The joint in abrasive belts

The joint is the most vulnerable part of an abrasive belt during the sanding process. Knowing the types of joints available, their characteristics and which joint is appropriate each sanding application is key to avoiding problems like:

Parallel marks caused by the belt joint.

Belt vibrations.

Accumulations of residue on the joint.

Wrong direction of rotation of the abrasive belt

Belt breakage.

At Abracom, as a specialist manufacturer of abrasive belts, we make all types of joint necessary for each type of industry and its different sanding applications.

To be taken into account

Joints are normally made with a specific angle or pull to help make a smooth and progressive transition during the sanding operation.

In belts with the overlapping type joint we must take into account the direction of rotation of the belt when placing them in the machine. This is indicated by arrows printed on the belt support. These arrows are usually printed by the manufacturer on the paper or fabric backing of the raw material. The direction of rotation of the belt must be opposite to the feed direction of the part.

Belts with the end joint are bidirectional, they do not need to take into account the direction of rotation of the belt.

The belt joint has an expiration date, which is not exact and depends on several factors, most notably temperature and humidity conditions during storage. In general terms, we can speak of a two-year shelf life guarantee for the joint under optimum storage conditions.

The type of support of the sanding belt: paper, flexible cloth, rigid cloth, film, etc. and the hardness of the contact wheel or roller of the machine application are the main parameters that determine the type of joint to be used.

A special technical adhesive is used to join the belt, which requires pressure and temperature for its correct application. This pressure and temperature vary depending on the type of belt support and the grit size of the abrasive.

The minimum curing time for sanding belts to be used without peeling problems is 4 hours for belts with paper supports and 8 hours for fabric belts and other supports.

Overlapped joint

We use this joint for sanding belts with FABRIC or PAPER backings to obtain the best finishes. The joint has the same thickness as the rest of the abrasive belt. It requires taking into account the direction of rotation of the belt.

Recessed Overlapped joint

We manufacture this joint for abrasive belts with FLEXIBLE FABRIC backing. This type of joint is suitable on fine grits for edge sanding, soft surface sanding and where vibration risks may exist. This joint has a recess, grit interruption, by way of compensation on the abrasive side, we make the joint 7mm wide. It requires taking into account the direction of rotation of the belt.

End joint

We manufacture this joint in abrasive belts with FABRIC, FILM and NON-WOVEN FABRIC supports. The end result is a joint with a tolerance very close to zero with respect to the belt thickness. It is bidirectional, it does not require taking into account the direction of rotation of the belt.

Special film tapes for end joints

A film tape with reinforced polyester threads is used for the production of the end joint. We use a tape width of 19mm to give maximum safety guarantees to the joint area. We have five types of belts with different thicknesses depending on the type of support and abrasive belt grain.

Green Tape:
High-strength reinforced polyester film for demanding applications.
Thickness of 215 microns.
Grit range: 24,36,40.

Blue Tape:
High strength polyester film for heavy sanding.
Thickness of 165 microns.
Grit range: 60,80.

White Tape:
Polyester film combining high strength and excellent flexibility.
Thickness of 112 microns.
Grit range: 100,120,150.

Red Ribbon:
Thin polyester film for smooth sanding and increased flexibility.
Thickness of 75 microns.
Grit range: 180, 220, 240, 280, 320, 400, 600.

Gold Ribbon:
Ultra-thin polyester film for a fine and smooth finish.
Thickness of 50 microns.
Grit range: 800, 1000