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Design Advantages of Linear UniSlide Assemblies

Compact design yields long travel in a short work space A simple, reliable design easily adaptable Modular components facilitate multiple axis system A broad variety of lengths, sizes and feature Customizing to accommodate special circumstances or uses View examples

Load Capacity
The size of the slide selected for a given application will depend on user requirements. The chart below provides maximum dynamic load capacities for each model for three different load positions.

*A25 Series with W1 or P10 leadscrews: LT = 30 lbs./13.5 kg. Static loads are twice the dynamic load values given above.

Orientation: Up, Down, Left and Right
The reference position for linear UniSlide Assemblies is with the base down, the slider up, and the knob, if any, facing the user.


Sketch 1

Construction
UniSlides begin as an extrusion of aluminum alloy with a straightness tolerance of half the normal commercial tolerance. Subsequent machining and lapping operations produce a very high degree of straightness and parallelism in the dovetail ways.
B-Type Base For increased base stiffness, several of our A-series bases - A25, A40 and A60 - are also available in the deeper B-series style . This extra stiffness is particularly useful when the full length of the base cannot be adequately supported. Typical stiffness of the B-series base is two to four times greater than the A-series.

Deviations from Straightness
There are three types of deviations from straightness than can occur: X, Y and Z. Picture a UniSlide resting base down on a flat surface, with its linear motion in the X or longitudinal direction. A departure from straightness in the upward direction-the Z axis-is designated as the bow error. A deviation in the horizontal direction-the Y axis-is horizontal run out, often referred to simply as run out. And a twist in the direction of the slide-the X axis-is called twist. The upper limits for these deviations from straightness, as determined by our manufacturing processes, are:

• Bow* 0.002" per foot
• Run Out 0.001" per foot
• Twist 1 milliradian per foot
  

* As installed, bow can be affected by the degree of flatness of the supporting surface and the relative tension of the mounting screws. Top
Straightness Tolerances
If your application requires improved straightness tolerances, we can supply UniSlides with straightness tolerances approximately one-half of the nominal values given previously. We individually select, measure and certify UniSlide Assemblies.

Operating Temperature
Maximum temperature for regular linear UniSlides is 250ºF or 121ºC. Higher temps can be achieved by substituting brass or Vespel (a durable high-performance polyimide) for the standard DelrinAF drive nut. Some Series A25 and all Series A15 have Delrin thrust bearings as well that have to be replaced. The maximum continuous operating temperature for the low friction bearing pads is 550˚F (300˚C).

For cold temperatures, brass drive nuts work best. They are also recommended for frequent cycling between extreme temperature such as in environmental test chambers.

Wear Resistance
The standard aluminum alloy dovetail base and low friction polymer pads of the slider provide excellent performance as a bearing material combination. Unlike ball screw slide mechanisms, no lubrication is required. Under light to moderate loads, sideways play caused by wear during the first 30,000 cycles of operation will be approximately 0.00015 inches. Wear after that is reduced, to approximately 0.00005 inches over the next 50,000 cycles. Sliders are equipped with adjustment screws to compensate for wear, if necessary. For harsh environments and/or a higher number of cycles, UniSlide Assemblies with hard coat anodized ways are available. For clean room environments we recommend electroless nickel plating.

Magnetic Properties

Photo 2: UniSlide with brass lead screw

We can make linear positioners with very low or no ferric (iron) content. UniSlide base and slider assemblies are made from aluminum alloy. Most lead screws are 303 stainless steel. The exceptions are the W1, W2 and P10, P5 lead screws which are cold rolled steel with electroless nickel plating. We can also substitute brass lead screws for some models. Brass lead screws (shown above) are only offered in standard grade accuracy. Thrust bearing using polymer raceways and cages with either glass or 316 SS balls are available. In a few models with small steel parts, a no nonmagnetic replacement is available. For further information please contact the factory. Top

Base and Slider Lengths
Standard and maximum base lengths for all models are listed in the specifications for each model. Custom base lengths are available on special order. Slider lengths available are only those listed in the model specifications.

Vacuum Applications
More on vacuum applications.

Back driving the lead screw
UniSlides with W2 or P5 lead screws can back drive under certain conditions.
See Lead Screws for additional details.

Scale and Control Lever Position
The control lever for Rapid Advance units is on the right hand side. Printed and engraved scales are on the left side as shown in the drawings and photos in this catalog. Scale numbering always progresses toward the knob end of the unit-i.e., the largest numbers on the scale are closest to the knob. Control levers, top plates, thumbscrew locks and verniers can be mounted on the alternate side on special request. If requested, the scale can be mounted on the right side of the UniSlide, with zero at the knob end of the base. For models with the base mounting holes located off the center line, holes begin at the bearing block end with the first hole to the right of the lead screw. See Dimensional Drawing for Series of choice, Top of page.

Material Substitutions
Material substitutions for drive nuts, lead screws and thrust bearing are possible. Drive nuts are available in brass, oil-impregnated bronze, and, for high temperature or radiation applications, in Vespel. Bearings can be manufactured from Delrin. Brass lead screws are available in a limited pitch selection.

Photo 3:Brass Drive Nut are often used in high and low temp environments

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