Ti-5553... Heard of ‘Alpha-Case’ Before?

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Ti-5553... Heard of ‘Alpha-Case’ Before?

How’s Cutting Ti-5553 Been for You? Heard of ‘Alpha-Case’ Before?

Evidently, there is a titanium-specific phenomenon known as “alpha-case” that may lead to cracking and eventual component failure if it’s not removed.

What is it? Dull cutters and overly aggressive machining parameters can generate enough heat to produce an oxidized layer.

What’s the fix? Experts Better MRO spoke to experts that say machinists must adhere to customer-approved process plans and not change to a different brand or style of cutting tool—or even change feeds and speeds significantly—without first running those changes up the engineering flagpole. Read our full coverage on Ti-5553 here.

With this constraint in mind, any shop new to beta titanium should set aside plenty of time for process development and cutting-tool selection upfront, as there will probably be few opportunities for changing either once the customer has signed off on the first article.

“If the process sheet says to change a tool at 10 pieces, then don’t try for 15,” says Jon Paggett, director of coating development at Kyocera Hardcoating Technologies, who also suggested using a heat-resistant but lubricious tool coating to help reduce the coefficient of friction.

Have you dealt with it before? What has it been like for you? 


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