Identifying Stainless Steel
Stainless steel is often specified for engineering projects due to its combination of strength and corrosion resistance. However, various grades of stainless steel are available—each with its characteristics and costs, so it's essential to make the right choice for your application.
The chromium alloy gives stainless steel its best-known advantage - high corrosion resistance. The chrome component creates the corrosion-resistant chromium oxide protective layer and contributes to its hardness, making it highly robust and resistant to impact. However, its relative hardness makes it more challenging to machine than mild steel, which means careful selection of your supplier is required to ensure optimum product quality and accuracy.
What are the main types of stainless steel for parts?
Type 304 is the most common type of stainless steel for component parts. It comprises up to 20 percent chromium, enhancing its corrosion resistance. It's often used in areas that are mildly corrosive or that require only an occasional washdown, such as handles or hinges. For this reason, it's also a more economical choice. Type 303 has similar properties but slightly improved machinability when very low tolerances are required but with marginally lower durability.
The highest quality stainless steel generally used for standard parts and components is Type 316. Its added molybdenum component makes it highly resistant to corrosion and pitting, the effects of which would create a less hygienic environment and accelerate corrosion. Known as 'food grade' (though it's also the first choice in the marine industry), 316 can endure regular chemical washdown or high salinity environments. While Types 303/4 steels should only be specified for certain conditions, Type 316 could be widely used for any application. These characteristics make it more expensive, although the difference between 304 and 316 has reduced over time.
Growing range of stainless steel components
The range of stainless steel components that WDS provides continues to grow due to increasing demand across wider industries and applications. Hand Knobs, for example, are ubiquitous throughout the industry, including food and beverage, marine, and also for machine parts. New to the WDS range includes a T Knob with threaded stem as well as a Four-spoke Threaded Hand Knob, both in 316 stainless steel. While stainless steel is often selected for its shine, the new threaded hand knob is also available in 316 with a matt finish, usually chosen to hide fingerprints and maintain the most hygienic appearance.
Another new addition to stainless steel is the Handwheel. Handwheels are often provided in aluminium, which can be suitable even for outdoor use if safety, hygiene or regulations allow. However, the new 316 stainless steel Handwheel will last far longer and is chosen for use in corrosive environments, such as marine applications. Small crafts to superyachts use WDS components and not only does 316 stainless steel provide the anti-corrosivity required, its aesthetic appeal is also more popular in the market.
A cam action indexing plunger is now available in stainless steel. It is used as a fixing on a machine when indexing a range of motion or series of positions. Indexing plungers and bolts are generally manufactured in Type 304, which provides adequate resilience even if they are not required to face the full rigours of a daily washdown.
Similarly, Castor Wheels used in food manufacture and preparation must meet the necessary hygiene standards but aren't required to withstand full washdown. Therefore, a stainless steel Type 304 frame combined with a nylon wheel is suitable. On the same principle, Levelling Feet with up to 50 degrees of angle tilt is also available in a 304 stainless steel stem. They can be fitted with an anti-microbial polypropylene base.
Alternatively, an example of the higher 316 grade being necessary for the food and beverage industry is on Gas Struts, precisely because of the essential nature of a regular washdown. These applications are used on food service hatches, mobile catering vans, and ventilation grilles, and they face regular contact with food and grease splashes. A regular washdown is needed for hygiene standards, and Type 316 stainless steel is required to withstand corrosivity.
Other WDS stainless steel products include gas Rivets, clamping handles, hinges, and detent pins.
