Frequently Asked Questions about the foamcast Process
foamcast 1. What metals can be poured in the foamcast lost foam casting process?
All ferrous and non-ferrous materials can be successfully cast using the foamcast process.
2. What size range of parts can be produced by the foamcast process?
foamcast process castings can be produced in most all metals from a fraction of a Kilogram up to several TONS. Slightly more advanced techniques are used for very large castings.
3. What “as-cast” tolerances can be expected?
Typically, a linear tolerance of +/- .05 mm is standard for the foamcast lost foam casting process. This tolerance will vary depending on part size, complexity and geometry. Subsequent straightening or coining procedures will often enable even tighter tolerances to be held on critical dimensions. A targeted effort to produce a perfect foam pattern results in a foamcast lost foam casting process casting that substantially reduces or completely eliminates previous machining requirements.
4. What type of surface finish can be achieved?
Because a permeable refractory coating is applied around the smooth foam pattern, the resultant finish is excellent. Each casting facility is different, but generally foamcast process castings have a surface finish within the 60-250 RMS range. If surface finish, due to cosmetic requirements, is a critical issue then surfaces can be targeted to maintain an exceptionally smooth finish.
5. What is the cost of using the foamcast - lost foam casting process?
foamcast process castings are generally more expensive than forged parts, or parts made by other casting processes. The value inherent in the foamcast process versus other processes is seen in tighter tolerances, weight reduction and as-cast features which all results in less machining and cleanup time. Many castings that require milling, turning, drilling and grinding can be made in the foamcast process with only 5-8mm of machine stock. It is imperative that the features to be cast are discussed by all parties to determine the net finished product cost.
6. What quantities need to be made to make the foamcast lost foam casting process practical?
The answer, simply, is not as many as you would think. Tooling amortization is a key factor in this determination. Potential overall savings for your application will aid in your decision. Generally, 500-1000 pieces per year is the minimum production run to be economical. Prototyping runs, however, may be as few as 3-5 pieces for Fabricated Foam patterns or 20-100 pieces for Quick-Cut CNC machined aluminum tooling.
7. What about casting porosity and shrinkage problems?
foamcast process castings are used for many critical applications, including engine heads, marine motors, high-pressure pumps and valves. X-ray and soundness testing on foamcast process castings shows characteristics comparable to other casting processes.
8. What type of tooling is required and at what cost?
Typically, tooling is composed of a split-cavity machined aluminum die that is the negative mold from which the foam pattern is produced. The tooling is highly specialized and must be constructed by experienced tooling manufacturers familiar with the requirements of the foam molders and foundries. Most tooling for foamcast process patterns will compare favorably with permanent and die cast tooling. Prototype and simple tools may be in the few thousand Rupees range while high-end tooling for complex or very large parts can be in the several Lack Rupees range. As a result of the materials used and the process stresses, foamcast process tools can be expected to have 3 to 4 times the cycle life of permanent mold or die casting tools.
9. What lead times can be expected when ordering a Lost Foam casting?
As with all processes, lead times vary greatly depending on part complexity. Generally, 8 to 16 weeks is typical for completed tooling and first castings produced. After casting approval, 6 to 12 weeks is typical for production run start-up. Rapid prototyping methods can produce castings in as little as 2 to 3 weeks.
Note: The information provided above is of a general nature and is intended to provide initial guidelines for process consideration. As with all processes, each project will face advantages and disadvantages during design and production. If you have more specific questions for a project that you are considering, please contact us we will be happy to discuss your project with you.
Non-proprietary terms that have been used to describe similar processes include: cavityless casting, evaporative foam casting, foam vaporization casting, lost pattern casting, the castral process, expanded polystyrene molding, EPC, Evaporative Pattern Casting,LFT,Lost Foam Technology,Expendable Pattern Casting,lostfoam,shellfoamcast, etc.