Specialized Turning Blog

Solving Bulge and Finish Issues when Machining Inconel

Posted by Chip Holm on Aug 20, 2020 4:00:59 PM

Avoiding Timely and Expensive Problems

If you are in an industry that requires equipment to work in extreme heat environments— aerospace, military, chemical, petrochemical, nuclear, etc.—you probably use inconel for your parts and components. The various types of inconel are workhorse materials due to their weldability (718) while having high strength and toughness (625), corrosion (600) and oxidation (718) resistance. While they deliver high performance in environments that test most metals, this metal tests most machinery when forming it.

machining inconel    

Being a heat resistant alloy, inconel can create machining problems for tooling and part geometry. Time-tested procedures are often upset by the alloy, even on repeat jobs. As an example, this can cause bulge deformities and finishing inconsistencies, create calibration and tolerance issues, affect quality, and ultimately slow down production. To avoid this, each part requires careful process planning.

Specialized Turning manufactures a thin wall diaphragm that requires a .0045” wall thickness across a .265” span from heat-treated inconel 718. It’s important for the wall to flex so that accurate readings can be measured from the instrumentation that the part supports. Bulging from heat generated from the machining operation would cause the face of the diaphragm to bulge—this bulging would vary from part to part and create variation in the product.

Post machining the surface of the face would require sanding and polishing to create a uniform surface across the part. This would also add heat to this very thin wall and create an inconsistent finish across the face of the part. This inconsistency would also increase the variation of the instruments’ readings.

We set out to find solutions to avoid these complications. By making modifications and creating a proprietary process, Specialized Turning was able to remove this bulging and post-process finishing, creating a more consistent and high-quality part for the customer. We put our years of expertise in machining inconel alloys at work for your unique part and component applications.

While each type of inconel has its own intricacies, we match state-of-the-art tooling geometries and coatings to ensure the most economical stock removal rates at the highest speeds possible for economical machining.

 Let’s talk about your inconel needs. We’d love to get the conversation started. Contact us today!



Topics: Inconel