RTV Molding Fine-tuning using 3D Printing

August 23rd, 2013

By: Joseph Kuwitzky

The science of combining materials and inserting them into designed and fabricated geometric spaces as a method of manufacturing a usable item has probably been around since collective human need. And while we have progressed in both theory and technology, circumstances still occur in which the today’s mold and cast technology requires fine tuning.

My name is Joseph, and I make molds and cast parts in GROWit’s RTV department. Needless to say, the most interesting part of my job is finding ways to make my job faster and easier. In the spirit of what we’ll call “efficiency,” I requested and acquired the utility of a material mix and dispense machine.


This machine is great! It heats, mixes, and dispenses material without any effort on my part. 

My problem? In its current state, this machine doesn’t mix the proper ratio of material A to B of the material I happen to be using so I need to reduce the flow of one of the materials the machine dispenses.

My Solution: There are a few options I have to correct this issue. The typical method, and one I tried but was not having any luck with, involves playing musical chairs with a bag of sprockets, most of which we would have to purchase, test and then potentially purchase a slightly different one again. Then, it hit me. We have modeling software and 3D printers! So I set out to grow a flow-restriction nozzle that can be inserted directly into the dispensing gun.




After a few tests, I found how to make the perfect nozzle!


I am pleased to report that we are now able to use a previously problematic material in this machine with a bit of 3D printed fine tuning, minus the bag of sprockets.

Contact GROWit for a free quote by emailing sales(at)growit3d(dot)com

You dream it. We GROW it.

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POW :: Mystery Art

February 12th, 2013

RTV Molding - Mystery Art - GROWit 3D

Process: LMC (Leftover Material from a Cup)

Material: Plastic

Purpose: To be honest, it doesn’t really have a purpose, but we know it looks cool and that it just had to be shared.

For those who have just stumbled across this article, GROWit is an additive manufacturing (3D printing) service company based in Orange County, California. We do everything from 3D printing prototypes to small-run production jobs. We have our hands in everything from automotive to aerospace to consumer products; we do it all! If you have a 3D file that you would like printed, go ahead and submit it via the GROWit Upload Center for a free quote.

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Additive Manufacturing Improves Process Times & Quality in RTV

October 10th, 2012

Author: Josh Morrison

In all manufacturing environments there are challenges presented and a need for continuous improvement. In our case, the challenge was posed in the RTV department. Certain materials required extended cure cycles to retain dimensional tolerance and mechanical strength. These cure cycles at ambient temperatures would, in some cases, extend to the better part of a week. The result: 4 or 5 days to find out if you have a good part. This was not acceptable, especially in the condition where a new tool was in the iterative, troubleshooting phase.

The answer to these lengthy dimensional instability and fragility times was in the creation of proper thermal cure cycles. One possible solution was to remove the components from their respective tools and thermally cure them in an oven. The problem with this approach was that we were frequently faced with part geometries that were too unstable or too delicate to remove from tooling in these early cure stages. The only remaining and viable way to fix this issue was to cure the parts while they were still in the tooling. This required the oven to be significantly larger than one housing only bare components. The oven size requirement then approached that of the mold chamber.

Our solution to this challenge? Heat the mold chamber.

There are two basic ways to heat a pressure vessel: conductive heat through the shell or an internal heating element. For our use, we determined that the safest (i.e. preventing possible damage to the chamber due to hot spots on the shell) and most accurate method of heating the chamber was via an internal heat source.

An internal heating system was designed and  incorporated as a closed loop control system. This system required several custom designed components, two of which were favorable for production utilizing in house additive manufacturing technologies. Both components were produced in the FDM® process to utilize the low cost and high strength materials this process offers.

Control Box

The first component produced internally was the control box. This box was not constrained by thin walls, nor did it have high heat requirements.

The second part produced for this system was much more stringent on the material requirement. This was the internal heater mount. Because of its location in the pressure vessel, the mount must be able to survive in excess of 200° F. The low cost FDM process offers a polycarbonate material with a service limit of around 280°F .

Internal Heating Mount

These components and the incorporating system resulted in a low cost system that has drastically improved dimensional stability and tooling cycle times.  The 4-5 days, cure cycle times for RTV components  has been reduced to a maximum of only 2 days, allowing us to meet tighter delivery schedules.

Do RTV molding yourself? Looking to have your own pressure pots? Contact GROWit and we can help you out! Contact us at sales@GROWit3D.com for more info.

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