Stainless Steel Machining

Stainless steel is one of the most popular metals used for parts and components for demanding, high wear applications. It combines the strength of carbon steels with superior corrosion resistance, high wear resistance, heat resistance and low conductivity, making it an ideal material for parts and components in high wear, harsh environments.

Stainless steel alloys are ferrous alloys that contain a minimum of 10% chromium. The chromium forms a layer on the surface of the metal when exposed to oxygen that is impervious to water and air and is responsible for stainless steel’s superior resistance to corrosion, rust and chemicals, resistance to staining and shiny finish. Higher chromium content results in increased corrosion resistance. Stainless steel alloys used in the harshest environments can contain up to 26% chromium content. In addition, the protective chromium layer allows for easy cleaning and its heat resistance allows for repeated sanitizing. To prevent galling on joined parts, parts may be coated with dissimilar metals or lubricated.

Stainless steels are classified into three main groups – austenitic, ferritic and martensitic. Austenitic steels are the most popular alloys, accounting for over 70% of stainless steel production. They contain a minimum of 16% chromium and nickel or manganese to reduce brittleness. Austenitic steels include the 300 series, used in most parts and for sanitary applications. Ferritic alloys contain lower chromium and nickel content than austenitic alloys.Chromium content is between 10.5% and 27% and most of the ferritic alloys contain molybdenum. While easier to machine, they have reduced corrosion resistance. Martensitic alloys contain 12-14% chromium content and low levels of molybdenum, nickel and carbon. They are easier to machine than austenitic and ferritic alloys and exhibit high strength and toughness. Precipitation hardening martensitic alloys increases their corrosion resistance to levels comparable to austenitic alloys.

Machining

• Use low cutting speeds.

• Maintain high feed rates.

• Temperature is not affected by feed rate so much as by speed, and the highest feed rates consistent with good machining should be used.

• Use sharp tools and replace them at the first sign of wear. Dull tools cause work hardening and glazing of the metal surface.

• Large tools dissipate the heat generated during machining

• Cuts should be substantial enough to prevent the tool from riding the surface of the work to prevent work hardening.

• Never stop feeding while tool and work are in moving contact. Allowing a tool to dwell in moving contact causes work hardening.

• Coolants and lubricants are required to counteract the heat generated at the cutting edges of the tools

Usage

Stainless steel is used throughout industry for a wide variety of parts and components. These products are as diverse as fasteners, food service processing equipment, medical device components, aerospace and automotive motor parts and decorative architectural parts. Its high strength to weight ratio, ease of machining, high heat resistance, high wear properties and corrosion resistance allow stainless steel parts to high perform well in many applications.

Chucking Machine Products specializes in ultra-precision machined parts for the aerospace and defense industries. Some of the products we machine for our customers include:

• Engine and exhaust components that must perform well in high heat, high wear environments, such as fuel nozzles, gearheads and mountings

• Turbine blades, impellers and propellers that must be strong, lightweight and corrosion resistant

• Airframe and structural parts that require high strength and light weight properties, coupled with heat resistance and corrosion resistance

• Tubes and shafts for aircraft and missile motors and engines that require high heat resistance and anti-corrosive properties