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Investment Castings

Frequently Asked Questions

What is an Investment Casting?

Investment casting is an industrial process based on and also called lost-wax casting, one of the oldest known metal-forming techniques.[1] From 5,000 years ago, when beeswax formed the pattern, to today´s high-technology waxes, refractory materials and specialist alloys, the castings allow the production of components with accuracy, repeatability, versatility and integrity in a variety of metals and high-performance alloys. Lost foam casting is a modern form of investment casting that eliminates certain steps in the process.

The process is generally used for small castings, but has been used to produce complete aircraft door frames, steel castings of up to 300 kg (660 lbs) and aluminium castings of up to 30 kg (66 lbs). It is generally more expensive per unit than die casting or sand casting, but has lower equipment costs. It can produce complicated shapes that would be difficult or impossible with die casting, yet like that process, it requires little surface finishing and only minor machining.

What tolerances can Thompson Investment Casting hold?

We typically quote a tolerance of +/- .005 per inch with a surface finish of 125 RMS or better.

Why would I use an Investment Casting?

An Investment Casting offers:

  • Design Freedom
  • Near net shape
  • Fine detail
  • Excellent mechanical properties
What alloys does Thompson Investment Casting pour?
  • Stainless Steels
    • Chromium-Nickel Stainless Steel
    • Heat Treatable Chromium Stainless Steel
    • Precipitation Hardening Stainless Steel Alloys
    • Heat and Corrosion Resistant Stainless Steel Alloys
  • Carbon and Low Alloy Steels
  • Tool Steels
  • Copper
  • Copper Alloys
Does Thompson Investment Casting pour any other alloys?

We do cast some specialty and other alloys upon request.

What are Thompson Investment Casting's size limitations?

At Thompson Investment Casting our size capability ranges from a fraction of an ounce up to about 25 lbs actual casting weight. The actual size limitation would be approximately 18 inches in length or width. Wall thickness can be achieved as thin as .020 using our specialized vacuum assist process.

What are the advantages of Investment Casting?
  • Investment Casting offers low tooling costs compared to other processes
  • Investment Casting has the ability to achieve near net shapes in the casting
  • Investment Casting can achieve close tolerances
  • Investment Castings have a smoother surface finish as compared other casting
  • Investment Casting offers many alloy options
How does Investment Casting compare to the following processes?
  • Sand Casting
    • Investment Casting has improved surface finish, more precise, tighter tolerances, greater design capability and greater alloy choices.
  • Forging
    • Investment Casting allows for greater design freedom equating to more complex geometries.
  • MIM
    • Investment Casting has lower tooling costs, is capable of producing larger parts, has lower alloy costs and can economically produce smaller run quantities.
  • Machining
    • Investment Casting offers material and labor savings for each required part
What can I expect for a lead time for Investment Castings?

Samples-----------2 weeks
Production--------4-6 weeks

Please contact us for a detailed quotation.

How can I be certain that Investment Casting is the correct process for my product?

A Rapid Prototype process can be implemented which will be a low risk opportunity to prove your design using Investment Casting. This will provide you and your company an Investment Casting for your testing and evaluation. Often a cast prototype can be produced in 2 weeks.

Can Thompson Investment supply parts complete to print?

Yes we can provide

  • Machining
  • Heat Treatment
  • Metal Finishing
  • Testing
  • Certifications

41 Old Dover Rd. • Rochester NH 03801

Rochester NH Web Site Design & Development
Contact Info
Call 603.330.8670
Fax 603.332.8942
[email protected]

Thompson Investment Casting can supply your company's investment castings
in the as-cast condition or finish to the print in the many different grades of steel.