By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Non-Ferrous Casting

Moulds with styrene cores and patterns.

All Topics | Latest Posts

Search for:  in Thread Title in  
Guy Lamb23/11/2018 17:50:05
109 forum posts

Can I ask has anyone had experience (good or bad) of producing non-ferrous castings from styrene patterns using green sand? I haven't tried it my self but I was wondering if the styrene patterns could produce gas enough to disrupt a green sand mould.

Guy

Michael Cox 123/11/2018 18:13:26
555 forum posts
27 photos

I regularly make lost foam castings by just burying the foam in loose dry sand with a foam riser protruding above the surface. No need for greensand or venting.

Mike

John Purdy23/11/2018 19:07:10
avatar
431 forum posts
252 photos

Guy

I have made a number of bronze castings using the lost foam method in green sand with no problems. I used the rigid blue close cell foam used for insulation (not the white bead board) and used normal risers and venting. Just stand upwind and don't breath the smoke from the burning styrofoam !

John

Mark Rand23/11/2018 22:13:40
1505 forum posts
56 photos

When our factory (Willans& Robinson/English Electric/GEC/Alstom Victoria Works, Rugby) still had a foundry and made castings for EE and Ruston's Diesel engines up to the early '90s, they were all made from lost polystyrene foam into green sand. That was with SG cast iron.

Guy Lamb24/11/2018 17:59:40
109 forum posts

Thanks Gentlemen, I shall have a try with a polystyrene pattern and report back. Mike's success with dry sand is also food for thought.

Guy

An Other24/11/2018 18:43:10
327 forum posts
1 photos

Guy,

Like Michael, I have also made many lost-foam castings in dry sand, with no problems. I used the smallest grain sand I could find - almost like dust. I also used some quartz sand such as is sold for swimming bath filters. Make sure the pattern is well covered by the sand - if it is too close to the surface, then odd things happen. I assume the that as the foam evaporates in the heat, either the resulting gases 'explode' through the sand, or the sand collapses into the void. If it is buried a few centimetres under the sand, this doesn't happen.

I also use the rigid closed cell foam as mentioned by John Purdy. This stuff can be cut with a fine saw or hot wire, and can be sanded to a smooth finish. The white bead type foam is useless. You can make complex patterns by gluing together pieces of foam using hot-melt glue. No draft is necessary on the pattern.

The principle is described in many places online. This site gives a good description of commercial application: **LINK**, It mentions using a ceramic coating to form a sort of 'skin' to reduce the roughness caused by the granularity of the sand. Since I couldn't get hold of any kind of ceramic dip, I tried a suggestion I found online that coating the pattern with a thin coat of latex paint also gave satisfactory result - it does seem to work.

As John says - don't breath the fumes !

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate