Rubber Roller Covering Approaches - Strip extrusion vs. 3 Roll Building

You can find numerous strategies of applying rubber to a metal core as a way to manufacture a roller. Get more data about ลูกกลิ้งยางอุตสาหกรรมทุกชนิด



One of the most prevalent procedures are:



Wrapping a ready calendared sheet of rubber around the core, that is certainly held amongst two points inside a lathe.



Extruding an endless rubber strip and applying it to a slowly rotating core that's fixed between two points inside a spin station.



Sending the core by means of a cross head extruder, exactly where the rubber is flowing round the core, as a result covering it.



Putting the core involving the rolls of a Three-roll-builder and covering it with an endless calendared sheet of rubber - a roll of that is placed inside the Three-roll building machine.



There are positive aspects and disadvantages to each of these solutions and certain circumstances exactly where one may very well be preferable to one more.



1. ‘Traditional’ wrapping

The ‘traditional’ wrapping starts with cutting the rubber sheet based on the requires of the roller (width and diameter) and placing the ready core into the lathe. The core is turned gradually as the rubber sheet wraps around it.



Based on the diameter required as well as the geometry on the calendared sheets this wrapping must be repeated quite a few occasions. Right after reaching the final diameter (plus overbuild) a bandage is usually wrapped about the roller within the very same machine for curing purposes.



This method is low-cost and valid for rollers of a medium size each in length and diameter. It is flexible and, given a roller of 1500 x 500 mm, requires roughly 15 minutes covering time including all setup and handling work.



In the case of series production this method does not supply any possibilities of cost reduction. Additionally, it calls for calendared rubber sheets, which are more highly-priced than rubber batches.



Care must be taken because the connecting line among two rubber sheets and also the lack of pressure that sticks the rubber for the core and itself, typically causes air bubbles. On account of the relatively low investment required, this wrapping method is used in practically each start off up company.



2. Extrusion method

In comparison with regular wrapping, the strip extrusion method delivers several benefits. Firstly there is absolutely no need to use the additional high-priced calendared rubber; batches which can be fed to the extruder are enough.



Secondly there is no limitation in the roller size. This method can be used for any roller width and diameter and it truly is the only productive method to cover major paper mill rollers.



Thirdly there isn't any setup time for different rollers so long as identical compounds are used; altering width and diameter do not affect the process at all.



What’s far more the compound remaining inside the machine or reduce away at the ends of your roller soon after wrapping is often used once again without the need of further treatment.



It is also doable to lessen the wrapping time per roller by 10 to 20%, with staff preparing the subsequent core whilst the process continues. And lastly, the reject rate is usually reduce down to about 50%.



You will find, even so, some disadvantages. As a consequence of the fact that the compound applied towards the roller tends to flow towards the ends, overbuilds of as much as 16 mm (on the diameter) is expected.



Considerable investment - up to ten occasions larger than for conventional wrapping - and hugely skilled personnel are also needed. On average it takes a worker six to twelve months’ training to turn out to be an expert in extrusion.



Regardless of the improvement in rejects, there are actually still two % or additional of rejects attributable to air bubbles. Undoubtedly there's a get in flexibility and expense reduction, but strip extrusion isn't the final solution in rubber roller covering.



3. Cross head extrusion

For series production - beginning with numerous 15 - 20 identical rollers and quantities in excess of one hundred rollers with identical compound - cross head extrusion is a fantastic option.



Additionally, it uses low-priced rubber batches and may reduce the covering time per roller (1000 mm wide) to about 2 minutes. Even when no less than two, normally 3, workers support the process, the personnel time per roller may be reduce down to 5 - 6 minutes, one third of the time needed for the methods talked about above.



While the advantages are apparent, crosshead extrusion just isn't a well-known decision for roller makers. The key cause may be the wide selection of different rollers manufactured by the average roller covering company in combination using the modest quantity of identical rollers. You'll find also diameter limitations together with the crosshead extruder.



In addition these machines cost additional than £200.000 GBP and tiny or start-up companies can hardly ever afford such an investment. The capabilities necessary are also far beyond the typical understanding of roller covering. Even seasoned companies meet new challenges with this method from time to time.