Telescopic springs – also known as spiral springs or spring guards – have been developed to protect against accidents and mechanical damage wherever there are rotating parts, such as spindles or shafts. They are designed to follow the motion of the machine by spring force. A telescopic spring guard cover is intended to cover a spindle or ball screw on a machine tool. Presently, more than 600 different standard sizes are available.
Protection for: Typically covering a spindle, lead screw, or ball screw on a machine tool
For applications with small, dry particles, Dynatect will recommend another type of protective cover for your application (such as a bellows, telescoping cover, or roll-up shade)
Material: High-quality blue spring steel strip (55-58 Rockwell) with rounded edges. Strength up to 1800 N/m². Thickness of 0.6 mm. Where coolants with a high water content are regularly used, we recommend telescopic springs made of stainless steel (material No.1.4.310). These, however, have less spring force and can therefore not be made in all sizes.
Speed: Standard telescopic springs are designed for speeds up to 40 m/min (26.25 in/sec). For higher speeds, Dynatect can provide other options like bellows, way covers, and shade rollers.
How do Telescopic Springs work?
Telescopic springs follow the motion of the machine by spring force and are held into position by pressure (they naturally want to expand) within a mounting collar and pilot/centering flange
Mounting Position/ Orientation
Telescopic springs are wound differently for different mounting positions (horizontal or vertical), their extension (Lmax horizontal or Lmax vertical) depending on size. Please select the desired spring from our catalog and be sure to specify the mounting position on your inquiry, so that we will make the right type of spring.
Horizontal & diagonal mounting positions: Telescopic springs designed for horizontal use have greater overlap of coils than springs for vertical use to avoid “sagging”. *Horizontal mounting position: Telescopic springs designed for horizontal use have greater overlap of coils than springs for vertical use to avoid “sagging”. The larger diameter should be where most chips occur.
Vertical mounting position: These springs have greater extended length than horizontal springs. The larger diameter (D2) should be at the top/higher mounting position. This avoids dirt from falling into the coils and has a self-cleaning effect.
General Information on the Design of Collars and Pilots for Telescopic Springs
If you wish to use a pilot and a collar, you should make allowance for the space needed. In other words, the inside diameter of the spring (D1) should in this case be chosen slightly larger, to make sure that the spring will fit over the pilot. See PDF for more information.
Centering should be provided at the ends of the springs to allow these to turn. The springs must be able to move freely and must not be fixed. The mounting sleeve and centering flange are not normally supplied with the springs. These flanges can be supplied as optional accessories.
Spring guards are easy to mount. A collar on one side and a pilot on the other are entirely sufficient. The springs must be able to move freely in them. They must not be fixed. If you wish to use a pilot and a collar, you should make allowance for the space needed. In other words, the inside diameter of the spring (D1) should in this case be chosen slightly larger, to make sure that the spring will fit over the pilot.
Telescopic springs are supplied tied down with wire. Caution: Springs are highly tensioned! Risk of injury! Be sure to follow the instructions, which are also supplied with the springs.
Dimensional Check: The spring will reach normal operating values after about 20 motion cycles. Only then is exact measurement of the inside diameter D1 (only at maximum extension) and the outside diameter D2 possible.
Sizing & Specs
How to Determine Size and Select a Part Number
Step 1 Download a copy of the Part List/Specs: Download Spring Specs (PDF) All dimensions are in millimeters. Also refer to the diagrams below.
Step 2 Determine the maximum diameter (d) of the part (lead screw, ball screw, shaft, spline cylinder) you are covering. Round up to the next largest diameter on the table under the column Ød. The spring cover cannot be smaller than the shaft diameter. For instance a (d) of 84mm, find the closest on the chart, Ød = 86 (mm)
Step 3: Determine the total space available to mount a spring (L max) and pick from the L max vert. if it is a vertically mounted cover, or the L max horiz. if it is horizontally or diagonally mounted. For example: 740 mm.
You may find more than one optimally sized options, but check the L min and remaining dimensions. The yellow highlight indicates that either blue spring steel or stainless steel is required. Stainless steel cannot be made in all sizes since the spring force is less.
If stainless steel is required, the next size up could be used but it is longer. This could result in a larger diameter of the spring ØD2 (mounting clearance), so be sure that this fits in your mounting area.
Our itemized list gives all the technical data of our Telescopic Springs. These are combined to form our order numbers:
Maintenance & Safety
The springs are maintenance-free. Depending on the degree of soiling, we recommend daily or weekly cleaning, followed by the application of a thin film of oil. Special oil spray can be supplied by us. Telescopic Springs should NEVER be greased!