Our precision screw drives provide you with the performance you expect with the options you need. Available in trapezoidal lead screws from 10mm-80mm diameter. Available in precision rolled ball screws from 8mm-125mm diameter and leads to 50mm. Our SPIRACON roller screw sets provide superior force, speed, and life characteristics for the most demanding applications.
Several parameters are used to describe screw drives. All our model numbers include the diameter of the screw and the lead. Other common parameters of screw drives are accuracy and backlash. The lead is the distance of travel in one revolution of the screw. Typically each diameter and lead will have a different load rating. There are two different types of load ratings. One load rating is the static load rating. This is an upper limit for the screw that should not be exceeded. The other load rating is the dynamic load rating. For rolling friction drives (see below) this represents the L10 or B10 life. If you apply this load to a group of the same screw drives after 1 million revolutions 10% of the screws would have failed. The formula to calculate life is a cubic relationship so if you halve your load your life goes up by 8 times.
There are three basic types of screw drives. The simplest is the lead screw drive. These are commonly know as ACME screws. The metric version of ACME screws are called trapezoidal screws. This name comes from the shape of the cross section of the screw. The lead screw typically uses a machined bronze nut. This nut contacts the screw on the flank of the thread and distributes the load over a large area. Another type of screw drive is the ball screw. Ball screws are very popular due to their high speed capability. The last style of screw drive is the planetary roller screw. The roller screw offers force capability rivaling the lead screw with speeds of the ball screw drive.

Lead Screws
Lead screws are capable of lifting large loads and handling moderate to high amounts of shock loading. The main drawback of lead screws is its sliding friction contact. Since lead screws rely on a sliding action their efficiency is rather low. Our trapezoidal lead screws range in efficiency from about 20% to 75%. This lower efficiency generates heat during operation and therefore limits the duty cycle of lead screw drives. This duty cycle limitation varies across applications, but is typically less than 30%. Due to the sliding friction of the lead screw drive more clearance is required in the nut. This results in a relatively high backlash between the nut and the screw.  All our lead screw drives are precision rolled.  Their accuracy ranges from T7 (± 0.002" per ft) to T10 (± 0.012" per ft). The biggest benefit of the lead screw drive is the low price.

Ball Screws
Ball screw drives utilize a large number of ball bearings as the interface between the screw and the nut. This rolling action with a low specific load on each ball gives a very high affiance. We typically figure on an affiance of 90% for our ball screw drives. This very low friction is well suited for preloaded drives that offer no backlash. Our ball screws are available in very high leads in one case 2.5 times larger than the diameter (our 20 mm diameter, 50 mm lead screw). With a screw speed of 3000 rpm these ball screws can move loads at up to 100 in/sec (2.5 m/s). This makes them perfect for light to medium load motion and servo drive applications.
The balls used inside a ball screw drive have to be returned back to the front of the nut after they have passed the length of the nut. This is accomplished by the nut's return system. Unlike many competitors we use only internal return systems. This offers a quieter and more reliable package that is easier to mount. This also allows us to run at higher rotational speeds due to optimization of the path the balls take between load zones. For our high lead screws we use up to 5 starts (independent threads) on the screw. Our ball nuts use all these starts for balls which gives us some of the shortest ball nuts available for high lead applications. Our rolled ball screws are offered in T7 tolerance class. We do offer in some sizes P5 (± 0.001" per ft). Our ground ball screws are available in P3 and P5.

Planetary Roller Screws
Planetary roller screws offer the high force of the lead screw with the high speed, high efficiency, and low backlash of a ball screw drive. Where the ball screw has a point rolling contact like a ball bearing the roller screw uses a line contact similar to a roller bearing. Due to the design of the roller screw very high tolerances are required in the nut. Therefore all contacting components of the roller screw drive are ground. This give a screw accuracy of (± 0.0003" per ft). This extremely high accuracy makes the planetary roller screw also suitable for replacement of ground ball screws where extra life or load capability is required. Our largest standard roller screw is rated dynamically to move 270,000 lbs.

Product Links
TGT Lead Screw / Nut Assemblies
KGT Rolled Ball Screw / Nut Assemblies
KGT-G Ground Ball Screw / Nut Assemblies
KOKON Ball Screw Drive with full protection
SPIRACON Planetary Roller Screw / Nut Assemblies