The authoritative public forum
  for Metal Finishing since 1989
-----

Teflon coating roto molds

I have a cast aluminum canoe mold used in rotomolding that has some porosity. I have heard that some molds are coated with teflon or similar. Iwonder if this will solve my problem.

Ian Crerar
Clearwater design - Kingston, On, California
 

That would largely depend on how bad the pits are. Also, teflon is like a high heat cured paint. Not many places have an oven that will take an 18' part and the aluminum will suck up so much heat that radient heaters will have a problem getting it to temp. Start calling teflon applicators. One may be able to help you out. Give Sermatech a call. They have a very high temp highly filled aluminum paint and they do aircraft parts so might have a facility big enough. They used to have a South FL facility.

James Watts
- Navarre, Florida

Dear Sir,

We would like to have some more details about your mould to be coated. We request you to reply to us so that we can guide in getting the best coating for your products.

Regards,

Tapan Jayant Thanavala
- Mumbai, Maharashtra, India

---

Dear sir,

If your mold has porisity you can weld it with tig.....on the areas keep the heat going and try it work the porisity out. If its like sand or casting flaw in the aluminum try to work it to the top when your welding and keep adding new rod until to form a hump where the porisity is at. if it's porisity from just holes and pits in the mold then just weld like normal to fill holes and build up to a hump. You will have to make a hump with new metal over the porisity so you can rework it down to the rest of the mold.it is alot easier than trying to sand out a hole and also keep in mind you will have to have same texture as surronding area or features so you have the same part as intended for mold wether it be shot peen,sandblast,class a, class b,120 grit,240 grit,600 grit(which is like a mirror finish) etc. teflon coating makes parts come out easier. It would fill voids in casting mold but it will also shrink part if the mold wasn't intended for that type of texture.

Shane Fisher
- St. Cloud, MN, USA
2006