Rubber Roller Covering Strategies – Strip extrusion vs. Three Roll Building

You’ll find a variety of approaches of applying rubber to a metal core in an effort to manufacture a roller. Get a lot more data about รับหล่อลูกกลิ้งยาง

By far the most typical tactics are:

Wrapping a prepared calendared sheet of rubber around the core, that may be held involving two points in a lathe.

Extruding an endless rubber strip and applying it to a slowly rotating core which is fixed involving two points in a spin station.

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

Putting the core between the rolls of a Three-roll-builder and covering it with an endless calendared sheet of rubber – a roll of which is placed within the Three-roll developing machine.

You’ll find benefits and disadvantages to each and every of these strategies and specific circumstances exactly where one may be preferable to a further.

1. ‘Traditional’ wrapping

The ‘traditional’ wrapping starts with cutting the rubber sheet as outlined by the requires of your roller (width and diameter) and placing the ready core in to the lathe. The core is turned gradually as the rubber sheet wraps about it.

Depending on the diameter needed and the geometry of the calendared sheets this wrapping must be repeated quite a few instances. After reaching the final diameter (plus overbuild) a bandage is often wrapped around the roller inside the same machine for curing purposes.

This method is cheap and valid for rollers of a medium size both in length and diameter. It can be flexible and, offered a roller of 1500 x 500 mm, requires roughly 15 minutes covering time like all set up and handling work.

Inside the case of series production this method doesn’t provide any possibilities of expense reduction. Additionally, it demands calendared rubber sheets, that are far more pricey than rubber batches.

Care will have to be taken as the connecting line among two rubber sheets plus the lack of pressure that sticks the rubber to the core and itself, frequently causes air bubbles. On account of the comparatively low investment expected, this wrapping method is used in almost every begin up company.

2. Extrusion method

Compared to standard wrapping, the strip extrusion method delivers many positive aspects. Firstly there is absolutely no ought to make use of the more high priced calendared rubber; batches which can be fed for the extruder are sufficient.

Secondly there is no limitation inside the roller size. This technique can be used for any roller width and diameter and it really is the only productive method to cover large paper mill rollers.

Thirdly there isn’t any set up time for different rollers as long as identical compounds are used; changing width and diameter don’t affect the process at all.

What’s a lot more the compound remaining within the machine or reduce away in the ends from the roller after wrapping may be used once more without having added treatment.

It’s also possible to cut down the wrapping time per roller by 10 to 20%, with staff preparing the following core although the process continues. And finally, the reject rate can be reduce down to about 50%.

You can find, having said that, some disadvantages. Resulting from the truth that the compound applied to the roller tends to flow towards the ends, overbuilds of as much as 16 mm (on the diameter) is expected.

Important investment – up to ten instances larger than for classic wrapping – and highly skilled personnel are also necessary. On typical it requires a worker six to twelve months’ training to turn out to be an expert in extrusion.

Despite the improvement in rejects, you’ll find nonetheless two percent or much more of rejects caused by air bubbles. Undoubtedly there’s a gain in flexibility and expense reduction, but strip extrusion is just not the final solution in rubber roller covering.

3. Cross head extrusion

For series production – starting with a lot of 15 – 20 identical rollers and quantities in excess of one hundred rollers with identical compound – cross head extrusion is really a superb option.

It also uses low-priced rubber batches and can lessen the covering time per roller (1000 mm wide) to about 2 minutes. Even though at least two, ordinarily three, workers help the process, the personnel time per roller may be cut down to 5 – 6 minutes, one third of your time required for the methods pointed out above.

Even though the advantages are obvious, crosshead extrusion will not be a common choice for roller makers. The primary reason would be the wide selection of various rollers manufactured by the typical roller covering company in combination with all the tiny quantity of identical rollers. You’ll find also diameter limitations together with the crosshead extruder.

Additionally these machines cost a lot more than £200.000 GBP and modest or start-up companies can hardly ever afford such an investment. The capabilities required are also far beyond the average expertise of roller covering. Even knowledgeable companies meet new challenges with this strategy from time to time.

Comments are closed