Natural Rubber Metal bonding issues
Natural Rubber Metal bonding issues
(OP)
Hello dear friends!
The company I work for is facing some problems with the bonding between rubber and metal.
Please forgive the upcoming long post!
The issue appears only on some of the products, mainly the spherical bearings, mostly in the middle area of the product.
The products are vulcanized by transfer process and the rubber is natural rubber.
We've tried many approaches, mainly:
- we've heated the metal parts;
- we've changed the adhesives;
- we've tried that the adhesive reaction and rubber vulcanization to take place in same time;
- we've increased the work temperature;
- and others...(we're facing this issue for a long time now).
Our latest observation, in the lab, is that when we try to bond the rubber already vulcanized on the metal parts the bonding is very, very good. But if we apply small movement the bonding is weak.
We think that maybe because in the middle of the part the temperature isn't as high as it is in the extremes of the part the rubber doesn't get vulcanized uniformly in the entire mass in the same time and although it gets vulcanized the bonding there is weak.
What do you think? Has anyone encountered this problem? Are there any solutions? Are there any good practices to follow?
Regarding the thermal expansion of the rubber, what is the influence of the rubber's condition on it?(vulcanized vs unvulcanized)
Thank you all!
The company I work for is facing some problems with the bonding between rubber and metal.
Please forgive the upcoming long post!
The issue appears only on some of the products, mainly the spherical bearings, mostly in the middle area of the product.
The products are vulcanized by transfer process and the rubber is natural rubber.
We've tried many approaches, mainly:
- we've heated the metal parts;
- we've changed the adhesives;
- we've tried that the adhesive reaction and rubber vulcanization to take place in same time;
- we've increased the work temperature;
- and others...(we're facing this issue for a long time now).
Our latest observation, in the lab, is that when we try to bond the rubber already vulcanized on the metal parts the bonding is very, very good. But if we apply small movement the bonding is weak.
We think that maybe because in the middle of the part the temperature isn't as high as it is in the extremes of the part the rubber doesn't get vulcanized uniformly in the entire mass in the same time and although it gets vulcanized the bonding there is weak.
What do you think? Has anyone encountered this problem? Are there any solutions? Are there any good practices to follow?
Regarding the thermal expansion of the rubber, what is the influence of the rubber's condition on it?(vulcanized vs unvulcanized)
Thank you all!





RE: Natural Rubber Metal bonding issues
Dow has published a technical guide on-line at: http://msdssearch.dow.com/PublishedLiteratureDOWCO... This could have pertinent information in it.
RE: Natural Rubber Metal bonding issues
Thank you for your suggestion but we contacted the supplier, we even changed the supplier, we tested many bonding agents as suggested by different suppliers an still no resolution.
For other geometries there are no problems.
RE: Natural Rubber Metal bonding issues
RE: Natural Rubber Metal bonding issues
Any other ideas or experiences?
Thank you all!
RE: Natural Rubber Metal bonding issues
Is the metal properly cleaned before applying bonding agent?
RE: Natural Rubber Metal bonding issues
- clean the metal surface with sandblasting if it`s steel, or burn it if it`s brass. Allow the metal to cool down before applying adhesive.
- the vulcanisation can be at lower temperatures with extended time depending of the size of the product.
Please inform if this is helpful.
RE: Natural Rubber Metal bonding issues
RE: Natural Rubber Metal bonding issues
First of all thank you for your interest in helping!
An expert came to us and he told us that the problem seem to be caused by air or gasses.
We're going to investigate this possibility.
Thanks again