What is Thixomolding?
- Thixomolding® is an environmentally friendly, high speed, net shape, Magnesium Injection Molding Process.
- In a single step, the process transforms room temperature magnesium chips, heated to a semi-solid slurry (a “thixotropic” mixture) inside a barrel and screw, into precision molded components.
What metals/alloys can be thixomolded?
- Several magnesium alloys can be used in thixomolding, the most common alloys being AZ91D and AM60B (see properties). Other alloys with higher creep resistance, at elevated temperatures, are also available for thixomolding, please contact us(link) for more information.
- In practice aluminum can NOT be thixomolded, as molten aluminum is extremely corrosive to nearly all types of steel. As a result thixomolding machine components have not been developed to thixomold aluminum.
What material properties can be expected?
- AZ91D magnesium (used for die-casting and thixomolding) has comparable properties to die-cast aluminum alloy, AL 380, and wrought magnesium alloy AZ31B (often used in machining). For more information on AZ91D and AM60B, please see our Technical Information page.
- Thixomolding produces higher density parts on average than die-casting (95-99% dense compared to 90-97% dense for die-casting.) This, primarily, results in more consistent strength and better elongation properties than die-casting.
How much does tooling cost compared to die-cast molds?
- Up front tooling costs for thixomolding are comparable to die-cast tooling costs. However, as thixomolding is at a lower temperature than die-casting, tool life can be greatly extended. Depending upon part complexity, non-cosmetic part tooling can be expected to last for at least 500K shots before replacement may be required.
What is the durability of magnesium?
- If magnesium is in an acidic environment, a protective coating will be necessary. If the part is not likely to be in such an environment, and/or is not cosmetic, cost savings can be realized by using the part without a coating, and a natural magnesium oxide skin will form on the surface of the part.
- Corrosion Rate Comparison Chart:
- Wear resistance for magnesium is low, so if high wear resistance is needed, a wear plate or durable coating (anodize, electroless nickel, PTFE, etc) should be used.
What type of coatings are available for magnesium parts?
- A variety of finishes and coating systems can be applied including paint, e-coat, electro-less nickel, chrome electroplating and a number of other options. Please contact us for more information regarding part coatings.
Are magnesium parts/is Thixomolding safe?
- The Thixomolding process, and magnesium parts are generally very safe. AZ91D has an ignition temperature of approximately 875°F (468°C), which is difficult to reach and maintain on a standard part due to magnesium’s high heat conductivity. During the thixomolding process, inert gas (argon) is fed into the feed throat to blanket the magnesium chips and prevent oxidation within the barrel or feed area of the thixomolding machine.
- However, magnesium shavings or powder, such as those generated by machining can be dangerous and need to be handled with proper precautions. Please see our Technical Information page and do NOT attempt to machine magnesium without taking all necessary safety precautions.
- Magnesium fines can react with water or acids to produce hydrogen gas as shown below with water (hydrogen gas is explosive even at low concentrations in air):
How can I reduce part cost/lead time with Thixomolding?
- Great question! The thixomolding process has several cost advantages over magnesium die-casting, please see our “Advantages” page for more information.
- Also, be sure of your tolerancing scheme and geometry layout. Thixoforming is capable of precision tolerancing (link) as-molded, including excellent flatness and molding bearing bores net shape. However, extremely tight tolerances and/or undercuts will generally require machining, adding cost to your part.
- Your lead time for a firm quote can be shortened if you are able to supply us with a 3D model with draft applied for molding and a drawing referencing all tolerancing, Critical-to-Function (CTF) dimensions, any coating or other part and quality requirements.
- We are certainly able to work with you on adding draft to your 3D model for moldability, but it will add to the time required for a firm quote.
- Please contact us (link) with any other questions.
Why should I use Thixoforming LLC for my product?
- The team at Thixoforming has a combined experience of nearly 100 yrs in the magnesium and Thixomolding industries. Thixoforming is a mature company, started in 1997, and has worked with companies including GM, Black and Decker, Chrysler, Remington, Rockwell Automation, L3 Brashears, Trek and many others on projects ranging from simple, low-volume jobs to complex, high volume parts.
- Our team has the knowledge, connections and talent to make your project a success. If you are not sure if thixomolding is the right solution, we will work with you to determine if it is, and if it is not we will certainly help guide you in the right direction to turn your idea into reality.