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Dunline Rubber Products - Purchasing An Overview
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Suggested care to be taken when ordering, storing and using rubber shrinking belts to ensure maximum useful rubber belt life.

 

There are often considerable differences in the amount of useful life which is obtained from apparently identical rubber belts, used to process identical fabrics, on identical shrinking machines, even at the same mill. In some cases, the difference in rubber belt longevity may be as much as double or even triple.

Obviously an important factor here is accidents which may occur to a rubber belt. Another cause for such disparity is operation technique or skill. It is interesting to note that most rubber shrinking belts are not taken out of service because they have run their normal useful life. Some mills have a policy of removing belts from service arbitrarily, when they reach a certain thickness. We have seen numerous instances where perfectly good rubber belts are removed from service because they have been reduced to a certain arbitrary thickness, when a simple increase in rubber belt length tension would have resulted in such belts being able to perfectly pre-shrink another 2 or 3 million yards of fabric.

The following is, in our opinion, very worthwhile information based on over 70 years of manufacturing and end-use experience with rubber belts.


Purchasing - Source Click to open print-friendly version of this page

The source is an important consideration when determining where to obtain a rubber belt.  The manufacturer, or manufacturers representative is always the best source.  Re-sellers are to be avoided because they often obtain rubber belts from a variety of sources of variable and unknown quality.  They have little or no actual technical knowledge and their reliability may be doubtful.  DUNLINE sells rubber belts only through their authorized representatives and the representatives reputation is fully backed by the Dunline worldwide reputation, assured by a 70 year history.

A considerable number of rubber belts are accidentally damaged during shipping, storage, unpacking or installation on the compressive shrinking machine. DUNLINE rubber belts are always shipped in a substantial high cube, sea worthy packing case. Rubber belts may be stored in this packing case for up to two years. If belts are to be stored for long periods of time, it may be advisable to remove them from the packing case and suspend them on a 36 inch (900mm) diameter roll or cylinder, protected with heavy fabric. This will permit occasional turning of the belt to prevent any belt distortion or “memory- sets” which may require special attention when the belt is finally installed on the shrinking machine. Rubber belts must always be stored in an area away from temperature extremes, ozone gas, petroleum vapors or direct sunlight.

 


 

 
Purchasing - Ensuring Proper Width Click to open print-friendly version of this page
  Width    
1. Maximum width fabric to be processed   __________
2. Min 6 in. (150 mm) or Max 8 in. (200 mm) Edge Face Allowance + __________
3. Ideal Belt Working Face (ordering) Width = __________
4. Edge Type Allowance "C" = 2 in. (50 mm), "R" = 1 in. (25 mm), "S" = 0.5 in. (12.5 mm) + __________
5. Rubber belt overall width = __________
6. Cylinder Face to Overall Belt Width min. Allowance + __________
7. Min. Cylinder Face Width to Accommodate Belt Overall Width = __________
       

The ideal rubber belt working face (ordering) w idth to accommodate maximum cloth width intended to be processed is line #3. To accommodate this width, the rubber belt should be able to process cloth width as indicated on line #1 the cylinder face of the rubber belt unit and the narrowest rubber belt carrying rolls must be at least as wide as the width shown on line #7.

NOTE: To accommodate maximum possible fabric width for any shrinking machine, the "S" type rubber belt edge is recommended.

To determine the widest fabric width capability for any given machine cylinder width, start with figure on line #7. Subtract figure on line #6, 1 inch (25mm). This is the maximum overall belt width allowable (line #5). Now subtract the allowance for the belt edge type (line #4). This will bring you to the ideal rubber belt ordering width (line #3). Next subtract line #2 to get maximum fabric width (line #1) recommended for the machine cylinder face width.

Rubber belt thickness: For the majority of fabrics, the 2 58 inch (67mm) thick rubber belt is most commonly used.  In cases where most goods are processed for hand, or are lightweight, low potential warp shrinkage, a 2 inch (51mm) rubber belt may be used and may actually last longer than the thicker belt.  Belts thicker than 2 5/8 inches (67mm) thick are not recommended, as the additional thickness cost is not justified by greater belt useful life.

Rubber Belt Edge Type: Experience indicates that the "S" type belt edge is actually the most resistant to belt edge cracking while offering the widest fabric width potential for narrow shrinking machines. This is because the “S” type edge provides almost the entire thickness of the belt edge to work against the lateral belt limit rollers, thereby reducing the working force of the belt edge, against the limit rollers.

