Stainless Steel Fasteners are, most importantly, corrosion resistant. They have an excellent life cycle, are environmentally friendly and are 100% Recyclable. They are also resistant to high heat as well as extremely cold temperatures making stainless steel fasteners the material of choice for almost any application!
What is Stainless Steel?
Stainless Steel is a generic term given to a large range of corrosion resistant steel alloys. Elements of these alloys can include chromium, nickel, iron, manganese, silicon, carbon, nitrogen, sulphur, phosphorous, molybdenum, titanium, niobium, copper, tungsten and vanadium. When the proportions are changed, the characteristics of the resultant alloy change.
Why is Stainless Steel corrosion resistant?
Stainless steel is a low carbon steel that contains 10.5% or more chromium by weight. Chromium gives the steel its anti-corrosion property by allowing the formulation of an invisible chromium-oxide film on its surface which is known as a passive layer. This layer or film can self-repair if damaged mechanically or chemically when it has available oxygen, even in small quantities. The corrosion resistance of stainless steel may be enhanced by increasing the chromium content together with the addition of other elements to the alloy such as nickel, molybdenum and titanium.
Can Stainless Steel corrode?
Yes it can! Stainless steel is corrosion-resistant but not corrosion-proof and corrosion can occur if the material is installed or handled incorrectly. The corrosion may be limited to visual damage only or could be as serious as functional loss of the alloy material through pitting or crevice corrosion. It follows that in these circumstances the many advantages of stainless steel alloys are lost. Corrosion can be the result of various factors but typically it is caused by a lack of available oxygen which prevents the formation of the natural and self-repairing barrier of chromium-oxide on the surface of stainless steel material. The use of tools and drills made from conventional steel during the installation of stainless steel fasteners may also lead to problems. Even the hardest of tools can produce debris that leaves minute steel particles on the stainless steel fastener surfaces or in pre-drilled holes. It is these particles that often rust when exposed to moisture or oxygen and can result in a stained or tarnished finish to the stainless steel material.
How can extraneous corrosion be prevented?
Keeping the surface of stainless steel clean and contaminant free is one of the best ways of preventing extraneous corrosion from occurring. Using appropriate sealant products during the installation of stainless steel fasteners located in damp or wet environments as well as tools made from stainless steel are also useful in preventing extraneous corrosion.
How many different types of Stainless Steel are available?
Because of the large number and combinations of elements used to make stainless steel alloys, the number of different types or grades is almost limitless.
How are Stainless Steels categorized?
Stainless steels can be found in four different categories: Austenitic (300 series), Martensitic (400 series), Precipitation Hardenable (17-4PH, 455), and Ferritic (430, 443).
What is the difference between these groups?
The main difference lies in the type of hardening.
What about Stainless Steel and magnetism?
Each stainless steel alloy shows different magnetic characteristics. Only the Austenitic (304, 316, 316L) stainless steels are largely non-magnetic but it is common for stainless steel fasteners to show a small degree of magnetism which is a result of work-hardening during the manufacturing process. All other stainless steel alloys are magnetic to some degree.
What is passivation?
Passivation is the removal of iron particles from the surface of stainless steel. The removal of iron particles facilitates the interaction of the chromium in the steel with oxygen which produces the formation of the passive chromium-oxide film layer. This thin and invisible layer protects material from further corrosion by its ability to self-repair. If the material is scratched and the passive film disrupted, more oxide will form and cover the exposed surface. For deep scratches, material can be manually passivated again.
What is a Lead Screw?
A lead screw is sometimes referred to as a “power screw” or a “translation screw”. They are used within motion control devices to transform rotary or turning movements into linear movements.
Lead screws are threaded bars of metal and a threaded nut which is in direct contact with the screw; this generates sliding friction as opposed to rolling friction from other alternative devices (such as a ball screw). Rotational motion will turn the screw, causing the nut to move along in a linear motion. This, therefore, converts the motion from rotary to linear.
They can be used for either vertical or horizontal movements and can use linear glides for support where necessary. They can be operated either manually or mortised depending on the application in hand.
Where the screw itself is generally constructed of stainless steel, the nut can be various materials depending on what is better suited for the application. Heavy-duty applications will require a metal nut whereas other applications may require a plastic one.
