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RTV Casting

RTV (room temperature vulcanizing) silicone is the most popular silicone rubber because of flex, and self releasing properties. It makes it ideal for short run moldings of cast duplicates. These duplicates can be used for functional testing or used in a production environment. RTV Casting is a cost effective solution where multiple quantities of the same part are required.

Stereolithography.com has a wide variety of Resin available, click here for available Urethane/Polyurethane Resins. Each resin has strengths and weakness. If you have a specific application planed for your prototype and you will find the guide below helpfully in choosing the correct resin. If you have any question or are unsure of the proper resin for the application you can ask your project manager to assist you in the selection of the proper material.

Click Here for a Step by Step Procedure of The RTV Casting Process

Master Pattern

Stereolithography models are the most commonly used master pattern for RTV Casting. To make a raw Stereolithography model into a master pattern you must first finish the model to a Class 3A Finish. All build lines are to be sanded and the parts are primed to create a smooth, presentation quality finish.

Diagram of SLA Machine

Pour RTV Mold

The finished master pattern is placed into the mold box and RTV Silicone rubber is poured on the master. The pour continues until the master pattern is completely encased in the RTV material. At this time the mold is set aside to complete the curing process


Pour RTV Mold

Finished RTV Mold

After 16 to 18 hours the RTV silicone mold will be fully cured. At this time the master part can be demolded. The life of the mold will typically last for up to 50 used depending on the material. Part Geometry and storage environment also play a large part in determining the usable life for the mold. For details on mold like contact your project manager with details on your specific project

Finished RTV Mold

Pour Urethane Duplicates

After the mold is fully cured and prepped for casting the selected urethane material is prepared. A wide selection of materials are available to mimic almost any material. For a short list of general material properties please consult your project manager or click here.


Pour Urthane Duplicates

Completed Cast Duplicates

Most urethane materials demold in 30 to 90 minutes but reach full cure in 24 hours. As soon as the duplicates are demolded another pure can take place. The time this process takes to complete is dependent on the material as well as the complexity of the mold. For this reason lead time can vary from the stated average lead time of 7 to 14 days. For a more accurate lead time please contact your project manager with details on your project.


Completed Cast Duplicates
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