SCREW-TECH, an established supplier of precision lead screws, offers a comprehensive selection including power, miniature, and high helix thread forms. These lead screws find applications across a broad range of industries, and with decades of experience, SCREW-TECH excels in providing the perfect linear product for an ever-expanding array of applications. With the ability to combine all lead screws with a variety of nuts, SCREW-TECH caters to a multitude of performance requirements. The advantage of an in-house machine shop ensures the swift delivery of lead screws and nut programs that are ready for seamless installation. SCREW-TECH's confidence in reverse engineering linear products becomes invaluable when original drawings are unavailable. This capability ensures viable solutions for various challenges. In addition to precision lead screws, SCREW-TECH offers a diverse range of related ancillary products such as support bearings, racks, splines, and more, providing customers with a complete solution that meets their specific needs, all at the right price. Combining the lead screws and nuts with a full range of linear guides and rails will provide load support to any linear mechanism. Offering excellent rigidity and parallelism during operation, the guides can be used in both vertical and horizontal planes. The whole linear program allows the supply of complete mechanical systems through knowledgeable staff. Among various types of lead screws used in mechanical systems, trapezoidal lead screws stand out as a popular choice. These screws feature a unique trapezoidal thread profile, which provides efficient linear motion and precise positioning in many applications. With their self-locking ability and excellent load-carrying capacity, trapezoidal lead screws are commonly utilized in industries such as manufacturing, automation, and robotics. Engineers and designers often rely on these reliable and durable components to convert rotary motion into linear movement with minimal backlash, ensuring smooth and accurate operations in diverse systems. Types of screw threads There are 3 basic ways to make the lead screw thread, namely rolling, whirling, and grinding. Each method has its advantages and disadvantages, so let’s look at each method individually. Lead screws can be found in many industries including Automation, Medical, Defence, and Transport applications, to name a few. Rolled The thread form is squeezed into the bar of material using dies under high force. This method produces a thread with a really good sliding surface finish, and the process is quick. As the rolling process compresses the material, it also superficially hardens the working area of the thread. The majority of our threads are rolled. The disadvantage of a rolled thread is that very high precision isn’t possible. Most rolled threads are 2G, with care we can roll most sizes to 3G, but 4G is too much for rolling. Whirled (Machined) The thread is machined rather than formed as it is in rolling. This means the thread is high accuracy but doesn’t have a great surface finish nor is it hardened. This thread (with a natural finish, i.e., uncoated) is not suitable for use with plastic nuts due to surface finish. Ground A very precise thread can be created in hardened materials, but you have a limited choice of sizes and thread forms. The process is also labor-intensive, which makes them a higher price and longer delivery time than the other methods. A ground thread is normally used where accuracy is of utmost importance. Screw Materials As standard, most rolled lead screws are made from 300 series Stainless Steel. These materials form well, give a great surface finish, and have good corrosion resistance. For a ground screw, something like 440C or 17-4pH works well as it is a grade of stainless that can achieve sufficient hardness. But these types of Stainless don’t have the corrosion resistance of 300 series. Customers like the thought of 440C or 17-4pH because of its hardness, but unless it’s a ground thread, it is difficult to machine and doesn’t leave a great surface finish. Nut Materials Several types of materials can be used for the lead screw nut. The material you choose for the nut depends on the application. Broadly speaking, you have 3 nut materials: Steel, Copper Alloy, or Polymer (Plastic). Steel - Used for high loads at low speed. Copper Alloy (Bronze) - Bronze nuts are very popular for lead screws. There is a vast choice of bronzes to choose from, such as Leaded (Pb) Bronze, SAE660, or Sigma 7 Bronze, which are also popular choices. (The Pb in the material reduces the sliding friction between nut and screw). Materials with higher strength include Tin Bronzes (PB102) and Alu Bronzes (CA104), but these have more friction than the Pb Bronze, are less tolerant of lack of alignment, lubrication, and shock loads. Polymers - The number of plastics suitable for making lead screw nuts is almost endless; however, there are several that have become the industry norm. Plastics are useful because they are mainly low friction and require little if any lubrication. Lead Screw Coating Various coatings can be applied to the screw to reduce friction of the mating part. PTFE-based coatings can have a very low coefficient of friction but can be quite soft and can be rubbed off by abrasion or even a plastic nut with bronze nuts wearing through it quickly.