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Lost Wax Casting of Acrylate Resins - Or How Do I Burnout This Stuff

Paul Finelt
posted this on July 14, 2013 12:55 AM

Here is the low down on getting a good casting out of ANY acrylate... in standard gypsum-bonded investment -  Kerr Satin Cast 20, et al

The following ASSUMES YOU HAVE GOOD AIRFLOW IN YOUR OVEN. GAS-FIRED OVEN PREFERRED.

1. Keep the volume of resin you are burning out to a minimum. (NO SOLID SPHERES)
      a. this applies to the part(s) themselves as well as the TOTAL resin weight.
      b. Use a small flask-  it forces you to keep the resin volume low.
               1. it has the added benefit of better temperature control inside the flask ie your flask temperatures are more likely to match your controller/desired oven temps
     c. DO NOT OVERLOAD YOUR BURNOUT OVEN.
     d. notice the parts that others have had success with and those that have failed.... ( the key factor is the Volume / Area ratio - solid spheres=failures )

2. DO NOT ATTEMPT TO STEAM DE-WAX THIS MATERIAL. It doesn't.
     a. Don't even steam de-wax the sprue/tree. You are risking failure.

3. Wait AT LEAST two hours (preferably 3-4 hours) after investing before you move (yes move) the flasks.
     a. standard practice , but I'm reminding you... touch the flasks after you've set them aside to dry and you are looking for trouble. Someday you'll find it.

4. Burnout Cycle
     a. Dry the Mold & Dewax the sprue/tree - minimum 2 hours at 200degF for most flasks sizes.
     b. Get the Acrylate out before the investment goes through it's weak temp - ramp from 200degF to 550-600degF as quickly as possible. Hold for 1 hour.
     c. Finish the burnout cycle -  Top out at 1200degF for your normal hold time.
     d. drop to your casting temp - hold at least 30 mins before casting

Please:
1. don't burn(overheat) the metal  and/or use 100% scrap or filings and blame the resin for your poor castings.
2. Write down / take pictures  (gather data) on what you've done... so you can learn from failure.
3. Share your results,  as I've just shared my 40 years of casting experience with you.
4. Try platinum investment.
5. Try other investment powders
6. Try investment hardening additives.
7. Share your results.

 

Your "mileage may vary" with your equipment, product, technique and level of expertise and experience.

Shared Sincerely,

Paul Finelt

 

Comments

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Monger Designs

Thanks for educating us, oh almighty casting expert. Lol

July 14, 2013 02:59 PM
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Paul Finelt

Thank You Monger for bringing to light the subject... Important to many it is. 

 

Welcome you are Casting Master Monger - may the force be with you in your quest for casting perfection... 

Share the force you must so to the Dark Side you not succumb.  ;-)

 

LMAO

 

 

July 14, 2013 04:20 PM
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Daniel Bostrom

There is an investment made specifically for plastic/resin models.  It is stronger to resist damage from the expansion of the plastic during burnout.  It's Ransom and Randolph's PlastiCast Investment, available at most fine jewelry supply stores.

August 12, 2013 05:57 PM