Lead screws are commonly used as a component within linear motion control systems. They are well suited to instrument grade applications such as;
Laboratory and life science equipment including DNA sampling
Fluid handling devices
Engraving
Rapid prototyping
Data storage
Inspection
Heavy lifting applications – a metallic nut must be used for this type of application
When selecting a lead screw, it is important to take into consideration the speed, thrust, accuracy and repeatability of the application. If you require assistance selecting a lead screw or would like to discuss your application please contact us.
Advantages and Disadvantages of metals commonly used in Manufacturing
Look around the factory floor and, as sure as day, a gleaming array of metallic instrumentation and machinery will be staring back at you. Were it not for some incredibly versatile metals, much of these tools, and the products and services that the Process Industry specialises in simply couldn't be produced on a mass industrial scale. PIF examines the advantages and disadvantages of several metals commonly used in manufacturing.
Advantages: The most abundant metal in the Earth's crust, Aluminium is relatively soft, durable, lightweight, ductile and malleable metal. It acts as a good thermal and electrical conductor and is also fairly corrosion resistant. Plus, it is theoretically 100% recyclable without any loss of its natural qualities and remarkably nontoxic.
Disadvantages: It's not particularly strong and is expensive compared to steel of the same strength.
Applications: Aluminium is almost always alloyed to improve its properties. It is commonly used in the transportation, construction and packaging industries.
Bronze
Advantages: Bronze is an alloy consisting mainly of copper but the addition of other metals (usually tin) produces an alloy much harder than plain copper. Bronze resists corrosion and metal fatigue better, and conducts heat and electricity, better than most steels.
Disadvantages: Bronzes are generally softer, weaker and more expensive than steel.
Applications: Bronze is widely used for springs, bearings, bushings, automobile transmission pilot bearings and is particularly common in the bearings of small electric motors.
Carbon Steel
Advantages: Carbon steel's main alloying constituent is carbon. Low carbon steel is the most common and cost effective form. It contains around 0.05–0.320% carbon and is malleable and ductile. Medium carbon steel contains between 0.30–0.59% carbon and balances ductility and strength with good wear resistance. High-carbon steel has 0.6–0.99% carbon content and is exceptionally strong, while ultra high carbon steel contains 1.0–2.0% carbon and can be tempered to great hardness.
Disadvantages: Low-carbon steels suffer from yield-point runout and mild steel has a relatively low tensile strength.
Applications: Medium carbon is used for large parts, forging and automotive components. High-carbon steel is used for springs and high-strength wires. Ultra high carbon steel is used for special purposes like knives, axles or punches.
What is a nut?
A nut is a mechanical fastener with a threaded hole. It is attached to a bolt, screw or stud to provide a clamping force and prevent axial movement. For example, a bolt is inserted through two parts, with aligned holes, and a nut is then screwed onto the bolt. The shaft of the bolt prevents radial movement of the parts, while the head of the bolt and the nut together prevent axial movement.
The most common type of nut is the hex nut. This has a hexagonal outer shape for the faces of tools to apply torque when fastening. To provide a secure fastening, this type of nut typically relies on torque being applied to generate an axial force. This axial force causes sufficient friction at the threads so as to prevent the nut from unscrewing. The force may act between the bolt head and the nut, causing compression of the parts being fastened. Alternatively, it may act between a pair of adjacent nuts, allowing parts to be fastened more loosely.
Thread-locking adhesive may also be applied to the threads of a nut to prevent it from working loose. Special locking nuts may also be used which work with devices such as pins, lockwire and nylon inserts to prevent loosening.
Older nuts were often manufactured with a simpler square head and this design is still sometimes used to enable increased torque to be applied using a spanner.
There are many more specialized types of nut
Cap nut: The hole is only accessible from one side with a smooth domed surface on the other side to prevent injury to persons.
Barrel nut: A cylindrical shape which can be inserted into a hole running perpendicular to the axis of the bolt.
Cage nut: A form of captive nut which can be attached to parts such as sheet metal, allowing bolts to be fastened in inaccessible spaces.
Two nuts tightened against each other to prevent loosening without compressing the parts being fastened.
Coupling nut: An elongated nut which allows two threaded shafts to be joined coaxially.
Flange nut: A hex nut with an increased diameter around the base, removing the need for a washer.
Knurled nut: A nut with a large textured diameter, designed to be hand tightened.
Swage nut: A nut which attaches itself to a sheet metal part when tightened, by swaging the material around the hole
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