11.03.2022

About Fastener Materials
General

Fasteners are manufactured in a wide range of materials from common steel to titanium, plastic and other exotic materials. Many materials are further separated into different grades to describe specific alloy mixtures, hardening processes, etc. In addition, some materials are available with a variety of coatings or platings to enhance the corrosion resistance or alter the appearance of the fastener.

Fastener material can be important when choosing a fastener due to differences between materials in strength, brittleness, corrosion resistance, galvanic corrosion properties and, of course, cost.

When replacing fasteners, it is generally best to match what you are replacing. Replacing a bolt with a stronger one is not always safe. Harder bolts tend to be more brittle and may fail in specific applications. Also some equipment is designed so that the bolts will fail before more expensive or critical items are damaged. In some environments, such as salt water, galvanic corrosion must also be considered if changing fastener materials.

Materials

Stainless Steel

Stainless steel is an alloy of low carbon steel and chromium for enhanced corrosion characteristics. Stainless steel is highly corrosion resistant for the price. Because the anti-corrosive properties are inherent to the metal, it will not lose this resistance if scratched during installation or use.

It is a common misconception that stainless steel is stronger than regular steel. In fact, due to their low carbon content, many stainless steel alloys cannot be hardened through heat treatment. Therefore, when compared to regular steel, the stainless alloys used in bolts are slightly stronger than an un-hardened (grade 2) steel but significantly weaker than hardened steel fasteners. Unless great care is taken, stainless fasteners are susceptible to seizing up during installation, a phenomenon known as galling.

Most stainless steel fasteners are much less magnetic than regular steel fasteners though some grades will be slightly magnetic.

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.

What is a lead screw used for?

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 of Using Lead Screws

Lead screws have many advantages – some of these are;

High load-carrying capacity

Compact

Easy to design into a system

Minimal number of parts

Smooth operation

Quiet

Require little maintenance

As well as the above advantages, lead screws from Heason also have the following;

Competitively priced

Flexible configurations

Available in screw diameters as small as 6mm

Self-locking, therefore, do not require a braking system

Difference Between Nuts and Bolts
In this article, we will discuss the difference between nuts and bolts. The nuts and bolts are the types of fasteners that are used in every manufacturing industry to join two parts together. Here we will try to learn all the possible differences between nuts and bolts.

Difference between nuts and boltsWhat is Nut?

It is a type of fastener that has a threaded hole. It is used with the conjugation of a bolt. The two partners (i.e. nut and bolt) are held together by the combination of their thread frictions, slight stretching of the bolt and compression of the part to be joined together.

The nuts come with a different locking mechanism which prevents the loosening due to the vibration of the machine parts or the parts which they joined.

They are mostly having a circular cross-section.

The nuts have internal threads so that it can be easily tightened on the bolt.

The size of the nut is small as compared with the bolt.

The nuts experience compressive forces. It is the compressive stress that leads to its failure.

The various types of nuts are: Hex nut, Nylon insert lock nut, Jam nut, Nylon insert jam lock nut, Square nut, Cap nut, Acorn nut, T- nut, Kep nut, Castle nut, Wing nut, Flange nut, Slotted nut, Coupling nut, etc.

What is Bolt?

A Bolt is a threaded cylindrical rod which is used with a nut. It is used to join two pieces together with a nut. It is a type of fastener.

A bolt is externally threaded. It may be fully threaded or partially threaded.

The bolts are cylindrical in shape. They are the solid cylinders with a head. The solid cylindrical part is called the shank.

The size of the bolt is large as compared with the nut.

The bolts experiences tensile forces. It is the tensile stress that leads to its failure.

The various types of bolts are Anchor bolt, Carriage bolt, Elevator bolt, Flange bolt, Hanger bolt, Hexagon bolt/Tap bolt, Lag bolt, Machine bolt, Plow bolt, Sex bolt, Shoulder bolt, Square head bolt, Stud bolt, Timber bolt, T-head bolt, Toggle bolt, U-bolt, J-bolt, Eye bolts, etc.

Aluminum Sheet Products Versus Aluminum Plate
Today, aluminum materials make up 75 to 80 percent of a modern aircraft and aluminum has been used in that capacity since the birth of powered flight.

In fact, even before the Wright Brothers first successful flight in 1903, Count Ferdinand Zeppelin used aluminum to make the frames of his airship that flew for the first time in 1900. And a few years later, the famed brothers from Dayton built a lightweight aircraft engine using a cylinder block and other parts made with aluminum.

The reason for this is that aircraft requires building material that is inherently strong and lightweight.

