PRECISION MINIATURE LEAD SCREW ASSEMBLIES 3rd Edition

Helix Linear Technologies, Inc., Beachwood, Ohio Helix Linear Technologies, a subsidiary of Nook Industries, is the most hightech lead screw manufacturing facility in the world. With the release of our new precision lead screws, Helix produces the broadest product line of any lead screw manufacturer globally. We offer precision rolled, milled, or ground screws in diameters from 1 ⁄ 8 ”= to 6", or 3mm to 150mm, and leads from 0.024" to 3", or 3mm to 75mm. Helix offers a complete line of nuts in standard and anti-backlash designs with centralizing threads to match our precision lead screws. Our...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES HIGH TECH QUALITY EXPERIENCE When you select Helix Linear Technologies as a supplier, you can be assured that your product will be designed and tested to rigorous product planning. Pre-design activity includes understanding of customer requirements applied to predictive models, engineering calculations and linear modeling through prototype development, stereo-lithography samples of form, fit, and function that verify design criteria. VALIDATION AND VERIFICATION Through years of rigorous development, Helix has proven its designs and manufacturing processes...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES MATERIALS AND MANUFACTURING Helix Linear Technologies manufactures precision lead screws by thread rolling, thread milling, or thread grinding. Helix lead screw products feature centralizing and custom thread forms for smooth, no-wedging performance. THREAD ROLLING Helix offers the largest selection of rolled lead screw sizes in the industry. Rolled thread screws are precise, cost effective, and are stocked for quick delivery. THREAD MILLING Milled screws allow more variety in journal machining, particularly where a design requires the journal O.D. to...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES GLOSSARY AND TECHNICAL DATA THREAD TYPES The acme thread form, established over 100 years ago, replaced square thread screws, which had straight-sided flanks and were difficult to manufacture. LAND (MAJOR) DIAMETER - The outside diameter of the screw. There are three main classes of acme thread forms: general purpose (G), centralizing (C), and stub acme. The General Purpose and Centralizing thread forms have a nominal depth of thread of 0.50 × pitch and have a 29° included thread angle. Trapezoidal thread forms have a 30° included thread angle. Helix...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES GLOSSARY AND TECHNICAL DATA (continued)END MACHINING / MOUNTING DEFINITIONS Nut A The three basic types of end fixity are: See page 12 for a more detailed definition of end fixity. BACKLASH - Backlash (lash) is the relative axial clearance between a screw and nut without rotation of the screw or nut. Backlash information for Helix precision lead screws and nuts is listed within the data section of this catalog. Lash will always increase with use. Helix Linear Technologies has developed several unique ways to reduce or remove the lash between the screw...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES MOUNTING AND PINNING OF FLANGES TORQUE DESIGN CONSIDERATIONS The preferred method of locking a flange to a nut is a pin or set screw parallel to the screw which intersects the flange/nut mounting thread. Because of the dissimilarity of materials, the hole may need to be milled, not drilled. Alternatively, the flange may be drilled and tapped radially for a set screw. After assembly of the flange to the nut, spot drill the nut threads through the flange and install a dog point set screw from the flange O.D. into the nut O.D. threads. Avoid getting metal...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES Multiple or Spaced Pairs of bearings are more rigid than a "Simple" support, but because of their compliance are not truly "Fixed". LEAD SCREW SELECTION The selection of the correct lead screw and nut for a particular application involves four interrelated factors. Before attempting to determine the lead screw and nut combination, the following values must be known: • Axial load measured in pounds or newtons • Speed measured in inches or millimeters per minute • Length between bearings measured in inches or millimeters • End fixity type LOAD - The loads...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES CRITICAL SPEED CHART - INCH SCREWS CRITICAL SPEED CHART - METRIC SCREWS Every screw shaft has a rotational speed limit. That is the point at which the rotational speed sets up excessive vibration. This critical point can be modified by the type of end bearing support used. Every screw shaft has a rotational speed limit. That is the point at which the rotational speed sets up excessive vibration. This critical point can be modified by the type of end bearing support used. To use this chart, determine the required RPM and the maximum length between bearing...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES COLUMN LOADING CAPACITIES CHART - INCH SCREWS COLUMN LOADING CAPACITIES CHART - METRIC SCREWS The chart below will help you determine the Maximum Compression Load for Screw Shaft. Usually, screws operated in tension can handle loads up to the rated capacity of the nut, providing the screw length is within standard lengths. End supports have an effect on the load capacity of screws. The four standard variations are shown below with corresponding rating adjustments. Find the point of intersecting lines of load (horizontal) and length (vertical) to determine...

PRECISION MINIATURE LEAD SCREW ASSEMBLIES Proper lubrication is the key to continued performance and reliability of lead screw assemblies. Use E-100 spray and PAG-1 grease lubricants to maximize life of your acme screw assembly. BENEFITS • Sheer Stability • High Temperature Resistant • Corrosion Protection • Separation Resistant • Extreme Pressure Properties • Shelf Stable • Water Resistant MINIATURE LEAD SCREW ASSEMBLIES REFERENCE NUMBER SYSTEM Product Grade Penetration Dropping Gelling CST CST Temp. Contents Total Name Number (Worked) Point Agent @40°C @100°C Range Per Unit Part No. Weight...