Depending on who you ask, you will get a different answer. Going back many years, all splicing companies worth their salt used edge irons in hot vulcanized splicing. All of the more skilled & reputable splicing companies carry varied sets of edge irons for field splicing in their gang boxes. However, over the years, lax oversight & laziness has led to many splicers using scrap pieces of belt to brace the belt edges that is being vulcanized. All reputable manufacturers of conveyor belting require the use of edge irons when splcing their belting within their splicing manual. The more reputable belting manufacturers have their splicing manual & procedures certified under ISO. The maing resoning for using edge irons are two fold.

1) When a belt is being manufactured, long edge irons are used to provide a solid surface in which the belt will press against under the pressure of the vertical press. This surfcae is necessary to make sure the edges are solid after curing and a condition called "porosity" does not occur. Porosity is a condition in which the edges look spongy after curing. This is a sign that air was escaping from the edges of the belt.

2) When performing a filed splice, it is an attempt to mimic the same process as found in manufacturing. Further, the field splice is a process where on original belt is basically deconstructed & then reconstructed. The edge irons are crucial in creating transverse pressure when the heat & pressure is applied to the splice. Further, when using strips of belt, the strips have to be cut away from the edges of the spliced belt as they are curing with the splice. When cutting the strips away from the splice, the integrity of the splice can be compromised. Edge irons can be seperated with a blade, leaving a clean, sealed surface. This not only helps create a stronger, more solid splice, but it is a better looking splice as well.

I hope this is helpful.

Buddy Wilson

Applications Engineer / TSM-Southeast

Fenner Dunlop Americas ■

As Mr. Heilman said, you need to secure against the press pressure.

Typically, a vulcanizer applies a >100 psi with a field vulcanizer. The ends resist the pressure with a cold zone and silk seal. The sides must withstand the equivalent hydraulic pressure on the edge bar (steel or other).

I would believe the rubber strips could not hold the pressure, besides deforming with temperature, they are not equipped to hold a true straight edge or maintain the original shape of the cable positions during a typical cure.

Try it and tell about it. ■