Tuffalloy 4270 Series
Tuffalloy 4270 is a series of Liquid Molding Compounds with thermoplastic properties such as high impact, high heat distortion, and low viscosity. This unique chemistry developed by Hapco to meet today’s market demands for prototype and low production parts needs.
Most headforms used by Cadex Inc. are formed out of Magnesium K1a alloy. There are few (if any) thermosets for casting that will come close to matching the material properties of magnesium. The Tuffalloy resin has the highest tensile strength offered by Hapco Inc. and is recommended for the headform application. For a higher strength, fiberglass may be added to the resin mix and experimentation is required for this testing. Tuffalloy 4270 has a hardness shore of 84 D ± 5 which is slightly harder than a hardhat (physical comparison).
Tuffalloy 4270 is available in quart units or gallon units. A “unit” comes with the appropriate amount of both the resin and hardener. A quart unit contains a total of 4 lbs of material and costs $63.87 plus a $10 re-packaging fee since Hapco Inc. normally sells quart units by the case (6 units per case). A 1-gallon unit contains 16 lbs of material and costs $207.33.
The Hapco Inc. Customer Service Department is contacted via telephone at 877-729-4276.
The mold most likely need to be waxed and sprayed with a mold release, such as Grease-It 4 or 5.
Thermoplastic type properties
Fast cycle time
Excellent Physical Properties
1:1 Mix ratio
Pouring the Headform
Mix Part A (resin) and Part B (hardener) by hand and pour mixture into mold. Pour from one end so the material pushes air out as it fills the mold. The mix ratio of Tuffalloy 4270 (A:B) is 100:100 by volume and 100:85 by weight. If we do not plan to use the full amount in the containers, we will need to weigh out the correction proportion of each component. This material is very low viscosity and de-airs pretty well on its own, but without vacuum degassing or pressure casting we are likely to get some small air bubbles in the headform since mixing by hand will introduce a lot of air and gas into the material.
A pressure chamber would be the best option when casting the Tuffalloy 4270. Curing the headform at 60 – 80 psi would allow for a better headform. The pressure chamber will eliminate voids in the material that would otherwise be seen if the headform cured in an open room at room temperatures and pressure. Tuffalloy 4270 Series can be pressure cast, vacuum cast, or open cast.
Shrinkage is largely influenced by the following factors:
Mass (total volume and thickness)
Temperature of the material
Maximum temperature reached during the exotherm (reaction)
Temperature of mold
Thermal properties of the mold material (Insulator versus Conductive)