Prototype Sand Castings in Gray and Ductile Iron

Making sand cast prototypes of gray and ductile iron is driven by the fabrication of the foundry pattern. In many cases, a foundry pattern made in wood or castable urethane using traditional pattern making techniques is the quickest and least expensive way to make prototype castings. The wood pattern is designed and built all in one step by the master pattern maker and is durable enough to make 1000’s of castings if the prototype goes into production. OK Foundry optimizes the traditional pattern design for speed and cost when only a few castings are required, and our manual green sand molding and no bake cope and drag line can quickly mold and pour prototype castings from 1 to 700 lbs. with short leadtimes.

For many of our OEM casting customers, prototype castings are the rule instead of the exception. New machines are built directly from castings, skipping the step of steel weldments for prototypes and establishing production tooling from the outset. With traditional wood patterns, design changes to the casting are easily made after prototype evaluation and prototype tooling is re-used for production volumes.

Fused Deposition Modeling for Rapid Pattern Fabrication

Most new castings are designed with 3D parametric solid modeling software and the resulting solid model of the casting can be used to print foundry pattern components. When 3D printing is possible, the pattern making time can be drastically reduced by avoiding manual layout of intricate details or modeling of complex shapes. In some cases the printed model is used directly as a foundry pattern element and in others the printed model serves as a master pattern for pattern or corebox fabrication.

RedEye by Stratasys is a service bureau that specializes in Fused Deposition Modeling (FDM) from 3D CAD data and is used by OK Foundry to print pattern components in ABS plastic. RedEye’s Overnite Build Service will print a part in ABS plastic overnite from a compatible CAD file. The ABS plastic parts are durable enough to be used as pattern components in green sand matchplate patterns or no bake cope and drag patterns. When appropriate, a FDM built model by RedEye is absolutely the fastest way to make a foundry pattern.

Patternless Casting for Complex Castings and Rapid Turnaround

ProMetal RCT offers the most advanced technology available for gray and ductile iron prototype castings. By printing a sand mold or core directly from CAD using a resin bonded sand system, ProMetal RCT can build no bake molds for complex castings including very thin sections and backdraft features for patternless casting. In some cases the ProMetal process can make molds that would be nearly impossible to make using traditional techniques.

The ProMetal process is also ideal for castings where engineering analysis of mold filling and solidification are required. The engineering time pays for itself by avoiding expensive bad castings due to mis-runs or shrink porosity.

In some applications the ProMetal process is used to print the complicated cores for internal passages or other features and traditional no-bake molding is used to form the mother mold and crude geometry. This rationalizes the total cost of the mold by minimizing the build volume of the ProMetal part.