THT Presses, Inc.
Leading Manufacturer of Rotor Die Casting Machinery and Equipment
Sub-Liquidus Casting
What Is Sub-Liquidus Casting?
SLC is a slurry-based semi-solid metal process that uses conventional foundry feedstock and can reuse in-plant run-around. THT introduced the process to capture the shape, detail, and dimensional benefits associated with semi-solid manufacturing while reducing the cost and alloy limitations often tied to billet-based SSM routes.
Sub-Liquidus Casting, or SLC, is THT Presses' approach to semi-solid metal casting. Instead of relying on premium billet that must be prepared outside the machine, SLC develops a controlled slurry during the normal casting cycle using grain-refined foundry melt, tight temperature control, and cooling in the shot sleeve.
The result is a largely globular semi-solid structure that can flow with lower turbulence, reduced gas entrapment, and strong part integrity while still supporting near-net-shape production, thin sections, multiple cavities, and heat-treatable alloys.
- Target solid fraction entering the die cavity: 40 to 60%
- Lower thermal input to the die: about 50% less, as reported in the source presentation
- Potential tool life improvement: 2 to 5 times versus die or squeeze approaches
- Average A356 T-6 UTS reported for SLC knuckles: 310 MPa
Why it was developed
Traditional billet-based semi-solid casting can be limited by feedstock cost, alloy availability, and the need to reprocess internal run-around back into billet. SLC was developed to preserve the benefits of semi-solid casting while using normal foundry alloys and creating slurry inside the production cycle.
Core idea: Create the right semi-solid structure at the machine, at the right temperature, in the right amount, and send only the most suitable material into the die cavity
What engineers value most
- Near-net-shape parts with reduced machining
- Capability for thin or thick cast wall sections
- Good detail, surface finish, and dimensional control
- High-integrity castings that can be heat treated
- Compatibility with primary alloys, secondary alloys, and selected MMC applications
Sub-Liquidus Casting (SLC)
Learn how THT’s Sub-Liquidus Casting (SLC) process uses a controlled semi-solid slurry approach to produce near-net-shape, high-integrity castings with fast cycle times, longer tool life, and excellent mechanical performance. This presentation covers the SLC process concept, key operating requirements, alloy considerations, and real-world test data showing how SLC can help reduce machining while producing sound, heat-treatable parts for demanding applications.