Five Awesome Lead Screw Designs

Christopher Nook by Christopher Nook

One of the great aspects of using a lead screw to automate an axis of your machine is that the design options are endless. Engineers can do virtually anything with the nut design as long as it incorporates the mating thread of the screw.

One of the great aspects of using a lead screw to automate an axis of your machine is that the design options are endless. Engineers can do virtually anything with the nut design as long as it incorporates the mating thread of the screw.

Here are just a few of the options that engineers have when they design a lead nut:

  • Materials: PEEK®, polyester, PVDF, Vespel®, Ertalyte®, Torlon®, bronze, aluminum, steel, stainless steel and brass
  • Manufacturing method: machined or molded
  • Insert Molding: add metal components to the nut in the molding process
  • Precision: freewheeling or anti-backlash
  • Temperature ranges: -40° F to 550° F

Lead screws also offer a wide array of design options:

  • Materials: stainless steel, alloy steel, aluminum, brass, bronze, plastic
  • Manufacturing Method: rolled, ground, milled, machined
  • Alternate Machining Options: friction welding (dissimilar materials can be combined to reduce overall costs)
  • Precision: +/- 0.0003”/ inch
  • Lubricants: PTFE, TFE
  • Protective Coatings: Black Oxide, Melanite (salt bath ferritic nitrocarburizing) Duracoat®, Cerakote™, nickel, chrome, Armalloy®
  • Temperature ranges: -40° F to 550° F

Below are five examples of really outstanding designs...

 

Example OneExample-1-aluminum-with-black-anodizing

  • Nut material: aluminum - 6061
  • Hollow screw: reduced overall assembly weight by approximately 50%
  • Screw material: 4140
  • Screw diameter: 0.500"
  • Screw lead: 0.500"
  • Starts: Five
  • Length: 5.00”

What makes it awesome? It was rolled out of a hollow piece of material which makes it a low cost solution for reducing weight.

Example TwoExample-2-custom-acetal-blend

  • Nut material: custom acetal blend
  • Twin lead screw: left and right hand thread
  • Screw material: 303 stainless
  • Screw diameter: 0.250”
  • Screw lead: 0.078”
  • Starts: Two
  • Length: 3.00”

What makes it awesome? It’s a miniature twin screw assembly that delivers opposite directions of movement simultaneously.

Example ThreeExample-3-Bronze-ret2

  • Nut material: Bronze
  • Screw material: 303 stainless
  • Screw diameter: 0.125”
  • Screw lead: 0.096”
  • Starts: Four
  • Length: 1.62”

What makes it awesome? The miniature trunion mounted nut, the precision machining on the end of the screw and the high lead.

Example Four Example-4-acetal

  • Nut material: Acetal
  • Screw material: 303 stainless
  • Screw diameter: 0.125”
  • Screw lead: 0.096”
  • Starts: Four
  • Length: 3.5”

What makes it awesome? The nut design incorporates several other components into the nut itself and reduces the overall BOM.

Example FiveExample-5-Polyamide-Nylon

  • Nut Material: Polyamide Nylon/Kevlar with Aramid and Molybdenum Disulphide fill (say that three times fast)
  • Screw material: aluminum
  • Coating: PTFE dry lubricant
  • Screw diameter: 11mm
  • Screw lead: 4mm
  • Starts: One
  • Length: 308mm

What makes it awesome? This nut is as tough as it gets when it comes to resisting high impact loads. The screw is rolled out of 6061 aluminum and the drive end of the screw eliminates the need for a coupling. It’s also coated in a PTFE dry lubricant.

Lead screws offer engineers excellent options for custom linear motion solutions. These screws are as precise as +/- 0.0003" / inch positioning accuracy and are also a very simple solution for converting rotary motion to linear motion with the added benefit of extremely smooth and quiet operation when compared to ball screws. Lead screws are also a great solution for "clean" applications where particulation and outgassing are not acceptable. The next time you consider using a screw as a means of linear motion for your machine, remember the many design options that you have at your disposal.