FAQ

In general, you should consider grinding the surface of the Rubber Belt if any or all of the following conditions exist:

1. Rubber Belt hardness varies more or less than 10% (15% maximum) of its original reading. (NOTE: If forgotten or unknown, this original reading can be approximated by checking the hardness of the Belt on its edge, as this area does not come into direct contact with the heated steam cylinder and finishing chemicals.)
2. The surface of the Belt becomes shiny or glazed. In this condition, the belt loses its grip on the cloth and thus, its ability to effectively carry water.
3. Penetration of chemicals and finishes in the surface of the rubber that reduce the natural ability of the Belt to shrink fabric.
4. Surface cracks or other blemishes on the face of the Belt. These will worsen if not removed. We strongly recommend immediate action.

REMEMBER: IT IS BETTER TO GRIND MORE OFTEN THAN NOT ENOUGH. If properly ground, and ground at the optimum time, a more frequently ground Belt will not only outperform an infrequently ground one, but will also last longer.

 How to Grind see: Technical Support -> Grinding

All rubber belts should be washed after every grinding and whenever build-up of “sizing” accumulates on the belt’s surface.

• Belts need to be washed after grinding to remove “surface tension” and allow cooling water to adhere to the belt’s surface. This is important to prevent surface cracks.

Chemicals and finishes from the fabric can accumulate on the surface of the belt reducing the rubber’s ability to shrink fabrics. A number of factors influence this build up, and experience is the best guide to determine how frequently the belts must be washed to remove it. Please contact Dunline for advice specific to your fabric processing needs at beltinfo@dunline.com

Fine tuning the correct amount of tension on a Rubber Belt is largely a function of experience. Several variables, including the current thickness of the belt, the style of fabric being processed, etc., need to be taken into account for an accurate determination.

In general, however, the proper tension on a 67 mm (2 5/8″) thick Rubber Belt can be approximated as follows:

• With the rubber blanket tension set at the minimum position, draw two (2) lines*, 30.5 cm (12″) apart, on the edges of the blanket. Make these lines on BOTH belt edges, that is, on both sides of the belt.*NOTE: On a new DUNLINE® Belt this has been done for you, although, with wear, the marks may need to be reapplied.
• Increase the tension evenly, until both lines are 31 cm (12 1/8″)apart to a maximum of 31.3 cm (12 1/4″).
• Turn the belt (4 – 5) complete revolutions. Stop the machine with the line markings between the tension and guide-rolls. Confirm that the amount of stretch is still 31 cm (12 1/8″) preferably, to a maximum of 31.3 cm (12 1/4″).
• Start processing fabric.

*NOTE: Thinner Rubber Belts, 51 mm (2″) or less, may need up to 8 mm (5/16″) additional stretch per each 30.5 cm (12″).

TO FINE-TUNE BLANKET TENSION:

If the fabric shows any corrugation, it may be necessary to increase the tension or stretch slightly.

Have a worker on each side of the tension roll tighten or raise the tension roll one turn at a time, while watching the fabric. As soon as the corrugation disappears, increase the tension by one more turn.

REMEMBER:

IT IS VERY IMPORTANT THAT THE RUBBER BELT IS RUN WITH THE LEAST AMOUNT OF TENSION POSSIBLE. EXCESSIVE TENSION REQUIRES AN INCREASE IN COMPRESSION TO ACHIEVE THE DESIRED SHRINKAGE. THIS RESULTS IN DECREASED RUBBER BELT LIFE.

IDENTIFYING  OVER-TENSION:

Too much tension reduces the relative compression that exists on a Belt. In essence, a tighter belt means less recoil and less potential shrinkage. Excessive fabric tension can exist in many different areas throughout the machine set up, but is generally at fault in the following areas:

1. Between the A-Frame or J-Box and the Sky House or Cole Spray (Moisturizer).
2. Between the Moisturizer and the “nip” area of the Rubber Belt.
3. Between the Rubber Belt and Palmer units.
4. Between the exit end of the Palmer and the take up roll on the exiting A-Frame or J-Box.

REMEMBER: A SANFORIZING machine is meant to shrink cloth, not stretch it.

NOTE: The use of a shrinkage indicator (a transducer connected to a shrinkage monitor) at any critical point mentioned above is beneficial in determining whether or not shrinkage is being pulled out at that particular point.

For the proper way to tension your belt please see: “Technical Support Tension”

Be sure to calibrate this setting after the installation of a new Belt and after every grinding session. Without proper calibration, it’s difficult, if not impossible, to know how much compression is actually being applied to the Belt. Obviously, if insufficient compression is being applied, the result may easily be less shrinkage than desired. Conversely, excessive compression will degrade the rubber surface faster, shortening belt life. Please see our instructions on how to properly Calibrate The Compression Plate in  “Technical Support Calibration of Compression Rolls”

The answer to this question obviously depends on the severity and type of problem and, sometimes, what odds one is willing to take. Some patches, for example, are a high risk, but, nonetheless, still performed as the Belt has a lot of useful rubber remaining.

• Surface Cracks: If the cracks are small they may be ground away. Ensure that proper settings and adequate water are cooling the belt to prevent further cracking. If cracks are somewhat larger they may be patched.
• Edge Cracks: Cracks or cuts on the edge of the belt may be addressed through hand grinding, trimming, and/or patching. Please contact us with pictures of the damage so that we may advise on the best solution.
• Interior Cracks: If caught early these may be hand ground away.  Interior crack are difficult to patch but if they get larger this is required to maintain useful life of the belt. If the crack gets larger patching is required, but if the cracks are numerous
• Burns: As the belt is made of natural rubber, it is susceptible to being burned if not properly cared for – particularly if it is left resting against a hot steam cylinder. The only solution for a burn is to grind. Hopefully the burn is not so severe that a grinding cannot rectify the damage.

For directions on how to best treat each form of crack please see Technical Support Patching / Cracks.