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Machining of Inconel

A material often specialised for high temperature and high wear condition, Inconel is often referred to as a ‘hard’ and ‘exotic’ material, but what exactly is it? What are it’s applications and how do you machine it?

What is Inconel?

Inconel is a family of materials all with Nickel and Chromium at their base. There are a number of different grades but the most popular within engineering would probably be 718 and 625.

Key Attributes

Inconel is resistant to high temperatures and will retain tensile strength even up to 2000°F. This extreme temperature resistance has seen Inconel become the material of choice in many Heat Treatment operations in baskets and work holding tools. Alongside its ability to perform at elevated temperatures, Inconel can also operate in environments with rapid temperature changes whist retaining excellent resistance to oxidation.

Inconel also provides excellent corrosion resistance to a variety of sources. Inconel 625 provides excellent resistance to Hydrochloric, Sulfuric, Phosphoric and Nitric Acid. Inconel 718 primarily offers corrosion resistance to organic acids, Alkaline and saltwater. Inconel’s resistance to Sodium Chloride at varied temperatures make it ideal for marine and offshore environments.

Inconel is a hard and dense material and on Brinel Hardness tests, Inconel 625 measures 200 on the scale and aged 718 measuring 425.

Machining

Inconel is a very difficult machine due to the toughness of the material and the rapid work hardening that occurs. (Also known as Strain Hardening) This causes deformation of either the tool in use or the part itself. In some cases the Inconel’s outer layer will harden too quickly during machining which results in an imperfect shape. In order to get the best results it’s important to use slow but aggressive cuts and where you do have long, uninterrupted cuts to use ceramic cutting tools.

Outsource It

Where you may be unfamiliar with machining of Inconel it may be more cost and time effective to outsource your machining. The cost of Inconel is extremely high and so the potential of scrappage is an unwelcome one, especially where you are dealing with components that have intricate geometries or large surfaces. Bronte Precision have many years of experience of working with Inconel including the production of Pump Motors for the marine industry. We are ISO certified and serve the whole UK.