Steel shell, damped core
Filled Weldment Machine Bases
A steel design that fails a vibration target does not have to become a casting. Fill the shell with a damping compound and keep the fast lead time and easy design changes of a weldment. We match your drawing to fabricators in Vietnam that build the shell and have a fill route.
We are a sourcing service, not a foundry or a fabrication shop. You pay the fabricator you choose, nothing to us. Reply within 24 business hours.
What it is
A filled weldment is built exactly like a plain weldment, then the cavities are filled with a damping compound: mineral aggregate, polymer or concrete, depending on the supplier. The fill adds mass and damping and evens out short thermal spikes, so it is the cheapest way to add damping to a steel design. Damping is good to very good, against the lowest of the four for bare steel.
Stiffness still comes from the shell; the fill adds little to it. The shell is as easy to change as any weldment, but once the fill design is set the cavities are awkward to change, and the core is not repairable. The compound is proprietary to the supplier and not covered by a casting or concrete standard, so ask for its cured properties directly.
Where it fits
- A welded design that rings or chatters and needs mass and damping without a new construction
- Machines in moderate volume where a casting pattern is not justified
- Cases where the shell geometry may still evolve before the fill is frozen
Where it does not
- Fine-finishing and metrology machines that need the very highest damping: a full mineral cast goes further
- Designs where weight must stay low
- Anything needing the core to be inspected or repaired later
Process
How it is made
- Steel shell built exactly as a plain weldment
- Cavity filled with a damping compound: mineral aggregate, polymer or concrete, depending on supplier
- Fill cured, in some formulations for several weeks
- Final machining of the shell's reference faces
Standards
What governs it
ISO 13920, ISO 5817 (shell only), ISO 1101.
Each is explained in the standards index, including the one that is most often cited where a different one was meant. Themanufacturing technologies page shows the stages side by side with the other constructions.
Before you ask for a quote
What to put in the RFQ
Typical ranges for this construction, and what to state so two quotes can be compared. Ranges are not promises: they depend on the shop and the part.
| Item | Typical | Say in the RFQ |
|---|---|---|
| Shell | As a plain weldment: S235 / S355, ISO 13920 class B usual for machine frames, stress relieved. | The shell drawing with ISO 13920 and ISO 5817 stated, as for a welded base. |
| Fill compound | Mineral, polymer or concrete, supplier's own formulation. Not covered by a casting or concrete standard. | The compound, the cured density and damping data you rely on, in writing. |
| Fill and vent openings | The shell needs openings sized and placed so the cavity fills without trapped air. | Where the openings go and who designs them. Agree it before the shell is welded. |
| Cure | In some formulations several weeks before final machining. | Cure time and the date you need the first unit. |
| Machined geometry | Reference faces machined after the fill has cured. Flatness 0.02 - 0.10 mm over a metre is the usual band. | Flatness, parallelism and squareness per surface, with the datum scheme. |
| Weight | Heavier than the bare shell by the weight of the fill. | Finished weight with fill, lifting points and the crate requirement. |
The full checklist is in the RFQ checklist guide, and the seven things that move the price are on the home page.
Questions
Is a filled weldment as good as epoxy granite?
For damping, no. Mineral cast has the highest of the constructions. A filled weldment sits between bare steel and mineral cast, and keeps the speed and design flexibility of a weldment.
What do you fill it with?
It depends on the supplier: mineral aggregate, polymer or concrete. The compound is proprietary, so ask for the cured properties directly instead of assuming a grade.
Does the fill make the base stiffer?
Very little. Stiffness comes from the shell. The fill adds mass and damping. If stiffness is the problem, the rib design and the section matter more than the core.
Can the base be repaired?
The shell can, readily. The core cannot be repaired. A damaged fill is replaced with the part.