Formlabs believes in the power of digital jewelry design to open new markets and creative horizons. We also understand that the transition to digital has to make life easier, not harder.

If you’ve struggled to directly cast resin in the past, or just can’t devote kiln cycles to a small volume of resin pieces, why give up on wax? Wax has been used as a casting pattern material for millennia, and for good reason. It’s easily formable, and is gently eliminated from the most fragile investment molds. Long before 3D printing, vulcanized rubber molds were a major leap in serial production, allowing investment casting to work at scale.

Formlabs’ Form 4 resin 3D printers plus High Temp Resin and General Purpose Resins plug into a tried and true vulcanized rubber molding process. Form 4 offers 99% print reliability, producing parts with sharp details and smooth surfaces. With Form 4, you can print parts for the precise casting of detailed casting, or 3D print mold masters. 3D printing mold masters is one of the easiest ways to add the benefits of digital proceses to your business while saving space with digital inventory, lowering labor costs, and enabling fast customization — all with the same reliable wax casting process.

In this whitepaper, you’ll learn when to use different mold products, and which ones are compatible with Formlabs resins.

A wide variety of rubber materials with different tear strengths are available. When selecting a material, consider if you need durability for mass production, or a delicate one-off. 

• Organic rubber is preferred for long lasting, high-use wax molds, and has the highest tear strength. Organic rubber is best matched with thicker master patterns, such as signet rings, which are able to resist distortion during vulcanization.
• Heat vulcanized silicone rubber is vulcanized at a wide range of temperatures, and has lower tear strength than organic rubber. Silicone molds can capture superior detail, but degrade somewhat more quickly than rubber over many wax injections.
• RTV silicone starts as a liquid, and cures into a flexible solid at room temperature. RTV is best suited for molding around delicate 3D printed masters which could break or deform under vulcanization pressure, but has the lowest tear strength and durability.

Formlabs General Purpose Resins (Black Resin, Grey Resin) and High Temp Resin are the recommended choice for vulcanized rubber molds. Castable Wax or True Cast Resin can also be used for RTV molding, if you already use it for direct resin casting.

Post-curing parts is a critical step for all forms of rubber and silicone molding, because it allows Formlabs resins, including General Purpose Resins, to reach their optimal strength and temperature resistance. Post-curing also neutralizes any remaining uncured resin on the surface of a pattern, which may interfere with vulcanization or silicone curing.

Mold release spray such as Castaldo Resin Release can help prevent resin patterns from adhering to RTV silicone. Apply mold release, and then use compressed air to remove excess.

When designs are 3D printed, master patterns can be more delicate and detailed. Specialized equipment will help you replicate the finest features regardless of design complexity.

VACUUM WAX INJECTOR

If injecting wax into designs with thin channels, Formlabs recommends a system with vacuum and mold clamping features. 

US/EU: Digital-Vacuum Wax Injection System 
APAC: Sanei Vacuum Wax Injector

VACUUM/PRESSURE CHAMBER

A vacuum chamber is used to eliminate bubbles in a mold, and is essential equipment for most RTV molding. 

US/EU: Vacuum Table

Form 4, alongside Castable Wax Resin, True Cast Resin, General Purpose Resins, and High Temp Resin, provide a versatile jewelry production toolkit that supports direct investment casting, fit testing, prototyping, and vulcanized rubber molding. By 3D printing mold masters, you can retain the reliable wax casting process you’re familiar with, while reaping the cost and time benefits of a digitized workflow.

For those looking to jump into digital jewelry workflows, True Cast Resin is formulated for reliable, precise casting of detailed patterns. It is a wax-filled material designed for precision casting of intricate jewelry and complex engineering components up to 5  mm thick. True Cast Resin is engineered for reliability, quality, and versatility. With low thermal expansion, minimal shrinkage, and 0.03% ash content, it delivers consistently excellent casting outcomes. 

Request a free sample part to evaluate Formlabs Resins for yourself or contact sales to learn more.