The art of belt optimization

How Alphabelt combines different processing techniques to develop the optimum timing belt for every task

To enable a belt to perform its task in the best possible way, it must be equipped with special features. In addition to careful material selection, various modern machining techniques are available to optimize the special functions and properties of a timing belt.

These include:

• Grinding
• Slitting
• (CNC-)Milling
• Punching
• Water jet cutting

These processes can be used for machining both the base belt and the coating and offer numerous design options. By combining several machining techniques and different geometries, very complex solutions can be realized. Machining at Alphabelt is carried out individually according to customer requirements. Here is an overview of the processes and some application examples:

Grinding

Grinding the belt edges

If a belt has to meet increased requirements for width accuracy, grinding processes are used to machine the belt edges. These enable high precision with tolerances of a few tenths of a millimeter. Typical examples of applications are laterally guided conveyor belts, where the profiles of belt and groove must be precisely matched to prevent jamming even in the event of thermal expansion or contamination.

Grinding the back of the belt

Grinding the back of the belt is usually used for two different purposes: First, it can be used to maintain tight dimensional tolerances in the height of the belt. Second, the surface can be roughened by the grinding process in order to achieve a higher coefficient of friction and thus better grip properties, which is necessary for secure positioning, especially with slick or slippery transport goods.

Profile grinding

Profile grinding processes are used to introduce more complex shapes into the belt back, such as rounded or oval contours, slots, bevels and other user-defined geometries according to customer requirements. In the case of conveyor belts, the surface structures produced in this way are mostly used to optimize product guidance.

Slitting

The thicker the coating on the timing belt, the higher the risk of tearing due to excessive bending stresses when enclosing the pulleys. The largest possible deflection radii provide a remedy. Where this is not possible due to the design, tearing can be prevented by slitting. In this case, the coating is cut to a defined depth at certain intervals across its running direction. This reduces the effective belt thickness, decreases the bending stress and increases the belt's bending flexibility.

Milling

Transverse machining of the belt back

With small deflection radii, high bending stresses can occur at the back of the belt, and all the more so the thicker the belt is constructed or coated. Where slitting in the base of the profile would result in excessive notch effects that would tear the coating, the back of the belt can also be relieved by milled grooves across the running direction, if necessary with a suitable radius at the base of the groove. Transversely milled recesses such as prisms or pockets also serve to ensure secure positioning when transporting piece goods.

Lengthwise machining of the belt back

Profiles introduced along the entire length of the belt also enable improved handling of the goods to be transported. Prismatic longitudinal grooves, for example, provide secure and defined holding for strand-shaped products with round cross sections such as cables, pipes, hoses and also sausage. In the case of haul-off belts, the contact area between the belt and the product being conveyed can be increased by means of a precisely adapted back geometry. This distributes the contact forces more evenly over the entire surface and increases friction. Since the contact pressure can be reduced with a higher frictional force, this measure ensures gentler handling and higher dimensional accuracy, especially with pressure-sensitive components. In addition, the conveying speed can often be increased. Depending on the part geometry, the grooves can be U- and V-shaped or rectangular.

Pocket milling

Pockets in any shape and orientation can also be introduced into the back of the belt by milling. A typical application example for this are the vacuum pockets on the back side of vacuum belts.

Removing or machining teeth

Removing individual teeth may be necessary, for example, if they are to be replaced by inserts for mounting interchangeable cams. If keys with screw-in threads are to be used instead of inserts that replace a complete tooth, slotted holes of the appropriate size are made in the respective teeth for this purpose. Machining on the tooth side is performed by CNC-controlled milling to ensure maximum precision and repeatability.

Longitudinal machining of the tooth side

Milled longitudinal grooves on the tooth side are frequently used for vacuum belts. Here, the groove in combination with through-holes forms a suction channel for the applied vacuum. Belts with longitudinal grooves are also used on timing belt pulleys with belt guides. This system is characterized by high tracking accuracy.

Punching

Perforated belts are generally used for vacuum applications in packaging and conveying technology, mainly for transporting light unit loads such as envelopes or as haul-off belts for films. Perforations produced by punching are preferably made in tension cord-free belts or in belts with tension cord-free zones, since cutting through the tension cords with a punching tool would not produce clean cutting edges and sensitive transport goods could later be damaged by wire residues. Depending on the hole size, a suction channel must also be milled in the longitudinal direction on the tooth side.

Water jet cutting

By using waterjet cutting, even complex contours can be produced with high precision. There are virtually no burrs on the cut edges, so further post-treatment is usually not required. Another advantage is that even belts with steel or aramid tension cords can be cut cleanly without the fibers fraying at the interfaces, as would be the case with punching.

There are almost no limits to the design possibilities of the cutouts that can be produced by means of water jets. Triangular and square geometries can be produced just as easily as rounded or oval shapes. For example, the two open belt ends of a belt made from meter goods can be cut out precisely for a welded or mechanical belt connection, regardless of whether the connection is meander-shaped or zigzag-shaped. The through holes in vacuum belts can also be cut by water jet if punching is not an option for the reasons mentioned above. Another application concerns the through holes required for interchangeable cam systems: Here, the holes for the threaded sleeves of the inserts must also be made in the belt with very high precision, so that it is subsequently possible to mount the inserts and the cams precisely. And last but not least, the contours for the cams can also be cut out of PU sheets.

Combined machining techniques

When manufacturing a customized special belt, we often combine several of the above-mentioned processes to achieve an optimum result. We also take into account the dimensions and material properties of the belt and, if applicable, the coating.

We will be happy to advise you on which machining techniques are best suited to your application. Just fill out our contact form!