Rubber Belt Hardness: DUNLOP has produced endless rubber shrinking belts for over 70 years. That is longer by far, than any other rubber belt manufacturer. This long experience as the largest manufacturer of these belts, along with the vast rubber belt manufacturing experience of of the DUNLOP worldwide organization confirms that the ideal hardness for rubber shrinking belts used to process virtually all types of fabrics is 38 to 39 degrees Shore "A". This hardness insures both maximum preshrinking potential, as well as ideal fabric hand modification capability.

Rubber Belt Material: Natural rubber has been proven over the past 60 years to posses the best dynamics and physical properties for the specific job of preshrinking and hand modification of textile fabrics. The natural rubber is enhanced by the many other ingredients blended with the natural rubber to improve its physical properties. Some manufactures also blend relatively small amounts of synthetic rubber, usually 15% or less, with the natural rubber. This may be done to improve the wear properties of the natural rubber.

Manufacturing Methods: It is experience which clearly shows us that the "thin ply calendared sheet" rubber belt manufacturing method results in the best performing rubber belts. Other methods such as extrusion, result in streaking of some preshrunk fabrics as a result of lack of uniform rubber physical characteristics across the rubber belt face. Variations in the  extruded rubber belts will extend throughout the rubber belt thickness. This may result in the complete loss of a rubber belt, even when new or almost new.

Service: DUNLINE is the only rubber shrinking belt whose manufacturer has extensive end-use experience. This experience gained over 70 years is without equal. As the world's largest manufacturer of endless rubber shrinking belts, DUNLOP has a broad application experience available from no other manufacturer. When questions arise or problems occur, only DUNLINE has the highly qualified personal to assist customers throughout the 85 countries where DUNLINE rubber belts are used and preferred.

 
Purchasing - Straight Edge Type Click to open print-friendly version of this page

Rubber belt edge type may be a factor of considerable importance. Several years ago when rubber compounds were not as good as those used today, rubber belt edge cracking was a real problem. Partly, as an attempt to cure the problem and partly as a gimmick, the contour edge was introduced. It was hoped that the contour edge would compensate for failure to renew the slight radius on the outer edge of the rubber belts which disappears after two or three routine rubber belt surface grindings. What actually occurred, was that the rubber compounds did improve and belt edge cracking became much less of a problem. Many users attributed the contour edge to the reduced incidence of edge cracking. In reality, the straight edge rubber belt offers much greater resistance to belt edge cracking. The problem today continues to be the failure to renew the outer belt edge radius after routine belt surface grinding. We still see some suppliers offering gimmick edges such as reverse contour etc.

                               Another advantage of the straight edge rubber belt is that it permits maximum machine width utilization. This is quite important as fabrics are being woven ever wider, while shrinking machine width is not always being increased. The straight edge rubber belt offers a rubber belt working face about 1 inch wider than the contour edge belt and at the same time it's greater belt edge area offers increased resistance to belt edge cracking. The important thing to remember is that regardless of belt edge type, the slight radius on the outer belt edge must be renewed immediately, when it is removed by normal belt surface grinding.                          
Figure 4 - Rubber Belt Edge Type Figure 14a - Rubber Belt Edge Type

 

  
Purchasing - Shipping Click to open print-friendly version of this page

To begin with, the best suggestion one can make with regard to obtaining maximum value from rubber shrinking belts is to purchase the very best rubber belt available. We suggest purchasing these belts direct from the manufacturer or the manufacturer's authorized distributors, who clearly identify the manufacturer and the true origin of the product. Often products sold behind the shield of the manufacturers anonymity are offered in this way for reasons of value only to the reseller. Such brands can mean that a reseller purchases from any of several origins on the basis of the lowest price and this often means the lowest quality as well.

DUNLOP, the manufacturer of Dunline rubber belts is the oldest, most experienced, largest and most reputable manufacturer of rubber endless shrinking belts in the entire world. Absolutely no other manufacturer can offer the world-wide reputation and technical expertise of the DUNLOP organization

Ordering a rubber belt is one of the most important factors we will cover. Having already covered "source", we would just mention that it is very important to verify that you receive exactly what you purchased. Some resellers may provide belts which can be as much as 3/16 of an inch (5 mm) under the belt thickness ordered and paid for by the customer. Rubber belt width may also be narrower than paid for. These practices often go unobserved by the customer, but they certainly may affect rubber belt value.

Figure 17 - Shipping Package