitch length of the wire rope.

Is there any such criteria or thumb rules guide in steel cord belts?

There are methods to analyze the residual strength of the splice given some cords have been damaged. Not possible to given such detail in the forum. Conveyor Dynamics, Inc. (CDI) apply our Finite Element Analysis (FEA) that has been tailored to steel cord irregularities that shows the peak rubber and steel cord stresses and what they mean to safe operation. ■

You have not made clear if the damaged cords are from breakage, corrosion, or other. This will make a difference on any recommendation. Most curious is why would you make a splice with damaged cords? Normal practice is to remove belt section with damaged cords that fall in the splice zone.

Any recommendation should include:

1. Belt ST-Rating N/mm & steel cord size

2. Age of Belt

3. Splice Pattern - splice steps, step length

4. Location of damaged cables and number that are cut

5. Belt Safety Factor - 10:1 is not as serious as 5:1

When a cable is removed from the splice you should be cognizant of the consequences - beyond the splice the broken cord will carry its proportion of the belt tension. As the broken cord approaches the splice, it will load the adjacent cables on either side of the broken cord. So, both adjacent cables and adjacent rubber between cords will carry proportionately more load than normal. Usually, 1-3 cables are not a problem. 5 or more may become a problem depending on where ( edge vs. center ), edge being worse. The Belt Safety Factor must be evaluated in any prudent solution.

A clear answer is not possible with so little data. ■