And aluminum has fit the bill beautifully since the dawn of manned flight.

Because aluminum aerospace parts are about one third the weight of steel, which allows aircraft to carry more weight and be more fuel efficient than they could be if built with heavier material. In addition, the high corrosion resistance of aluminum is essential for aircraft safety.

Aluminum parts are made from a variety of alloys grades of material and of different methods of production. These different alloys and grades are used for particular aerospace applications.

Here are a few of the more common grades and uses:

2024 is typically used for cowls, aircraft skins, and common aircraft structures, as well as for repair and restoration. It is also the most common alloy used.

7075 is a high-strength alloy and used to strengthen aircraft structures. It is also one of the most common aviation industry grades after 2024.

5052 is an aluminum grade often used for fuel tanks because of its excellent moisture and corrosion resistance.

3003 grade aluminum sheet is commonly used for cowls and baffle plating.

While aluminum can be formed as blocks, rods, and bars, two of the most common forms used in the aerospace industry are sheets and plates.

Aluminum sheets and plates start with ingots of raw aluminum which are preheated before processing. Once the ingots are properly heated, the aluminum is fed into a breakdown mill and then formed into a thick sheet.

From here, the sheet is rolled repeatedly until it is reduced to a thickness of just a few inches. After the rolling process, the rolled aluminum sheet is wound into a coil and cooled by passing them through several cold rolling mills. The cold rolling of the aluminum sheet is the final step of the process.

As aluminum moves between rolls under pressure, it is reduced in thickness to create plate or sheets. Aluminum plate metal is .250 inches and thicker, while aluminum sheet is typically defined as a piece of metal that is less than .249 inches thick.

Aluminum plate is the most often used in the aerospace, transportation, and military industries for heavy-duty applications. A unique attribute of certain aluminum alloys is their ability to become stronger at extremely cold temperatures. Because of this, aluminum plate is used for the skin of spacecraft fuel tanks and jets, as well as storage tanks.

In addition, the high resistance to corrosion, its light weight, and its high strength, makes aluminum plate a common material for the structural sections of ships and railcars, as well as for military vehicle armor and even body armor..

Aluminum sheet and plate are widely used and in demand due to light weight, strength, high corrosion resistance, workability and versatility of aluminum alloys.

Lead Screws vs Ball Screws: It's All about the Application
Each type of actuator has its advantages and disadvantages. Before you can decide on what type of screw to use, you need to understand how the distinct characteristics of each match your specific application.

What are the advantages/disadvantages of lead screws?

Lead screws cost less.

Lead screws are self-locking and do not require a braking system.

Lead screws are better for vertical applications.

Lead screws are generally less efficient, requiring greater torque and a larger motor and drive.

Lead screws have higher friction and run a hotter temperature.

Most lead screws are not well suited to high throughput, high speed applications or those with continuous or long cycle times.

Lead screws need to be replaced more frequently.

What are the advantages/disadvantages of ball screws?

Ball screws require braking systems.

Ball screws can have problems with vertical applications.

Ball screws are more efficient, requiring less torque.

Ball screws have lower friction and run at cooler temperatures.

Ball screws require grease or oil lubrication to achieve design life.

Ball screws need to be replaced less frequently.

Ball screws are noisy.

Ball screws require braking mechanisms to eliminate backdriving.

Ball screws are more expensive than lead screws.

How does my application dictate which one to use?

Generally speaking, ball screws are better for applications that require smooth motion, efficiency, accuracy, precision, and prolonged continuous or high-speed movement. Traditional lead screws are more suitable for simple transfer applications for which speed, accuracy, precision, and rigidity are not as critical.

However, a new generation of precision lead screws—such as those offered by HELIX™ Linear Technologies—significantly increases lead screw accuracy. Using advanced thread-rolling processes and material composition technologies, HELIX offers precision engineering lead screws that are just as accurate and repeatable as ball screws. The primary question to ask yourself about your application is how critical is accuracy? If precision is a priority, you may want to choose a ball screw or a precision-engineered lead screw.

Of course, there are always trade-offs to be made depending on your application. In addition to materials, assembly design, and accuracy, important variables to consider include wobble error, noise, maintenance, efficiency, and longevity. In most cases, evaluating the load, accuracy, and lead for your application will most generally answer the question of ball screw vs. lead screw. If the loading of your application turns out to be too great for a lead screw, use a ball screw or a precision-engineered lead screw instead.

If you need help evaluating whether to use a lead screw or ball screw for your linear-motion application, contact us today.

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