There are multiple parts to your question for which I offer three:

1. Growth within the press ends. This should be held to no more than 25mm across the width.

2. Axial misalignment offset to no more than one cord pitch or about 20 mm.

3. Axial misalignment angularity or off-parallel should be no more than 0.1 degree or about 10 mm off 5000 mm centerline control either side of the splice.

The last point 3 refers to the holding of the snap-string centerline chalk lines between two opposing ends during vulcanizing.

These tolerances are adversely affected by poor splice construction techniques such as cable stripping, noodle rubber application, cable alignment, etc.

We specify the splice to have a side to side total variation of no more than 50 mm within a 50 m length considering both sides of the splice.

Looking forward to other comments on the same. ■

I failed to note that I was refering to steel cord belt. I do not have much experience with fabric belt vulcanizer controls and installation accuracy.

Hopefully, you will receive comments from knowledgable sources. ■

Hi

I would think 5 mm would be the maximum permissible for misalignment of belt ends after the completion of the splice.

A few tips to ensure the completed splice is straight:

1/ Presuming the belt ends are string lined prior to splice lay up, if so the centre belt marks should line up exactly at both sides of the splice.

2/ Checking the edges of the belt ends with the string line is also good practice if there is any doubt prior to lay-up.

3/ When the technicians are laying the cables and gum, make sure that they are string lined for straightness both sides every 5 to 10 cables.

4/ Have plenty of splice table available each side of the splice, this ensures the centre marks are well spaced.

5/ Suitable Edge bars, length, thickness and width. ■

Do you own a belt slitter? ■

Most quality conveyor belt manufacturers have excellent procedures for setting up a splice so it is aligned correctly. If followed you will not have a problem. Unfortunately most belt splicers do not follow the procedures recommended by manufacturers as they have short cuts such as how the strip the fabric in a fabric splice (and thus distort the fabric axially) or how they prepare the finger rubber in a steel cord splice and find they do not have enough space to fit all cables in. Get a splice handbook from Goodyear, Bridgestone,Yokohama or Continental and read up on their procedures and then make sure your belt splicers follow the rules on splice preparation and execution instead of their own. ■

Bravo, Bravo, Bravisimo.

lzaharis ■

Dear Mofidi,

The allowable splice (or belt) misalignment will vary with the process under consideration. For example very small misalignment is a major problem for belts that are used to make a product or are contained by rigid guides (Gypsum Wallboard Forming Belts, Package Handling Belts, Small Processing Belts are examples of this requirement). Belts used for Bulk Material Handling can Generally tolerate greater misalignment.

The Rule-of-Thumb that I use for bulk material handling belts, that are properly sized and loaded, is that no part of the belt (Splice area included) can run off the system idlers or pulleys, or create a spillage problem (such as leaving a gap at load points).

Obviously with this rule, the amount of free idler and pulley space available will cause the allowable mistraining to change from system to system.

The value of 50mm (2 inches) provided by Larry Nordell for steel cord belts will give a very noticable mistraining, which may or may not be a problem. The value of 5mm provided by Bruce Baker is tight, but achievable if all precautions are taken and the belt ends are straight. Note that Bruce is talking about the splice lay-up and and Larry is referring to the effect of a slightly misaligned splice. Because of this, their two values are actually quite close.

The comment made by Colin Benjamin is well made. Proper procedures, material, tools, time, and space are all important to make a good splice. Taking shortcuts or distorting the carcass will normally lead to severely misaligned splices.

Regards, ■

The misaligment is only what you can tolerate in your system such as Dave Miller's comments.

Another thing that is often overlooked and I have seen it many times. Look for the return belt rubbing on the structure. I have actually seen cases where the belt cut into the structure so bad that the frame had to be rebuilt.

Hope all this helps.

Gary Blenkhorn ■