The Importance Of Lead Screws

While you are moving in the industry circle, you may sometimes hear the words “power screw” or “translation screw”. These are just simply other names for lead screws. They are just controlling panels or levers that are used to transform rotary movements into linear movements.

What Are Lead Screws?

Lead screws which are also available as customized lead screws are bars of threaded metal along with a threaded nut. This nut is in direct contact with the screw. And this contact is the reason why sliding friction is generated as against rolling friction. The rotational motion will help to turn the screw whose nut will move in a linear direction. This is how the conversion of rotary motion to linear motion happens.

Since the screw shaft and the nut move directly against each other and on a bigger contact area, the energy loss is higher due to the production of friction. But the modern stainless steel customized lead screws are so evolving that their friction minimizes.

The Lead Screw Components

There are three major components in a lead screw. They are:

• Screw shaft – It is a cylindrical rod which has either a single or a series of grooves. These grooves run helically around the entire length and are also known as the external thread.

• Thread – The thread of the screw is the part that is responsible for the rotary motion getting converted into a linear motion while the screw shaft and the nut slide against each other.

• Nut – The nut of the lead screw is the cylindrical section whose thread is on the inner side as against the external thread of the screw shaft. Both threads will have to match each other.

Mode Of Operation Of Lead Screws

Lead screws can operate in two ways. One mode of operation allows the screw shaft or the nut to rotate and move linearly. But the component is fixed. This mode of operation is seen in helical pairs and printers. The other mode of operation is either the nut or the screw shaft rotates but the movement is not in a linear direction. These can be seen in lathes and presses.

The Design Aspects Of The Lead Screw

A lead screw will have the following design aspects:

• Minor diameter which is the smallest diameter. It is said to be the distance between the two opposite roots in the screw shaft. In the nut, it is the distance between the two opposite crests.

• Crest is that design aspect which is found in the external screw. It is the raised helical structure in the screw shaft and the depressed helical structure in the nut or the internal thread.

• Root is the depressed helical structure in the screw shaft while it becomes the raised helical structure in the internal thread or the nut.

• Thread depth is the root-to-crest distance measured radially.

• The flank surface connects the root to the crest.

• Pitch diameter is the concentric diameter that is found halfway between the major and minor diameters.

• Pitch talks about the axial distance between the adjacent threads.

The Different Types Of Threads In Lead Screws

Lead screws can be of different types of threads which are as follows:

• Square thread

• Acme thread

• Buttress thread

• Thread rolling

• Thread whirling

The Materials From Which Lead Screws Are Manufactured From

The metal of customized lead screws will greatly affect their longevity and its efficiency also. The wear of the screw will also be dependent on its material of construction. It is the metal which is the deciding factor of the coefficient of friction between the mating surfaces of the screw shaft and the nut.

So while selecting the material whether it is a stainless steel customized lead screw or any other screw there has to be exercised precaution. The purpose of the screw has to be taken into consideration before selecting the material.

But lead screws can be manufactured from metals like stainless steel, carbon steel, titanium, aluminium, bronze or even plastic. But hard materials must be avoided at all costs as they will proffer to its wearing out factor markedly. Whatever metal is chosen does not matter as long as the screw and the nut are compatible with each other.

Properties Of Stainless Steel Customize Lead Screws

The first property is that the metal of the screw and the nut must be compatible with each other or else they will not serve the purpose. But the other properties include its high compressive and tensile strength, resistance to fatigue, rigidity, anti-corrosive and resistance to all chemicals. They are thermal resistant because of the coating that is given to them after the manufacturing procedure is completed.

If a threaded screw is coated accordingly, then they require no lubrication to ensure its longevity. And taking adequate precautions also makes it suitable to withstand all weather conditions that they are exposed to.

Factors To Consider Before Buying Lead Screws

There are many deciding factors that can lead to the best lead screw be they customized or the normal ones found in the market. Taken into consideration the best screws can be decided on. Here are those factors for you to consider on:

• PV rating

• End fixity

• Critical speed

• Buckling load

• Lead accuracy

Benefits Of Lead Screws

Lead screws definitely have an advantage or else why will they be available in the market. The advantages are as follows:

• Lead screws are very cost-effective items which can also be very easily manufactured. It is very beneficial for applications that have intermittent, low speed and light to medium weight.

• All vertical applications can use these screws

• They can self-lock and thus require no braking and if the material has a high coefficient of friction then it is all the more better for the purpose of locking

• They are very compact in size due to the less number of parts

• In operation they are noiseless

• The lubricant coating makes it self-lubricating which means external lubrication is not required

Conclusion

Lead screws are available in all sizes as per the requirement. They have a wide variety of applications as in printers, disc drives, robots, lifting equipment, lathes, vices, jacks, CNC machines, the medical industry and a whole lot of other applications. Thus the importance of the lead screws cannot be overlooked.