A lead screw is a fundamental mechanical component designed for power transmission and precision linear motion.Its core structure consists of a threaded screw shaft and a matching nut.The most prevalent thread standards are the metric Tr thread with a 30° thread angle(per DIN 103)and the imperial ACME thread with a 29° thread angle.

Lead Screw and Nut Materials Selection

• Lead Screw Materials:Common options include low-carbon steel,S45C,SS303,SS304,SS316,40Cr,and 9Cr18.

• Nut Materials:Primarily various copper alloys(brass,bronze,etc.)or engineering plastics(POM,PEEK,Nylon,etc.).

High load applications:Copper alloy nuts are essential,requiring adequate lubrication with grease.Low-Load/Low produce particle environments:Plastic nuts are ideal as they offer self-lubricating properties,enabling maintenance-free operation without grease.

Lead screw Surface Treatments

Lead screws can undergo various surface treatments to enhance performance and longevity:

• Black Oxide Coating:A cost-effective protective layer,commonly used on standard carbon steel S45C lead screw.

• Hard Chrome Plating: Applicable to all materials.Significantly increases surface hardness and dramatically extends service life.

• Teflon Coating:Substantially reduces the coefficient of friction between the screw and nut.Benefits include lower starting torque,reduced operational noise,and improved running stability.

Important Note:Wear is inevitable over time,potentially leading to coating degradation or loss.For corrosive environments,austenitic stainless steel is strongly recommended.

Lead Screw Manufacturing Processes

The machining process of lead screw is mainly cold rolling(cold extrusion),turning and grinding.

• Cold Rolling(Cold Forming):Cold Rolling is the use of a pair of rollers to extrude round steel into the desired threads to form a lead screw.Longer threads can be formed in one pass from longer round steel and truncated for use.This kind of leadscrew is characterized by high material density,high hardness and high finish.However,the thread rolling wheel debugging time is long,and it is not possible to make bi-directional lead screws.A specific mold is required to make the required thread specification.

• Machining (Turning):Turning process,according to the need,can be processed a variety of non-standard threads,such as,arc thread,29 ° tooth angle thread,30 ° tooth angle thread,etc.Bi-directional threads can also be produced.

• Grinding:The grinding process is to grind the required threads with a grinding wheel,which is a long and costly method and is generally used only when there is a special need.

Lead Screw Self-Locking Characteristics

The self-locking property of a thread is its ability to keep its position unchanged and prevent loosening when a force is applied.It is generally related to the coefficient of friction,spiral rise angle and so on.For lead screw,the larger the diameter,the smaller the lead,the better the self-locking property.Special attention is paid to the better the self-locking screw,the lower the transmission efficiency,so you need to make a choice according to the actual needs.The transmission efficiency of leadscrew is generally between 20% and 40%.The transmission efficiency of plastic nuts is generally 10% higher than that of copper alloy nuts.

Lead Screw Applications

Lead screws are versatile components suitable for both manual and electric actuation systems.Common uses include:

• Manual sluice valves

• Industrial automation equipment

• Electric windows and doors

• CNC lathes and machinery

• Linear positioning stages

• Medical devices

• Elevating mechanisms