Preventing Premature Rubber Belt Failure

Dunline > Technical Support > Preventing Premature Rubber Belt Failure

Premature Belt Failure is largely due to maintenance issues, the most common of which are as follows:

  1. Too little water

    Without water to cool and lubricate the belt the surface will become tacky or sticky. When this happens the belt will “chafe” and stick to the steam cylinder, particularly on the edges outside the cloth line. As the Belt chafes and the durometer drops and the rubber becomes susceptible to actually “peeling off” or “picking away” from the Belt – adhering instead to the hot cylinder. At this point, it is imperative to grind immediately to eliminate irreparable damage. If left unattended, for even short time periods of 30 minutes, the chafing can develop into minute surface cracks. In time, these cracks will grow until controlled by grinding, patching, etc., or until they render the Belt useless. Please see water spray position diagram.

  2. Stop or Guide Rolls

    Cracks may develop on the edge of a Rubber Belt if the Belt is allowed to run forcefully against either or both of these Guide Rolls. Please see Positiioning Stop/ Guide Roll

  3. Excessive Compression of the Rubber Belt

    The maximum recommended compression of a Rubber Belt is 25% of its current thickness. This is generally sufficient even for heavy weight fabrics like denim that require 14-16% shrinkage. Compression in excess of this recommended amount results in additional stress on the Rubber Belt and may result in premature failure, including cracking. To ensure you are not inadvertently over-compressing the belt make sure you calibrate the shrinkage plate as advised here.

  4. Too Much Heat or Too Little Heat

    Depending on the fabric being processed, the recommended temperature range for the Steam Cylinder is generally 240 – 290° F (115 – 143° C). Exceeding the high end of the temperature range will result in faster degradation of the natural rubber that, in turn, will necessitate more frequent grinding. Conversely, running the steam cylinder with a temperature too low will cause chafing to occur because the belt isn’t properly slipping against the cylinder. Instead it “chatters” against the cylinder. This constant chattering against the cylinder will lead to cracking.

  5. Too much Tension or Stretch

    General Rule: Operate the Rubber Belt with as little tension or stretch as possible. (Excessive tension requires an increase of compression on the Rubber Belt in order to achieve the same amount of shrinkage).
    Follow these General Guidelines:

    • 2 5/8″ (67mm) DUNLINE Belt – when new, preferably stretch 1/8″ (3.17mm) to a maximum of 1/4″ (6.35mm).
      Note: The 12″ (305mm) mark located on the side of the Belt* should now preferably read 12 1/8″ (308mm) to a maximum of 12 1/4″ (311mm). If fabric corrugation exists at this point, increase this stretch very slightly until it disappears. Continual adjustments will be required as the Belt is ground and becomes thinner. See 2″ (51mm) rule below.
    • 2″ (51mm) DUNLINE Belt – stretch preferably 1/4″ (6.35mm) to a maximum of 1/2″ (12.7mm).

      Note:       The 12″ (305mm) mark located on the side of the Belt* should now preferably read 12 1/4″ (311mm) to 12 1/2″ (318mm) maximum. If fabric corrugation exists at this point, increase this stretch very slightly until it disappears. Continual adjustments will be required as the Belt is ground and becomes thinner.

      *Note:       DUNLINE places these marks on all new belts shipped. With age, however, these marks will fade and will need to be reapplied. Obviously, the marks should be placed as accurately as possible to help insure the proper tensioning of the Belt.

  6. Improper Grinding

    Improper Grinding of the Rubber Belt – failure to properly restore the Rubber Belts surface commonly results in the premature formation of cracks.

    • Generally, cracks develop on the face of the Rubber Belt outside the cloth line. This area is directly exposed to the heated Steam Cylinder and, therefore, is more susceptible to the effects of abrasion, heat, and compression. It is critical to closely monitor this area of the Rubber Belt. Once cracks develop on the surface, it is imperative that they are ground away fully before they are allowed to worsen. Failure to due this may result in permanent damage to the Belt.
    • See Technical support grinding for advice on how and when to grind a Rubber Belt.
    • Remember: PROPER AND FREQUENT GRINDING, WHEN NEEDED, ALWAYS RESULTS IN EXTENDED RUBBER BELT LIFE. Common Fallacy: The less one grinds, the longer the belt will last. This statement is a fallacy as a layer of “dead rubber” will only mean more compression is needed to achieve the desired shrinkage. More compression simply works both the Belt and the machine harder. Ultimately, this means more machine wear, as well as, shortened belt life.