Issues casting prints


#1

HI,
First of all I want to state that I love this forum, great feedback and active community!

Now my problem:
I own form2 and print in the castable resin V01.
I send it to two different casting houses

  1. Big casting house who also print themselves on EnvisionTec (uses Vacum casting)
  2. Small local caster who uses centrifugal casting and does not own any printer

Results with different casters:

  1. (Big company) Good to almost great casting results
  2. (Local company) Modest to very poor results (see images): we’ve been having a lot of extremely rough surface and porosity in the gold. Although he does claim to follow the recommended burnout schedule.

    We’ve tried putting the flask in the oven at a higher starting temperature (didn’t fix the issue)
    We’ve coated the print models with HairSpray (which seemed to work once, but the second time it didn’t).

Questions:
What would be the reason for this problem with my local casting agent? I like the guy and we’re undergoing this learning curve together =)
The local casting house uses SRS Silk (Could this be the problem? ) http://www.srs-ltd.co.uk/products_services/silk.html
The Big casting house won’t disclose any of their processes. Although since they have printer themselves I think they might some other process?
I’ve printed several models (1 stone, 3 stones, 5 stones, 7 stones and 9 stones) and cured each in my curing nail salon box for respectively 1 hour, 3 hours, 5 hours etc…
We’re now testing if this influences the casting proces. I’ll keep you updated.

Regards,


Test of Blue-Cast: compatible and castable resin
#2

Firstly i’m a dental tech not a jeweller but we cast various precious alloys in a very similar way.
What you have there looks like either gaseous porosity caused from insufficient permeability of your burnout investment or poor spue-ing/feeding technique.
Maybe ask your local mate to increase the thickness of the sprues, or place a ball reservoir within 1-2mm of the casting and maybe go with 2-3 sprues. Also ensure the ring is away from the heat zone of the mold and the sprues/reservoirs are in the heat zone.
Good luck.
p.s. stick to the manufacturers instructions (time, temp, etc.) on the investment, always.


#3

SRS also have some guidance on casting issues [LINK} Take a look, show it to the casting company.

I use their Classic powder & vacuum cast. I cast with the flask at 500°C (I was casting at 630° but dropped the temp due to some porosity issues) And the metal is at 1020°C, I’ve cast silver & gold at these temps.


#4

Hi,
as general indication, casting service they use long burnout times with steam dewaxing before, cylinders are bigger and they leave investment many hours hardening/drying before starting cycle.

You can expect pretty good results using Plasticast investment and castable V1 with overnight postcuring into uv oven and leaving cylinder at least 2-4 hours before starting cycle.

Other choice you have is to give a try to our resin, no postcuring required, no special investment, and working with 1 hour burnout (fast burnout), just search “BlueCast” on this forum.


#5

Hi All,

So Small update.
The strange thing is that when the local casting house casts my prints he will (almost) always do this together with normal injection wax models.
Therefore creating a ‘combined’ casting tree.
The image below show you a small combined tree casted in silver. With 2 print models (the earrings) and one wax model the ring.

I’m very much thinking the investment is the issue.
Especially because SRS Silk is not really optimize for the synthetic wax models from 3d printers?

Looking forward to your insights.
Regards,

Niels


#6

Look where spure connects to earing, is much better than opposite side.

My opinion is not that the problem is investment but problems are ash residual, investment is not cracked nor damaged.

Solution can be to go with sprue up to opposite part in order to allow more oxygen flow into cavity.


#7

Just printed my first prints using the blue cast resin. Prints look great! Now to see if I can cast them. I have had no luck casting the formlabs castable. Burnout has been incomplete… Will post results of the bluecast castings


#8

What are the size of these objects?


#9

The disks are 25mmm in diameter. Casting 1 disk today using the quick burnout.


#10

Looking forward to your results! =)


#11

What does the surface quality and detail look like? Is it smooth?


#12

Surface finish is very nice! I would say the prints are very similiar to the formlabs castable v2. I tried to cast and had better results but still incomplete burnout. I am trying again on wednesday with a different type of sprue. To be honest I had issues with these disks with milling wax also. Will post results as sson as I get good casting. Will not give up until it comes out perfect.


#13

Hi guys,
I share my experience with BlueCast compatible resin. I have done a test with massive rings. Standard Investment and bornout following the BlueCast guidelines. Good results!!!
The image below show you raw castings


#14

Here is my casting today. Used satin cast, with the 1 hour burnout cycle. Better but still having investment breakdown. Will try again tomorrow with plasticast investment/.

Thoughts ?


#15

With Satin Cast you need set the max temp of fast bornout to 750° C and extend time of 1 hour. Thank for sharing your experience.


#16

Hi Artur,
High and low relief are probably the most difficult casting also with wax because if you think at investment in negative it is made by a lot of small and delicate details in positive.

Anyway some tip to solve issues:

  • use harder investment (plasticast is not harder, is more elastic)
  • alter water/powder ratio lowering water ( 38/100 36/100 …)
  • add boric acid to investment
  • before pouring investment slurry, brush model details with stronger investment (30/100 or also less) and pour on side, not directly on model

We had successfull castings with fast burnout with Satincast increasing investment hardening period to 3/4 hours before fast burnout.

Sprues and position they look ok.


#17

Wow Great result!
No post curing?
How long in alcohol bath?
Nice!


#18

Hi Niels.
my steps:
washing, alcohol shower, and drying (comp.air) 2 times. 3 minutes max for all!
no uv post curing. much easier than expected :slight_smile:
image of raw casting 10x …absolutely perfect surfaces


#19

@arthurr43, are the little “hunks” missing actually investment breakdown? I’m having problems with porosity, but after talking with Rio Grande have narrowed it down to shrinkage porosity or gas porosity. My little missing hunks are in a “star” configuration, which they say indicate shrinkage porosity (I’m no pro at spruing!). Still figuring this out. I’m using Satincast in general, but just ran my first castings with Plasticast.

I do know that my rough surfaces on casting seem to be caused by incomplete curing. I am literally leaving my pieces in the curing chamber for 1-2 days now, and have had no problems. No curing, really, @BlueCat? Ahhhhhh…that sounds nice. What’s approximate shipping to the US?

The technician at Rio Grande, who seemed very knowledgable, said that I need to increase the temperature in my Electro-Melt to 1825°F (996°C) and cast with the flask between 950-1000°F (510°-538°C) in a vacuum casting setup (non-inert gas shielded type).

@RickyMcG, nice castings…


#20

@arthurr43, are the little “hunks” missing actually investment breakdown? I’m having problems with porosity, but after talking with Rio Grande have narrowed it down to shrinkage porosity or gas porosity. My little missing hunks are in a “star” configuration, which they say indicate shrinkage porosity (I’m no pro at spruing!). Still figuring this out. I’m using Satincast in general, but just ran my first castings with Plasticast.


Have not tried the bluecast with plasticast yet… That test will come next week. Cast again with satincast today. Longer burnout but still have some investment breakdown. Will keep trying.


I do know that my rough surfaces on casting seem to be caused by incomplete curing. I am literally leaving my pieces in the curing chamber for 1-2 days now, and have had no problems. No curing, really, @BlueCat? Ahhhhhh…that sounds nice. What’s approximate shipping to the US?

The technician at Rio Grande, who seemed very knowledgable, said that I need to increase the temperature in my Electro-Melt to 1825°F (996°C) and cast with the flask between 950-1000°F (510°-538°C) in a vacuum casting setup (non-inert gas shielded type).

I bring the flask up to 1825 F and cast at 900F Have never had issues on wax, still working on learning curve :slight_smile: